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Fill in the blanks and win 2 gold coins.

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A great article describing how abiotic and biotic things interact in our ecosystem!

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Together, abiotic and biotic factors make up an ecosystem. Abiotic factors are the non-living parts of an environment. These include things such as sunlight, temperature, wind, water, soil and naturally occurring events such as storms, fires and volcanic eruptions. Biotic factors are the living parts of an environment, such as plants, animals and micro-organisms. Together, they are the biological factors that determine a species' success. Each of these factors impacts others, and a mix of both is necessary for an ecosystem to survive.

TL;DR (Too Long; Didn't Read)

Abiotic and biotic factors together make up an ecosystem. Abiotic or non-living factors are those such as climate and geography. Biotic factors are living organisms.

Abiotic factors can be climatic, related to weather, or edaphic, related to soil. Climatic factors include air temperature, wind and rain. Edaphic factors include geography such as topography and mineral content, as well as soil temperature, texture, moisture level, pH level and aeration.

Climatic factors greatly impact which plants and animals can live within an ecosystem. Prevailing weather patterns and conditions dictate the conditions under which species will be expected to live. The patterns not only help to create the environment but also impact water currents. Changes in any of these factors, such as those that occur during occasional fluctuations such as El Niño, have a direct impact and can have both positive and negative effects.

Changes in air temperature affect the germination and growing patterns of plants as well as the migration and hibernation patterns in animals. While seasonal changes occur in many temperate climates, unexpected changes can have negative results. Although some species can adapt, sudden changes can result in inadequate protection from severe conditions (for example, being without a winter coat of fur) or without sufficient food stores to last through a season. In some habitats, such as in coral reefs, species may be unable to migrate to a more hospitable location. In all these cases, if they are unable to adapt, they will die off.

Edaphic factors impact plant species more than animals, and the effect is greater on larger organisms than it is on smaller ones. For example, variables such as elevation impact plant diversity more than that of bacteria. This is seen in forest tree populations where elevation, the slope of the land, exposure to sunlight and the soil all play a role in determining the population of particular tree species in a forest. Biotic factors also come into play. The presence of other tree species has an impact. The regeneration density of trees tends to be higher in locations where there are other trees of the same species nearby. In some cases, the presence of certain other species of trees nearby is associated with lower regeneration levels.

Land masses and elevation influence wind and temperature. For example, a mountain can create a wind break, which impacts the temperature on the other side. Ecosystems at higher elevations experience lower temperatures than those at lower elevations. In extreme cases, elevation can cause arctic or sub-arctic conditions even in tropical latitudes. These differences in temperature can make it impossible for a species to journey from one suitable environment to another if the path between requires traveling through changing elevations with inhospitable conditions.

Minerals such as calcium and nitrogen levels affect the availability of food sources. The level of gases such as oxygen and carbon dioxide in the air dictate which organisms can live there. Differences in terrain such as soil texture, composition and the size of sand grains also can impact a species' ability to survive. For example, burrowing animals require certain types of terrain to create their homes, and some organisms require rich soil while others do better in sandy or rocky terrain.

In many ecosystems, abiotic factors are seasonal. In temperate climates, normal variations in temperature, precipitation and the amount of daily sunlight affect the ability of organisms to grow. This has an impact not only on plant life but also on the species that rely on the plants as a food source. Animal species may follow a pattern of activity and hibernation or may adapt to changing conditions through coat, diet and body-fat changes. Changing conditions encourage high diversity rates among species in an ecosystem. This can help stabilize populations.

The environmental stability of an ecosystem impacts the population of species that call it home. Unexpected changes may indirectly change the food web as changing conditions make it more or less hospitable and influence whether a particular species will establish itself. While many abiotic factors occur in a rather predictable manner, some occur infrequently or without warning. These include natural events such as droughts, storms, flooding, fires and volcanic eruptions. These events can have a great impact on the environment. As long as they do not occur with great frequency or over too large an area, there are benefits to these natural events. When spaced optimally, these events can be highly beneficial and rejuvenate the environment.

Extended droughts negatively impact an ecosystem. In many areas, plants cannot adapt to changing rain patterns, and they die. This also affect organisms further up the food chain that are forced to migrate to another area or make diet changes in order to survive.

Storms provide necessary precipitation, but heavy rain, sleet, hail, snow and high winds can damage or destroy trees and plants, with mixed environmental results. While damage to organisms can occur, this thinning of branches or forests can help strengthen existing species and provide room for new species to grow. On the other hand, heavy rains (or rapid snow melt) can cause localized erosion, weakening the support system.

Floods can be beneficial. Floodwaters provide nourishment to plants that may otherwise not get enough water. Sediment that may have settled in riverbeds is redistributed and replenishes the nutrients in the soil, making it more fertile. The newly deposited soil also can help prevent erosion. Of course floods also cause damage. High floodwaters can kill animals and plants, and aquatic life may be displaced and die when the waters recede without them.

Fire also has both harmful and beneficial effects on an ecosystem. Plant and animal life may be injured or die. The loss of live root structures can result in erosion and later sedimentation of waterways. Harmful gases may be produced and may be carried by winds, affecting other ecosystems as well. Potentially damaging particulates that end up in waterways can be consumed by aquatic life, negatively impacting the water quality. However, fire also can be rejuvenating to a forest. It fosters new growth by cracking open seed coats and triggering germination or by prompting tree pods in the canopy to open and release seeds. Fire clears the undergrowth, reducing competition for seedlings and providing a fresh bed for seeds that is rich in nutrients.

Volcanic eruptions initially result in destruction, but the rich nutrients in volcanic soil later benefit plant life. On the other hand, an increase in water acidity and temperature can be harmful to aquatic life. Birds may experience lost habitat, and their migration patterns may be disrupted. An eruption also forces multiple gases into the atmosphere that can impact oxygen levels and affect respiratory systems.

All living organisms, from microscopic organisms to humans, are biotic factors. Microscopic organisms are the most plentiful of these and are widely distributed. They are highly adaptable, and their reproduction rates are rapid, allowing them to create a large population in a short time. Their size works to their advantage; they can be dispersed over a large area quickly, either through abiotic factors such as wind or water currents, or by traveling in or on other organisms. The simplicity of the organisms also aids in their adaptability. The conditions needed for growth are few, so they can easily thrive in a greater variety of environments.

Biotic factors impact both their environment and each other. The presence or absence of other organisms influences whether a species needs to compete for food, shelter and other resources. Different species of plants may compete for light, water and nutrients. Some microbes and viruses can cause diseases that may be transmitted to other species, thus lowering the population. Beneficial insects are the primary pollinators of crops, but others have the potential to destroy crops. Insects also may carry diseases, some of which can be transmitted to other species.

The presence of predators impacts the ecosystem. The effect this has depends on three factors: the number of predators in a given environment, how they interact with prey and how they interact with other predators. The existence of multiple predator species in an ecosystem may or may not impact each other, depending on their preferred food source, the size of the habitat and the frequency and quantity of food required. The greatest impact is made when two or more species consume the same prey.

Things such as wind or water currents can relocate micro-organisms and small plants and allow them to start new colonies. This spread of species can be beneficial to the ecosystem as a whole as it can mean a larger food supply for primary consumers. However, it can be a problem when established species are forced to compete with new ones for resources and those invasive species take over and disrupt the balance of the ecosystem.

In some cases, biotic factors can prevent abiotic factors from doing their job. An overpopulation of a species can impact abiotic factors and have a negative effect on other species. Even the smallest organism, such as phytoplankton, can devastate an ecosystem if it is allowed to overpopulate. This is seen in "brown algal blooms" where an excessive number of algae collect on the surface of the water and prevent the sunlight from reaching the area below, effectively killing all life beneath the water. On land, a similar situation is seen when a tree canopy grows to cover a large area, effectively blocking the sun from reaching plant life below.

The Arctic and Antarctic not only have extreme cold temperatures, but these temperatures also vary by season. In the Arctic Circle, the Earth's rotation allows minimal sun to reach the surface, resulting in a short growing season. For example, the growing season in the Arctic National Wildlife Refuge is only 50 to 60 days with a temperature range of 2 to 12 degrees Celsius. With the Arctic Circle oriented away from the sun, the winters have short days, with temperatures ranging from -34 to -51 degrees Celsius (-29 to -60F). High winds (up to 160 km/hour, or about 100 miles per hour) pelt exposed plants and animals with ice crystals. While the snow cover provides insulating benefits, the extreme conditions do not allow any new plant growth.

Biotic factors are few in the Arctic. Conditions only allow for low-lying plants with shallow root structures. Most of these have dark green to red leaves that absorb more sunlight and reproduce asexually, through budding or cloning, rather than sexually via seeds. Most plant life grows just above the permafrost, as the soil is several inches below. Because of the very short summer, plants and animals reproduce quickly. Many animals are migratory; those that live in the Arctic National Wildlife Refuge tend to have smaller appendages and larger bodies than their southern counterparts that enable them to stay warm. Most mammals also have both an insulating layer of fat and a protective coat that resists cold and snow.

At the other temperature extreme, arid deserts also pose challenges for biotic factors. Living organisms need water to survive, and the abiotic factors in a desert (temperature, sunlight, topography and soil composition) are inhospitable to all but a few species. The temperature range of most major American deserts is from 20 to 49 degrees Celsius (68 to 120F). Precipitation levels are low, and rainfall is inconsistent. The soil tends to be coarse and rocky with little to no subsurface water. There is little to no canopy, and plant life tends to be short and sparse. Animal life also tends to be smaller, and many species spend their days in a burrow, emerging only during the cooler nights. While this environment is favorable for succulents such as cacti, poikilohydric plants survive by maintaining a dormant state between rains. After a rain, they become photosynthetically active and reproduce rapidly before again assuming the dormant state.

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The Definition of Abiotic and Biotic Factors

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Both abiotic and biotic factors are necessary to an ecosystem. Abiotic factors are the non-living elements such as weather and geological processes; biotic factors are the living organisms such as plants and birds. Together, they are the biological factors that determine a species' success.

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This is the article given to you during the Do Now in class

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Extra video to help with your learning

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Definition of an Energy Pyramid

When we talk about the food chain or food web, we typically conjure to mind a lion chasing a gazelle, or perhaps a grazing cow. We imagine one organism being eaten by another and typically associate a large, carnivorous predator at the 'top' of the food chain. While this does show the ecological relationships between organisms, it doesn't exactly show the flow of energy through the ecosystem.

This is where an energy pyramid (sometimes called a trophic pyramid or ecological pyramid) is useful in quantifying the energy transfer from one organism to another along the food chain. Energy decreases as you move through the trophic levels from the bottom to the top of the pyramid.

Energy Transfers

So, we have outlined that an energy pyramid diagrams a transfer of energy through the food chain, but what exactly is this 'energy' we are describing and where does it come from? The whole reason why organisms must eat is to obtain this metabolic energy, vital for their ability to function.

1. The energy starts with the sun!

2. Plants produce metabolic energy via photosynthesis, wherein approximately 10% of their energy is stored in their tissues, available for consumption by a grazing herbivore. The rest of the solar energy was used by the plant in its own metabolism, lost as heat or lost as waste.

3. Of that 10% that an herbivore eats, only 10% of that is stored in its tissues to be eaten by a carnivore. Just like the plant, the other 90% of its metabolic energy is used up by the herbivore in functioning, excreting waste, and heat loss.

4. This continues up the pyramid with each subsequent carnivore only inheriting 10% of the previous level's energy.

5. By the time that the original solar energy hits the top of the pyramid, as little as 0.1% of the energy is consumed by the top predator; the rest is lost to metabolic activities.

6. Decomposers, such as bacteria, worms, and fungi, obtain the little amount of energy remaining in the tissues of dead plants and animals.

The 10% rule states that about 90% of energy from food is used for bodily processes or lost as heat, leaving 10% of the original energy available to feed the next consumer.

Think of this process like a group of people standing in a line. The person at the front of the line is holding a handful of rice. He then tosses the handful of rice to the next person, who tosses it to the next person, and so on. The person at the end of the line would be lucky to catch a couple of grains of rice, as the rest of it would be dropped in the process of playing catch! The rice is analogous to the energy being passed through the pyramid: A little bit is retained, but most is lost to the process.

For this reason, consumers on each step up the energy pyramid must consume a very high quantity of their food source to get enough energy from it. This diagram shows the energy equivalencies of organisms on different levels of the energy pyramid: 10,000 freshwater shrimp could feed 1,000 bleak, which could feed 100 perch, which in turn could feed 10 northern pike, which finally could feed just 1 osprey.

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what is an energy pyramid? - definition & examples - video & lesson transcript | study.com

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What is an Energy Pyramid? - Definition & Examples - Video & Lesson Transcript | Study.com

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When we talk about the food chain or food web, we typically conjure to mind a lion chasing a gazelle, or perhaps a grazing cow. We imagine one organism being eaten by another and typically associate a large, carnivorous predator at the 'top' of the food chain.

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A big thanks to all current and future patrons who are helping fund this science communication outreach via Patreon: http://bit.ly/2Sfmkph Symbiosis is close...

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An electronic copy of the Symbiosis article

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Play the "Primary and Secondary Succession" game. Fill out your graphic organizer as you play the game.

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Succession Interactive!

Topics Covered: Ecological succession, Primary succession, Secondary succession, abiotic and biotic factors, pioneer species, critical thinking, graph analysis, NGSS (Next Generation Science Standards), pheonomena. For NGSS, see LS2.C: Ecosystem Dynamics, Functioning, and Resilience specifically.

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Video computer games, virtual labs and activities for learning and reviewing biology content. Great for students and teachers.

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Communities are dynamic and change over time, and we can observe this process with particular clarity after a disturbance or on new land. Learn about primary and secondary succession, as well as pioneer species.

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Ecological Succession Reading and Questions

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When you talk about the causes of climate change, most people immediately think of dirty smoke pouring out from smokestacks, burning trash heaps, or forests on fire. It's true the smoke and soot that you can see with your naked eye is harmful and often incredibly toxic. But it's the stuff you can't see that in the long run is the deadliest. I call them the four deadly gases - carbon dioxide, methane, nitrogen oxides, and F-gases - which are driving global climate change through the .

Each gas has a different warming effect. Carbon dioxide (CO2) is by far the most prevalent greenhouse gas - about 38 tonnes were emitted in our reference year of 2010, mostly from energy production and deforestation. There is a lot less methane (CH4) being emitted into the atmosphere but it has a much greater warming impact (about 25 times more potent than CO2). In 2010 we emitted about 9 tonnes of methane CO2e (carbon dioxide equivalent), most of it from agricultural production. The same year we emitted about 3 tonnes of nitrogen oxides (NOx) again mostly from agriculture, and another 1 tonne in F-gases, from industrial production and coolants.

The simple chart below combines these four gases and shows how much TOTAL CO2e was created in 2010 from various human activities. When you boil it all down it is actually pretty simple. About 2/3 of the total pollution causing climate change comes from the burning of fossil fuels - coal, oil, and natural gas. Another 1/4 of emissions come from land use changes and agriculture, including livestock. The last 9% or so comes from 3 other important but relatively smaller sources - F-gases like HCFC's used in your refrigerator (2.2%), emissions from making cement (3.3%) and emissions from waste (3.4%).

Coal is the worst of the worst, accounting for about 28% of total global warming. Next up is oil accounting for 23%, and natural gas, accounting for another 19% of total global warming. These figures include about 1.5 billion tonnes of "fugitive emissions" - or gases that escape during the storage or transport of the fuel supplies. When you combine that with another 4.5% of additional pollution from the mining, drilling and processing of fossil fuels you realize just what an inefficient energy system we have.

There is quite a lot of confusion around land-use changes, agriculture, and livestock. There was even a film recently that suggested that we don't really need to fix our energy system if we all just stop eating meat. That is definitely not the case. But as the scientist Gidon Eshel explains in Before the Flood, emissions from producing meat are indeed enormous, as are other land uses. See Livestock: Global Indigestion "

Let's start with land clearing and deforestation. Nearly 13% of all pollution causing global warming is from cutting down (and often burning) trees and other wildlands mostly in South America, Africa, and Asia. What is driving it? It differs greatly by continent, but altogether clearing land for food crops is the biggest reason, and most of that is from large-scale industrial farming operations. Palm oil plantations are the worst in this category, as was depicted in the film. Literally 80% of Indonesia's rainforest has been torched to make room for these plantations, making the country one of the world's worst polluters.

You'll also notice another 3% is for land clearing for livestock feed. If you add that together with emissions from manure, which is mostly used to fertilize feed crops, and emissions from enteric fermentation (aka cows burping) you can attribute more than 10% of global warming to livestock.

If you want to geek on the different causes of global warming by gas type and also by end use, dive into the sankey chart below produced by scientists at the University of Cambridge and Published in the Journal of Environmental Science & Technology, 2013.

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When you talk about the causes of climate change, most people immediately think of dirty smoke pouring out from smokestacks, burning trash heaps, or forests on fire. It's true the smoke and soot that you can see with your naked eye is harmful and often incredibly toxic.

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Major sources of evidence for Climate Change

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Major sources of evidence for Climate Change

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Climate Change: Vital Signs of the Planet

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The rate of change since the mid-20th century is unprecedented over millennia.

Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years ago marking the beginning of the modern climate era - and of human civilization. Most of these climate changes are attributed to very small variations in Earth's orbit that change the amount of solar energy our planet receives.

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.) Find out more about ice cores (external site).

The current warming trend is different because it is clearly the result of human activities since the mid-1800s, and is proceeding at a rate not seen over many recent millennia. It is undeniable that human activities have produced the atmospheric gases that have trapped more of the Sun's energy in the Earth system. This extra energy has warmed the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred.

Do scientists agree on climate change?

Yes, the vast majority of actively publishing climate scientists - 97 percent - agree that humans are causing global warming and climate change.

detailed answer

Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate.

Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century. Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response.

"Scientific evidence for warming of the climate system is unequivocal."

- Intergovernmental Panel on Climate Change

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth's climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age.

References

References
Header image shows clouds imitating mountains as the sun sets after midnight as seen from Denali's backcountry Unit 13 on June 14, 2019. Credit: NPS/Emily Mesner

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Climate Change Evidence: How Do We Know?

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Vital Signs of the Planet: Global Climate Change and Global Warming. How do we know it's happening? Here's the evidence.

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Decomposing plants and other organisms, buried beneath layers of sediment and rock, have taken millennia to become the carbon-rich deposits we now call fossil fuels. These non-renewable fuels, which include coal, oil, and natural gas, supply about 80 percent of the world's energy. They provide electricity, heat, and transportation, while also feeding the processes that make a huge range of products, from steel to plastics.

When fossil fuels are burned, they release carbon dioxide and other greenhouse gases, which in turn trap heat in our atmosphere, making them the primary contributors to global warming and climate change.

Major types of fossil fuels

There are several main groups of fossil fuels, including:

Coal: Black or brown chunks of sedimentary rock that range from crumbly to relatively hard, coal began to form during the Carboniferous period about 300 to 360 million years ago, when algae and debris from vegetation in swamp forests settled deeper and deeper under layers of mud. Mined via surface or underground methods, coal supplies a third of all energy worldwide, with the top coal consumers and producers in 2018 being China, India, and the United States. Coal is classified into four categories-anthracite, bituminous, sub-bituminous, and lignite-depending on its carbon content.

Carbon dioxide emissions from burning coal account for 44 percent of the world total, and it's the biggest single source of the global temperature increase above pre-industrial levels. The health and environmental consequences of coal use, along with competition from cheap natural gas, have contributed to its decline in the U.S. and elsewhere. But in other places, such as India, demand is expected to rise through 2023.

Oil: Crude oil, a liquid composed mainly of carbon and hydrogen, is often black, but exists in a variety of colors and viscosities depending on its chemical composition. Much of it formed during the Mesozoic period, between 252 and 66 million years ago, as plankton, algae, and other matter sank to the bottom of ancient seas and was eventually buried.

Extracted from onshore and offshore wells, crude oil is refined into a variety of petroleum products, including gasoline, diesel, and heating oil. The top oil-producing countries are the U.S., Saudi Arabia, and Russia, which together account for nearly 40 percent of the world's supply.

Petroleum use accounts for nearly half the carbon emissions in the U.S. and about a third of the global total. In addition to the air pollution released when oil is burned, drilling and transport have led to several major accidents, such as the Exxon Valdez spill in 1989, the Deepwater Horizon disaster in 2010, the devastating Lac Megantic oil train derailment in 2013, and thousands of pipeline incidents. Nonetheless, oil demand continues to rise, driven not only by our thirst for mobility, but for the many products- including plastics -made using petrochemicals, which are generally derived from oil and gas.

Natural gas: An odorless gas composed primarily of methane, natural gas often lies in deposits that, like those for coal and oil, formed millions of years ago from decaying plant matter and organisms. Both natural gas and oil production have surged in the U.S. over the past two decades because of advances in the drilling technique most people know as fracking.

By combining fracking-or hydraulic fracturing-with horizontal drilling and other innovations, the fossil-fuel industry has managed to extract resources that were previously too costly to reach. As a result, natural gas has surpassed coal to become the top fuel for U.S. electricity production, and the U.S. leads the world in natural gas production, followed by Russia and Iran.

Natural gas is cleaner than coal and oil in terms of emissions, but nonetheless accounts for a fifth of the world's total, not counting the so-called fugitive emissions that escape from the industry, which can be significant. Not all of the world's natural gas sources are being actively mined. Undersea methane hydrates, for example, where gas is trapped in frozen water, are being eyed as a potential gas resource.

Reducing emissions from fossil fuels

Governments around the world are now engaged in efforts to ramp down greenhouse gas emissions from fossil fuels to prevent the worst effects of climate change. At the international level, countries have committed to emissions reduction targets as part of the 2015 Paris Agreement, while other entities-including cities, states, and businesses-have made their own commitments. These efforts generally focus on replacing fossil fuels with renewable energy sources, increasing energy efficiency, and electrifying sectors such as transportation and buildings.

However, many sources of carbon emissions, such as existing power plants that run on natural gas and coal, are already locked in. Considering the world's continuing dependence on fossil fuels, many argue that in addition to efforts aimed at replacing them, we also need to suck carbon from the air with technologies such as carbon capture, in which emissions are diverted to underground storage or recycled before they reach the atmosphere. A handful of commercial-scale projects around the world already capture carbon dioxide from the smokestacks of fossil fuel-fired plants, and while its high costs have prevented wider adoption, advocates hope advances in the technology will eventually make it more affordable.

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Decomposing plants and other organisms, buried beneath layers of sediment and rock, have taken millennia to become the carbon-rich deposits we now call fossil fuels. These non-renewable fuels, which include coal, oil, and natural gas, supply about 80 percent of the world's energy.

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Alternative Title: mineral fuel

Fossil fuel, any of a class of hydrocarbon-containing materials of biological origin occurring within Earth's crust that can be used as a source of energy.

sedimentary rock: Organic-rich sedimentary deposits

Coal, oil shale, and petroleum are not sedimentary rocks per se; they represent accumulations of undecayed organic tissue that can either...

Fossil fuels include coal, petroleum, natural gas, oil shales, bitumens, tar sands, and heavy oils. All contain carbon and were formed as a result of geologic processes acting on the remains of organic matter produced by photosynthesis, a process that began in the Archean Eon (4.0 billion to 2.5 billion years ago). Most carbonaceous material occurring before the Devonian Period (419.2 million to 358.9 million years ago) was derived from algae and bacteria, whereas most carbonaceous material occurring during and after that interval was derived from plants.

All fossil fuels can be burned in air or with oxygen derived from air to provide heat. This heat may be employed directly, as in the case of home furnaces, or used to produce steam to drive generators that can supply electricity. In still other cases-for example, gas turbines used in jet aircraft-the heat yielded by burning a fossil fuel serves to increase both the pressure and the temperature of the combustion products to furnish motive power.

Since the beginning of the Industrial Revolution in Great Britain in the second half of the 18th century, fossil fuels have been consumed at an ever-increasing rate. Today they supply more than 80 percent of all the energy consumed by the industrially developed countries of the world. Although new deposits continue to be discovered, the reserves of the principal fossil fuels remaining on Earth are limited. The amounts of fossil fuels that can be recovered economically are difficult to estimate, largely because of changing rates of consumption and future value as well as technological developments. Advances in technology-such as hydraulic fracturing ( fracking), rotary drilling, and directional drilling-have made it possible to extract smaller and difficult-to-obtain deposits of fossil fuels at a reasonable cost, thereby increasing the amount of recoverable material. In addition, as recoverable supplies of conventional (light-to-medium) oil became depleted, some petroleum-producing companies shifted to extracting heavy oil, as well as liquid petroleum pulled from tar sands and oil shales. See also coal mining; petroleum production.

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One of the main by-products of fossil fuel combustion is carbon dioxide (CO ₂). The ever-increasing use of fossil fuels in industry, transportation, and construction has added large amounts of CO ₂ to Earth's atmosphere. Atmospheric CO ₂ concentrations fluctuated between 275 and 290 parts per million by volume (ppmv) of dry air between 1000 ce and the late 18th century but increased to 316 ppmv by 1959 and rose to 412 ppmv in 2018. CO ₂ behaves as a greenhouse gas-that is, it absorbs infrared radiation (net heat energy) emitted from Earth's surface and reradiates it back to the surface. Thus, the substantial CO ₂ increase in the atmosphere is a major contributing factor to human-induced global warming. Methane (CH ₄), another potent greenhouse gas, is the chief constituent of natural gas, and CH ₄ concentrations in Earth's atmosphere rose from 722 parts per billion (ppb) before 1750 to 1,859 ppb by 2018. To counter worries over rising greenhouse gas concentrations and to diversify their energy mix, many countries have sought to reduce their dependence on fossil fuels by developing sources of renewable energy (such as wind, solar, hydroelectric, tidal, geothermal, and biofuels) while at the same time increasing the mechanical efficiency of engines and other technologies that rely on fossil fuels.

Otto C. Kopp The Editors of Encyclopaedia Britannica

Learn More in these related Britannica articles:

sedimentary rock: Organic-rich sedimentary deposits

Coal, oil shale, and petroleum are not sedimentary rocks per se; they represent accumulations of undecayed organic tissue that can either make up the bulk of the material (e.g., coal), or be disseminated in the pores within mudrocks, sandstones, and carbonates (e.g., oil...

thermoelectric power generator: Fossil-fuel generators

Generators have been constructed to use natural gas, propane, butane, kerosene, jet fuels, and wood, to name but a few heat sources. Commercial units are usually in the 10- to 100-watt output power range. These are for use in remote areas in applications...

climate: The biosphere and Earth's energy budget

...material has been transformed into fossil fuels (coal, petroleum, natural gas, and others) by geologic processes acting upon the remains of plants and animals over many millions of years. Different forms of carbon may be burned and thus used as energy sources. In so doing, organic carbon is converted into...

did you know?

In 2015, coal fueled approximately one-third of the United States's electricity.

There are approximately 1.7 trillion barrels of crude oil reserves worldwide.

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Fossil fuel, hydrocarbon-containing material of biological origin that can be burned for energy. Fossil fuels, which include coal, petroleum, and natural gas, supply the majority of all energy consumed in industrially developed countries. Learn about the types of fossil fuels, their formation, and uses.

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An aerial shows the contrast between forest and agricultural landscapes near Rio Branco, Acre, Brazil. Photo by CIFOR/CC BY-NC 2.0
Lauren Bennett | April 18, 2017

Forests play many important ecological roles. From helping to mitigate climate change; providing homes for many species of plants and animals (some endemic to forested regions); providing food, medicine and livelihoods for people around the globe; to the intrinsic values of forests, these essential ecological powerhouses are irreplaceable-and at risk. Forests cover 31% of our planet;the Amazon rainforest alone is home to hundreds of thousands of species of plants and animals.Yet, despite everything forests do for the planet, they are being cut down at an alarming rate. Every year 46-58 thousand square miles of forest are lost to deforestation, which is equal to an astounding 48 football fields of forest disappearing every minute. Although there is much cause for concern when considering the degradation of forests worldwide, many still have hope that with the right changes in policy and perception, forests can still be saved.

What is Causing Deforestation?
Agriculture
There are many factors that contribute to deforestation, each with its own causes and negative environmental impacts.

Agriculture is one of the most significant causes of deforestation.

The first form of agriculture that will be examined is slash-and-burn agriculture. Slash-and burn agriculture can be a sound agricultural practice in many instances, and has long been practiced by many aboriginal communities. Although the jury is still out on how sustainable this practice is, many believe that small scale practice of slash and burn, or "swidden," as practiced by some aboriginal communities, can actually be beneficial to the soil and biodiversity.

Slash-and-burn agriculture is responsible for the loss of around 50 acres of land every hour worldwide. One of the issues with slash and burn is that fires intentionally set can unintentionally spread throughout the forest.When fire spreads to unintended areas, the protective forest canopy is destroyed. The resulting sun exposure to the forest floor intensifies the existing fire.The smoke then "hangs over the forest, and suppresses rainfall," making it even more difficult to extinguish as the area becomes drier.

For example, in the Amazon rainforest the seasons are so extreme, in terms of precipitation, that there are just two named seasons: "wet" and "dry." During the dry season, the problems with slash-and-burn agriculture are intensified. Although there are many, complex issues surrounding the use of slash-and-burn agriculture in the Amazon, the underlying rationale for the practice is very simple: the soil in the Amazon rainforest is infertile,much to the dismay of the estimated 250 million farmers working the poor soil of the tropical forests there. For impoverished farmers, the simplest solution to this problem is to cut down the trees, and burn what remains. This makes the soil more fertile as incinerated biomass provides nitrogen and other nourishing nutrients for the soil.

Unfortunately, this is a short term solution. The soil only stays nutrient rich for so long, about two years, after this time, the nutrients from the burned biomass are used up. When this happens, farmers pack up and move on to the next section of the rainforest, leaving their farmland behind for others to use for cattle rearing, or abandonment.
Raising Cattle
Furthermore, slash-and-burn agriculture on this scale can also have devastating affects for the biodiversity in the area. With large areas of land being incinerated, many animal habitats are lost in the fire. This pushes animals out of the forest, decreasing biodiversity, and increasing the number of endangered and extinct animal species.

Cattle ranching has a massive impact on forests around the world, particularly tropical rainforests like the Amazon. Many farmers use deforested areas of land to raise cattle; however, it might surprise you to learn that corporations do this on a much larger scale. Fast food companies have been contributing to deforestation in places like the Amazon rainforest for quite some time, and only in relatively recent years have their actions been acknowledged by mainstream media. Companies that have been deforesting the rainforest in order to raise cattle for their hamburgers include: Wal-mart, McDonalds, Pizza Hut, and Burger King, just to name a few. Although some of these companies have made promises to be more environmentally conscious, some, such as Burger King and Pizza Hut, have made no plans to move away from this harmful and unnecessary form of animal agriculture.

Logging is also a common cause of deforestation as trees are cut down to use for paper products. There are several different types of logging: however, the most harmful one is called "clear cutting." This is when an area of forest is completely deforested, leaving no trees alive in that area.

In some cases, areas of forest that have been clear cut are candidates for remediation. Remediation of clear cut areas of forest, however, comes with its own issues. Often times mono-planting is a go-to remediation plan, which is to say that only one species of tree is planted in that area. Although this does help to remediate the complete loss of trees, it doesn't remediate much else. All of the biodiversity lost to clear cutting is not remedied by mono-planting. This is because biodiversity is supported by a diversity of flora as well as fauna. By simply planting 1,000 oak trees in an area which previously was home to many species of trees, the environment now only supports those animals that find food or shelter from oak trees alone. Mono-cropping is therefore not a sustainable solution to clear cut land.

Housing, also called "urban sprawl" is the final major contributing cause of deforestation. Urban sprawl is one of the most difficult deforestation-related issues to solve. This is due to the fact that, at its base, urban sprawl is driven by overpopulation. In fact, overpopulation is one the most complex and pressing issues at the base of many environmental problems. It is difficult to find a solution to overpopulation because of its nature-however a shorter-term solution, like changes in infrastructure, can be made to mitigate the issue. Environmentalists and architects alike have come up with numerous designs for cities over the years centred on housing the largest amount of people with the smallest environmental impact.

One interesting examples of such an infrastructure change is an architectural concept called "compact cities," or what some people are calling "tiny cities" or "sustainable cities." There are many different concepts for a compact city, depending on the available land as well as current and projected population density and growth: however, the idea is always the same. A compact city occupies a smaller area of land than a traditional city, and still houses a large amount of people, while remaining small enough to make vehicles obsolete, making your home, work, entertainment, green space and everyday businesses such as grocery stores and doctor's offices within walking distance. These designs are usually achieved by designing exceptionally tall buildings in a small area, which would be broken up into sections; living, grocery, doctors- all in one skyscraper.

Climate Change

Although in some instances it can be advantageous, burning biomass on such a large scale comes with many consequences. It is estimated that the total amount of biomass burned by humans make up a whopping 90% of the total number, where natural fires are only around 10%. According to NASA,

"Since fires produce carbon dioxide, a major greenhouse gas, biomass burning emissions significantly influence the Earth's atmosphere and climate. Biomass burning has both short- and long-term impacts on the environment. Vegetation acts as a sink-a natural storage area-for carbon dioxide by storing it over time through the process of photosynthesis. As burning occurs, it can release hundreds of years worth of stored carbon dioxide into the atmosphere in a matter of hours. Burning also will permanently destroy an important sink for carbon dioxide if the vegetation is not replaced."

In addition to its local effects, burning organic materials on a large scale, like what is done with slash-and-burn agriculture, emits greenhouse gases, which contribute to global climate change.

It is estimated that 25% of the world's total greenhouse gas production comes from deforestation alone. Furthermore, forests around the world store more than double the amount of carbon cioxide than is found in the atmosphere. This means that when areas are deforested, the carbon dioxide stored in those trees is released into the atmosphere.

Logging for paper products is one of the simplest causes of deforestation to solve. By recycling and not relying so much on paper products, the amount of land deforested for this purpose can be reduced.

Urban Sprawl

As urban sprawl moves into forested areas, it greatly contributes to climate change while also threatening the natural environment and biodiversity. According to one study, "projected urban expansion could consume hundreds of thousands of hectares' worth of key biodiversity hotspots over the next twenty years, triggering the release of some 5 billion tons of carbon dioxide from direct land use change and further endangering hundreds of species."The amount of carbon that could be released by urban sprawl is staggering. Furthermore, expanding out into forested areas, especially rainforests, decrease biodiversity. The decrease in biodiversity coupled with increasing rates of climate change will not only shift the way the land is used and the ecology of the land itself, but also increased the potential for the success of invasive species, which will only further change the environment around cities. "City populations are expected to grow by five billion people and expand by 1.2 million square kilometers by 2030. Much of this expansion is forecasted to occur in the tropics, which contain the bulk of the world's species. The new study attempts to quantify the impact of urbanization on the world's so-called 'hotspots' - nearly three dozen areas with exceptionally high levels of species found nowhere else" which means "that by 2030, nearly three percent of hotspot areas will be urbanized, up from one percent in 2000. While the extent seems small, paving over marshes, forests, and grasslands could generate 1.38 billion tons of carbon emissions (5 billion tons of CO2) from direct land use change."

The figure above outlines the impacts that urban sprawl will have on specific regions with biodiverse hot spots.

Other impacts
Water Cycles
Deforestation affects climate change on a large scale, as discussed in the sections above; however, climate change is not the only negative consequence of deforestation. There are many other ways in which deforestation has negative impacts to the environment.

Trees undergo a natural process called "transpiration." This is when the leaves of trees secrete water which is evaporated into the atmosphere. When this water evaporates, it becomes clouds, which, as part of the hydrological cycle, swells with moisture and rains back down again. When trees are cut down in a forest, it eliminates or decreases the amount of transpiration, which means that the amount of rainfall in that area will decrease. This can lead to droughts in the area. When the trees in area are cut down for agricultural purpose, it actually affects the success of local crops. With less naturally occurring water, farmers have to make a more intensive effort to ensure that their crops are properly hydrated, which can cost the farmers even more money.
Loss of Biodiversity
As show in the image above, trees and plants are an integral part of the hydrological cycle, and the loss of plant and tree life can greatly influence local weather patterns.
Soil Erosion
The loss of forests also means the loss of habitats for many species of plants and animals. "Seventy percent of the world's plants and animals live in forests and are losing their habitats to deforestation. Naturally, the loss of habitat means the loss of species and therefore the loss of biodiversity. Loss of biodiversity has varied negative impacts regarding the environment. Once a habitat is lost on a large scale, it can be very difficult for local species to recover, especially endemic species, which are more common in areas such as tropical rainforests, which are so dense with endemic species they are referred to as "hot-spots."

When trees are cut down, it means that the surrounding soil becomes loosened from the ground, and can be blown away by wind, or washed away by rain. This becomes an issue for farmers who deforested the land to plant crops. This problem can become very serious, as "The WWF states that scientists estimate that a third of the world's arable land has been lost to deforestation since 1960. After a clear cutting, cash crops like coffee, soy and palm oil are planted. Planting these types of trees can cause further soil erosion because their roots cannot hold onto the soil."The loss of trees is the primary cause of soil erosion due to deforestation, and land-use practices in many cases exacerbates the soil erosion issue. Soil erosion can cause many issues not only for the environment, but also the health and wellbeing of people who live in the area. "'The situation in Haiti compared to the Dominican Republic is a great example of the important role forests play in the water cycle,' Daley said. Both countries share the same island, but Haiti has much less forest cover than the Dominican Republic. As a result, Haiti has endured more extreme soil erosion, flooding and landslide issues."

Where does deforestation happen?

Deforestation happens all over the world. However, the vast majority of deforestation takes place in rainforest around the globe, mostly concentrated mainly in the tropics.

The above figure shows the countries with the greatest amount of deforestation. Brazil has the most amount of land deforested between 1990 and 2005-in just 15 years, 40,000 hectares of forest was cut down in Brazil.

Although Brazil has the most amount of forest loss measured in hectares, other countries have lost a much greater amount of forest as a percentage of their total forest cover. For example, although Comoros does not have the most hectares loss, it does have the largest percentage loss. In 15 years Comoros lost an astounding 50% of their forested land.

The Amazon rain forest is one of the most threatened forests on earth. The Amazon spans 670 million hectares across several countries, "Brazil, Bolivia, Peru, Colombia, Ecuador, Venezuela, Guyana, Suriname, and French Guiana,"of which 17.7 million hectares has already been lost due to deforestation.

As you can see in the figure above, although there are some protection policies in place, they aren't always effective. 19% of the Amazon rainforest in eight counties is protected land; however, more than half of that percentage, 9%, of protected areas are still experiencing deforestation. Furthermore, half of the indigenous occupied areas in eight countries of the amazon rainforest are also experiencing deforestation (2% of the 4% occupied by indigenous people.)

What will the future look like?

If we continue on this path, as much as 55% of the amazon rainforest could disappear by the year 2030. The damage to the Amazon alone is so great, in fact, that fires set for slash-and-burn agriculture, as well as the scars left on the Amazonian rainforest, can be seen from space. With the massive loss of trees in forests comes a massive loss in all the things that go hand in hand with this rich diverse environment. Animal species, plant species, medicine, livelihoods, weather patterns, and natural beauty will all be greatly affected following the loss of forested areas.

The two maps above show the damage to Borneo's rainforest between 1973 (left) and 1973-2010 (right.)

The impact of losing 55% of the Amazonian rainforest would be incalculable. Scientists say that the 55% of forest loss is projected to make up "31 percent cleared and 24 percent damaged by either logging or drought, with a large portion of that damaged forest catching fire."

Conclusion
Lauren Bennett is a Graduate Research Fellow at the Climate Institute
Forests and Rainforests world-wide are at risk. There are many changes that must be made locally, and globally, in order to secure the existence and success of these ecologically and environmentally significant areas of land. Although recent trends indicate that deforestation is on the rise, there are also many who are fighting back. Following plans for environmentally based initiatives, the forests of the world can still be saved. The next generation, environmentally conscious and ready to make a change, may be the final key to unlocking the preservation and protection of forests.

PDF version with references available here.

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An aerial shows the contrast between forest and agricultural landscapes near Rio Branco, Acre, Brazil. Photo by CIFOR/ CC BY-NC 2.0 Forests play many important ecological roles. From helping to mitigate climate change; providing homes for many species of plants and animals (some endemic to forested regions); providing food, medicine and livelihoods for people around the globe; to the intrinsic values of forests, these essential ecological powerhouses are irreplaceable-and at risk.

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Agricultural expansion, illegal logging, mining and urbanization continue to drive deforestation around the world. Globally, forests are under threat — large-scale efforts are needed to protect these ecosystems and the many benefits they provide.

One Belgium, every year

According to satellite data 1, 2, from 2002 through 2019, global tropical forest loss averaged 3.36 million hectares (8.3 million acres) a year — an area larger than Belgium. Tweet this fact »

Half gone

More than half the world’s tropical forests have been destroyed since the 1960s.3 Tweet this fact »

Every six seconds

In 2019, the world lost an entire soccer field worth of primary rainforest every six seconds.4 Tweet this fact »

Brazil under siege

Between 2001 and 2019, Brazil lost 565,000 square kilometers (218,148 square miles) of tree cover — an area larger than the state of California — to deforestation.5 Tweet this fact »

60 percent

Ghana saw a 60 percent spike in the loss of its primary forests between 2017 and 2018 — more than any other tropical country.6 Tweet this fact »

Stand up for forests, they need you

Forests are vital to the health of the planet — providing our air, food and water. As trees disappear, deforestation will cost us all. Your donation will help us support communities around the world as they protect forests.

40% due to agriculture

Commercial agriculture — such as cattle ranching, soy cultivation and oil palm plantations — drives 40 percent of deforestation worldwide.7 Mining, infrastructure and urbanization are also key culprits. Tweet this fact »

45 million jobs

Globally, the formal forest sector provides 45 million jobs and about US$ 580 billion in labor income.7 Estimates are likely much higher if the informal forest sector is included. Tweet this fact »

1.6 billion people

Deforestation impacts 1.6 billion rural people worldwide who rely on forests for their livelihoods3 — most live in extreme poverty. Tweet this fact »

12% of emissions

Forests release carbon dioxide when they are cleared or burnt. About 12 percent of global greenhouse gas emissions come from deforestation8 — roughly equivalent to emissions from all the cars and trucks on Earth. Tweet this fact »

Increasing pressure

By 2050, the global demand for food could double. Using existing farmland more efficiently could feed more people without clearing additional forests and wetlands.9 Tweet this fact »

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References

1. Global Forest Watch. Global Primary Forest Loss. Retrieved March, 2020, from https://www.globalforestwatch.org/dashboards/global

2. Weisse, M. and Goldman, E.D. (2020, June 2). We Lost a Football Pitch of Primary Rainforest Every 6 Seconds in 2019. World Resources Institute. https://www.wri.org/blog/2020/06/global-tree-cover-loss-data-2019

3. International Union for Conservation of Nature. (2021, February). Deforestation and forest degradation. https://www.iucn.org/resources/issues-briefs/deforestation-and-forest-degradation

4. Global Forest Watch. (2020, June). We Lost a Football Pitch of Primary Rainforest Every 6 Seconds in 2019. https://blog.globalforestwatch.org/data-and-research/global-tree-cover-loss-data-2019/

5. Global Forest Watch. Global Tree Cover Loss. Retrieved March, 2020, from https://www.globalforestwatch.org/dashboards/global

6. Weisse, M. and Goldman, E.D. (2019, April 25). The World Lost a Belgium-sized Area of Primary Rainforests Last Year. World Resources Institute. https://www.wri.org/blog/2019/04/world-lost-belgium-sized-area-primary-rainforests-last-year

7. FAO and UNEP. 2020. The State of the World’s Forests 2020. Forests, biodiversity and people. Rome. https://doi.org/10.4060/ca8642en

8. Brack, Duncan. (2019). Background Analytical Study: Forests and Climate Change. United Nations Forum on Forests. https://www.un.org/esa/forests/wp-content/uploads/2019/03/UNFF14-BkgdStudy-SDG13-March2019.pdf

9. Tilman, D., Balzer, C., Hill, J., & Befort, B. L. (2011). Global food demand and the sustainable intensification of agriculture. Proceedings of the National Academy of Sciences, 108(50), 20260–20264. https://doi.org/10.1073/pnas.1116437108

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Deforestation: 11 facts you need to know

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Agricultural expansion, illegal logging, mining and urbanization continue to drive deforestation around the world. Globally, forests are under threat — large-scale efforts are needed to protect these ecosystems and the many benefits they provide.

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Every time a cow burps or passes gas, a little puff of methane wafts into the atmosphere.

Each of those puffs coming out of a cow's plumbing, added together, can have a big effect on climate because methane is a potent greenhouse gas-about 28 times more powerful than carbon dioxide at warming the Earth, on a 100-year timescale, and more than 80 times more powerful over 20 years. The effects aren't just hypothetical: Since the Industrial Revolution, methane concentrations in the atmosphere have more than doubled, and about 20 percent of the warming the planet has experienced can be attributed to the gas.

There's not that much methane in the atmosphere-about 1,800 parts per billion, about as much as two cups of water inside a swimming pool. That's about 200 times less concentrated in the atmosphere than carbon dioxide, the most abundant and dangerous of the greenhouse gases. But methane's chemical shape is remarkably effective at trapping heat, which means that adding just a little more methane to the atmosphere can have big impacts on how much, and how quickly, the planet warms.

Methane is a simple gas, a single carbon atom with four arms of hydrogen atoms. Its time in the atmosphere is relatively fleeting compared to other greenhouse gases like CO ₂-any given methane molecule, once it's spewed into the atmosphere, lasts about a decade before it's cycled out. That's a blip compared to the centuries that a CO ₂ molecule can last floating above the surface of the planet. But there are many sources of methane, so the atmospheric load is constantly being regenerated-or increased.

Today, about 60 percent of the methane in the atmosphere comes from sources scientists think of as human caused, while the rest comes from sources that existed before humans started influencing the carbon cycle in dramatic ways.

Most of methane's natural emissions come from a soggy source: wetlands, which includes bogs. Many microbes are like mammals in that they eat organic material and spit out carbon dioxide-but many that live in still, oxygen-deprived spots like waterlogged wetland soils produce methane instead, which then leaks into the atmosphere. Over all, about a third of all the methane floating in the modern atmosphere comes from wetlands.

There are a variety of other natural methane sources. It seeps out of the ground naturally near some oil and gas deposits and from the mouths of some volcanoes. It leaks out of thawing permafrost in the Arctic and builds up in the sediments under shallow, still seas; it wafts away from burning landscapes, entering the atmosphere as CO ₂; and it is produced by termites as they chow through piles of woody detritus. But all of these other natural sources, excluding wetlands, only make up about ten percent of the total emissions each year.

Human sources of methane

Today, human-influenced sources make up the bulk of the methane in the atmosphere.

Cows and other grazing animals get a lot of attention for their methane-producing belches and releases. Such grazers host microbes in their stomachs, gut-filling hitchhikers that help them break down and absorb the nutrients from tough grasses. Those microbes produce methane as their waste, which wafts out of both ends of cows. The manure that cattle and other grazers produce is also a site for microbes to do their business, producing even more methane. There are 1.4 billion cattle in the world, and that number is growing as demand for beef and dairy increases; together with other grazing animals, they contribute about 40 percent of the annual methane budget.

Other agricultural endeavors pump methane into the atmosphere, too. Rice paddies are a lot like wetlands: When they're flooded, they're filled with calm waters low in oxygen, which are a natural home for methane-producing bacteria. And some scientists think they can see the moment when rice production took off in Asia, about 5,000 years ago, because methane concentrations-recorded in tiny bubbles of ancient air trapped in ice cores in Antarctica-rose rapidly.

Methane also leaks into the atmosphere at gas and oil drilling sites. There are strict rules in place in many states and countries about how much leakage is allowed, but those rules have proven difficult to enforce. Recent studies suggest that wells in the U.S. alone are producing about 60 percent more methane than previously estimated by the Environmental Protection Agency. Worldwide, the energy sector contributes about a quarter of the annual methane budget.

Another major source? Waste. Microbes in landfills and sewage treatment centers chomp through the detritus humans leave behind and in the process pump out tons of methane each year-about 14 percent of the U.S.'s annual footprint.

Methane's impact on climate, past and future

Methane may also have been the cause of rapid warming events deep in Earth's history, millions of years ago. Under high pressure, like the pressures found deep at the bottom of the ocean, methane solidifies into a slush-like material called methane hydrate. Vast amounts of methane are "frozen" in place at the bottom of the sea in this chemical state, though the exact amounts and locations are still being studied. The hydrates are stable unless something comes along to disturb them, like a plume of warm water.

A massive warming event that occurred about 55 million years ago may have been kicked off by destabilized hydrates, some scientists think. Methane percolated up from the seafloor into the atmosphere, flooding it with the heat-trapping gas and forcing the planet to warm drastically and quickly.

In the modern atmosphere, methane concentrations have risen by more than 150 percent since 1750. It's not clear whether this rise will continue, or at what rate, but the IPCC warns that keeping methane emissions in check is necessary in order to keep the planet from warming further.

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Every time a cow burps or passes gas, a little puff of methane wafts into the atmosphere. Each of those puffs coming out of a cow's plumbing, added together, can have a big effect on climate because methane is a potent greenhouse gas-about 28 times more powerful than carbon dioxide at warming the Earth, on a 100-year timescale, and more than 80 times more powerful over 20 years.

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Concrete is the most widely used man-made material in existence. It is second only to water as the most-consumed resource on the planet.
But, while cement - the key ingredient in concrete - has shaped much of our built environment, it also has a massive carbon footprint.

Cement is the source of about 8% of the world's carbon dioxide (CO2) emissions, according to think tank Chatham House.

If the cement industry were a country, it would be the third largest emitter in the world - behind China and the US. It contributes more CO2 than aviation fuel (2.5%) and is not far behind the global agriculture business (12%).

Cement industry leaders were in Poland for the UN's climate change conference - COP24 - to discuss ways of meeting the requirements of the Paris Agreement on climate change. To do this, annual emissions from cement will need to fall by at least 16% by 2030.

So, how did our love of concrete end up endangering the planet? And what can we do about it?

In praise of concrete

As the key building material of most tower blocks, car parks, bridges and dams, concrete has, for the haters, enabled the construction of some of the world's worst architectural eyesores.

In the UK, it helped the massive wave of post-World War Two development - much of it still dividing opinion - with several of the country's major cities, such as Birmingham, Coventry, Hull and Portsmouth, largely defined by the concrete structures from that building push.

But concrete is also the reason some of the world's most impressive buildings exist.

Sydney Opera House, the Lotus Temple in Delhi, the Burj Khalifa in Dubai as well as the magnificent Pantheon in Rome - boasting the largest unsupported concrete dome in the world - all owe their form to the material.

A mix of sand and gravel, a cement binder and water, concrete is so widely embraced by architects, developers and builders because it is a remarkably good construction material.

"It's affordable, you can produce it almost anywhere and it has all the right structural qualities that you want to build with for a durable building or for infrastructure," explains Felix Preston, deputy research director at the Energy, Environment and Resources Department at Chatham House.

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The illusion of concrete Britain

Despite known durability problems with using steel reinforcement, which can crack concrete from the inside, it is still the go-to material across the world.

"Building without concrete, although it is possible, is challenging," says Mr Preston.

Growth of cement industry

It is these unrivalled attributes of concrete that have helped boost global cement production since the 1950s, with Asia and China accounting for the bulk of growth from the 1990s onwards.

Production has increased more than thirtyfold since 1950 and almost fourfold since 1990. China used more cement between 2011 and 2013 than the US did in the entire 20th Century.

But with Chinese consumption now appearing to level off, most future growth in construction is expected to happen in the emerging markets of South East Asia and sub-Saharan Africa - driven by rapid urbanisation and economic development.

The floor area of the world's buildings is projected to double in the next 40 years, say Chatham House researchers, requiring cement production to increase by a quarter by 2030.

Concrete has a long history

While many of us assume concrete is a recent addition to our cities, architects and builders have actually been using it for millennia.

The earliest use of concrete is believed to have been more than 8,000 years ago, with traders in Syria and Jordan creating concrete floors, buildings and underground cisterns.

Later, the Romans were known to be masters of concrete, building the Pantheon in Rome in 113-125AD, with its 43m-diameter free-standing concrete dome the largest in the world.

But the concrete used in our modern-built environment owes much of its make-up to a process patented in the early 19th Century by bricklayer Joseph Aspdin of Leeds.

His new technique of roasting limestone and clay in an oven and then grinding it to a powder to make "artificial stone" is now known as Portland cement - still the key ingredient in almost all modern concrete.

But, despite its ubiquitous presence, concrete's environmental credentials have come under increased scrutiny in the last couple of decades.

Not only does the production of Portland cement involve quarrying - causing airborne pollution in the form of dust - it also requires the use of massive kilns, which require large amounts of energy.

The actual chemical process of making cement also emits staggeringly high levels of CO2.

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'Action needed'

The sector has made progress - improvements in the energy-efficiency of new plants and burning waste materials instead of fossil fuels has seen the average CO2 emissions per tonne of output fall by 18% over the last few decades, according to Chatham House.

The newly-established Global Cement and Concrete Association (GCCA), currently representing about 35% of the world's cement production capacity and with a focus on sustainable development, was at COP24.

Chief executive Benjamin Sporton says the fact the organisation now exists "is a demonstration of the commitment of the industry to sustainability, including taking action on climate change".

The GCCA is due to publish a set of sustainability guidelines, which its membership will have to follow.

"By bringing together global players to provide leadership and focus, as well as delivering a detailed work programme, we can help ensure a sustainable future for cement and concrete, and for the needs of future generations," Mr Sporton says.

But despite the promise, Chatham House argues that the industry is reaching the limits of what it can do with current measures.

If the sector has any hope of meeting its commitments to the 2015 Paris Agreement on climate change, it will need to look at overhauling the cement-making process itself, not only reducing the use of fossil fuels.

'Clinker' - the big polluter

It is the process of making "clinker" - the key constituent of cement - that emits the largest amount of CO2 in cement-making.

1. Raw materials, mainly limestone and clay, are quarried and crushed

2. They are ground and mixed with other materials - such as iron ore or ash

3. They are fed into huge, cylindrical kilns and heated to about 1,450C (2,640F)

4. The process of "calcination" splits the material into calcium oxide and CO2

5. A new substance called clinker emerges as marble-sized grey balls

6. The clinker is cooled, ground and mixed with gypsum and limestone

7. The cement is transported to ready-mix concrete companies

In 2016, world cement production generated around 2.2 billion tonnes of CO2 - equivalent to 8% of the global total. More than half of that came from the calcination process.

Together with thermal combustion, 90% of the sector's emissions could be attributed to the production of clinker.

Because of this, Mr Preston and his colleagues argue the sector urgently needs to pursue a number of CO2 reduction strategies.

Further efforts on energy efficiency, a move away from fossil fuels and pursuing carbon capture and storage will help, but can only do so much.

"We've got a long way to close the gap," Mr Preston says.

What the industry really needs to do is plough efforts into producing new types of cement, he argues. In fact, low-carbon cements and "novel cements" might do away with the need for clinker altogether.

New cements

One of those trying to drum up greater support for such alternative cements is Ginger Krieg Dosier, co-founder and CEO of BioMason - a start-up in North Carolina that uses trillions of bacteria to grow bio-concrete bricks.

The technique, which involves placing sand in moulds and injecting it with microorganisms, initiates a process similar to the one that creates coral.

"I have a long fascination with marine cements and structures," explains Ms Krieg Dosier, a trained architect who was surprised to find no real green alternatives to bricks and masonry when she began research at an architectural firm more than 10 years ago.

The discovery led her to create her own solution, which, after years of development, now takes only four days. It happens at room temperature, without the need for fossil fuels or calcination - two of the main sources of the cement industry's CO2 emissions.

Ms Krieg Dosier believes green cements and technologies such as hers offer a solution to the sector's emissions issue.

"Traditional Portland-based cement production practices will continue to release CO2 due to its fundamental chemistry," she says, adding that rather than turning to carbon capture and storage, we should be investing more in techniques that actively remove carbon from the atmosphere.

"Alternative cements and binding technologies go beyond evolutionary CO2 capture to revolutionary methods that fundamentally sequester CO2."

'Disruptive forces'

Alongside such alternative cements, other "disruptive" forces are also beginning to drive change. Digitalisation, machine learning and an increasing awareness of sustainability are all having an impact on the cement industry's culture.

"It's partly changing because of how people want to live, but also because of our ability to dream up new and innovative structures and test those with computer models," says Mr Preston. "There's also the ability to build things more cheaply with robots - with automation."

But changing processes quickly enough to meet the cement industry's obligations will be a challenge.

The sector is dominated by a small number of major producers who are reluctant to experiment or change business models. Architects, engineers, contractors and clients are also, rather understandably, cautious about using new building materials.

"This quite slow-moving, difficult-to-change sector is starting to bump against these quite profound disruptions that we're starting to see in the built environment," says Mr Preston.

But, with very few low-carbon cements reaching commercialisation, and none being applied at scale in an industry where bigger and taller is often the ambition, it looks likely that sustained government support will be needed.

Without governments applying pressure on the industry or providing funding, it may not be possible to get the next generation of low-carbon cements out of the laboratory and into the market within the required timescale.

And the timescale is ever-shrinking.

The Intergovernmental Panel on Climate Change - the leading international body on global warming - last month argued the global average temperature rise needed to be kept below 1.5C - not 2C as noted in the Paris Agreement. This means CO2 emissions need to decline by 45% from 2010 levels by 2030.

Like other young companies, Ms Krieg Dosier describes the difficulties of simultaneously developing and marketing her products and scaling up manufacturing processes to compete within the wider construction industry.

But she thinks there are reasons to be optimistic.

"I do believe the construction industry is approaching a point where alternative materials will be more widely adopted," she says. "This is in part due to market demand, other innovative technologies and wider concern for climate change."

The cement industry, too, points to more optimistic assessments of the industry's progress on emissions and suggests that, across its lifetime, concrete could make a net climate benefit when all possible action is taken into account.

This includes re-carbonation (or the re-absorption of CO2 by cement), concrete's contribution to the energy efficiency of buildings, and innovation in the way cement is manufactured - including carbon capture and storage.

The GCCA says such innovation is its key priority in the months and years ahead. Projects are already underway and showing promise, it added.

But Mr Preston says it is imperative that governments and industry now act quickly at a time when global development is expected to rise but CO2 emissions need to fall.

"There's a desperate need for quality, affordable homes," he says. "There's a need for new infrastructure. We can only square this circle if we can dramatically improve the way that we build, so that overall these buildings are constructed with, as close as possible, net zero emissions."

Design by Lilly Huynh.

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The massive CO2 emitter you may not know about

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Concrete is the most widely used man-made material in existence. It is second only to water as the most-consumed resource on the planet. But, while cement - the key ingredient in concrete - has shaped much of our built environment, it also has a massive carbon footprint.

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best way to fight climate change? plant trees - cnn

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The most effective way to tackle climate change? Plant 1 trillion trees

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What's low-tech, sustainable and possibly the most effective thing we can do to fight climate change? Planting trees. A trillion of them.

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Biofuels have been around longer than cars have, but cheap gasoline and diesel have long kept them on the fringe. Spikes in oil prices, and now global efforts to stave off the worst effects of climate change, have lent new urgency to the search for clean, renewable fuels.

Our road travel, flights, and shipping account for nearly a quarter of the world's greenhouse gas emissions, and transportation today remains heavily dependent on fossil fuels. The idea behind biofuel is to replace traditional fuels with those made from plant material or other feedstocks that are renewable.

But the concept of using farmland to produce fuel instead of food comes with its own challenges, and solutions that rely on waste or other feedstocks haven't yet been able to compete on price and scale with conventional fuels. Global biofuel output needs to triple by 2030 in order to meet the International Energy Agency's targets for sustainable growth.

There are various ways of making biofuels, but they generally use chemical reactions, fermentation, and heat to break down the starches, sugars, and other molecules in plants. The resulting products are then refined to produce a fuel that cars or other vehicles can use.

Much of the gasoline in the United States contains one of the most common biofuels: ethanol. Made by fermenting the sugars from plants such as corn or sugarcane, ethanol contains oxygen that helps a car's engine burn fuel more efficiently, reducing air pollution. In the U.S., where most ethanol is derived from corn, fuel is typically 90 percent gasoline and 10 percent ethanol. In Brazil-the second-largest ethanol producer behind the U.S.-fuel contains up to 27 percent ethanol, with sugarcane as the main feedstock.

Alternatives to diesel fuel include biodiesel and renewable diesel. Biodiesel, derived from fats such as vegetable oil, animal fat, and recycled cooking grease, can be blended with petroleum-based diesel. Some buses, trucks, and military vehicles in the U.S. run on fuel blends with up to 20 percent biodiesel, but pure biodiesel can be compromised by cold weather and may cause problems in older vehicles. Renewable diesel, a chemically different product that can be derived from fats or plant-based waste, is considered a "drop-in" fuel that does not need to be blended with conventional diesel.

Other types of plant-based fuel have been created for aviation and shipping. More than 150,000 flights have used biofuel, but the amount of aviation biofuel produced in 2018 accounted for less than 0.1 percent of total consumption. In shipping, too, adoption of biofuel is at levels far below the 2030 targets set by the International Energy Agency.

Renewable natural gas, or biomethane, is another fuel that potentially could be used not only for transportation but also heat and electricity generation. Gas can be captured from landfills, livestock operations, wastewater, or other sources. This captured biogas then must be refined further to remove water, carbon dioxide, and other elements so that it meets the standard needed to fuel natural-gas-powered vehicles.

What is biofuel made from?

A variety of materials, or feedstocks, can be used to make biofuels. Though corn and sugarcane are well-established ethanol feedstocks, the process of growing the crops, making fertilizers and pesticides, and processing the plants into fuel consumes a lot of energy-so much energy that there is debate about whether ethanol from corn actually provides enough of an environmental benefit to be worth the investment.

So scientists and startups are exploring other materials that have the potential to serve as fuel without the accompanying concerns about food supply and environmental impact. Cellulosic ethanol, for example, uses corn stover, wood waste, or other plant material that would not be used otherwise. Other potential biofuel feedstocks include grasses, algae, animal waste, cooking grease, and wastewater sludge, but research continues to find the most efficient and cost-effective ways to transform them into usable fuel.

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Biofuels have been around longer than cars have, but cheap gasoline and diesel have long kept them on the fringe. Spikes in oil prices, and now global efforts to stave off the worst effects of climate change, have lent new urgency to the search for clean, renewable fuels.

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We Need Your Support
to Make Change Happen

We can protect consumers, the climate, and our environment from the growing costs and risks of our oil use -but not without you. Your generous support helps develop science-based solutions for a healthy, safe, and sustainable future.

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Cleaner Cars from Cradle to Grave (2015)

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We can protect consumers, the climate, and our environment from the growing costs and risks of our oil use -but not without you. Your generous support helps develop science-based solutions for a healthy, safe, and sustainable future.

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Solar energy is the technology used to harness the sun's energy and make it useable. As of 2011, the technology produced less than one tenth of one percent of global energy demand.

Many are familiar with so-called photovoltaic cells, or solar panels, found on things like spacecraft, rooftops, and handheld calculators. The cells are made of semiconductor materials like those found in computer chips. When sunlight hits the cells, it knocks electrons loose from their atoms. As the electrons flow through the cell, they generate electricity.

On a much larger scale, solar-thermal power plants employ various techniques to concentrate the sun's energy as a heat source. The heat is then used to boil water to drive a steam turbine that generates electricity in much the same fashion as coal and nuclear power plants, supplying electricity for thousands of people.

How to Harness Solar Power

In one technique, long troughs of U-shaped mirrors focus sunlight on a pipe of oil that runs through the middle. The hot oil then boils water for electricity generation. Another technique uses moveable mirrors to focus the sun's rays on a collector tower, where a receiver sits. Molten salt flowing through the receiver is heated to run a generator.

Other solar technologies are passive. For example, big windows placed on the sunny side of a building allow sunlight to heat-absorbent materials on the floor and walls. These surfaces then release the heat at night to keep the building warm. Similarly, absorbent plates on a roof can heat liquid in tubes that supply a house with hot water.

Solar energy is lauded as an inexhaustible fuel source that is pollution- and often noise-free. The technology is also versatile. For example, solar cells generate energy for far-out places like satellites in Earth orbit and cabins deep in the Rocky Mountains as easily as they can power downtown buildings and futuristic cars.

Pitfalls

Solar energy doesn't work at night without a storage device such as a battery, and cloudy weather can make the technology unreliable during the day. Solar technologies are also very expensive and require a lot of land area to collect the sun's energy at rates useful to lots of people.

Despite the drawbacks, solar energy use has surged at about 20 percent a year over the past 15 years, thanks to rapidly falling prices and gains in efficiency. Japan, Germany, and the United States are major markets for solar cells. With tax incentives, and efficient coordination with energy companies, solar electricity can often pay for itself in five to ten years.

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Solar Power Has Benefits as a Source of Alternative Energy

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Solar energy is the technology used to harness the sun's energy and make it useable. As of 2011, the technology produced less than one tenth of one percent of global energy demand. Many are familiar with so-called photovoltaic cells, or solar panels, found on things like spacecraft, rooftops, and handheld calculators.

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* Carbon capture and storage works, but is expensive to build or to retrofit onto old plants. * We'd need to do a lot more capturing and storing to make a difference in battling worldwide carbon emissions. * There are other dangers associated with burning coal, too.
For decades now, "clean coal" has been a political pipe dream. It's the idea that coal-our oldest, dirtiest energy source-could be reshaped in a way that lets us keep using it without doing so much harm to the environment. But what is it, exactly?

The term "clean coal" has been applied to many technologies, ranging from wet scrubbers, which remove sulfur dioxide from coal-generated gas, to coal washing, which removes soil and rock from coal before it's sent to a factory. Hypothetically, the term could be applied to anything that makes coal plants more efficient, like digitization. However, when people talk about clean coal these days, they're typically talking about something called carbon capture and storage (CCS).

CCS technology has been around since the 1980s. While the other technologies mentioned above cut down on sulfur dioxide and coal ash (which are important), CCS is meant to handle the big environmental nightmare, the heat-trapping gas largely responsible for global warming, carbon dioxide (CO2).

Coal plants today typically use what is called pulverized coal. That means the coal is ground up, burned, and the steam from that burning drives turbines. There's also newer integrated gasification combined cycle (IGCC) technology, which sends the gas through a combustion turbine to generate electricity, and then routes excess heat from that process to generate even more electricity through a traditional steam turbine.

In either process there are multiple points at which CCS technology could intervene. One such point is called pre-combustion. At this stage, an air separation unit produces a stream of almost-pure oxygen, which flows into a coal gasifier. Gasifiers are essentially tanks that produce synthetic gas mixtures known as syngas. The oxygen in this coal gasifier reacts with fuel to create a syngas made up of hydrogen, carbon monoxide, water, and CO2. (This form of syngas is nothing new: invented in the 1790s by William Murdoch, in the 19th century it was used to power gas lights in many towns and gained the nickname "town gas.")

CCS technology sends the syngas to a shift reactor, where it encounters steam. That steam transforms the carbon monoxide that's present into hydrogen and even more CO2. The CO2 is then captured from the gas stream, compressed, and dehydrated. That leaves it ready for transport and storage.

"Transport and storage," when applied to CCS technology, basically means sending the CO2 in a pipeline several kilometers below the earth and into rock, the idea being that it's stored there rather than released into the atmosphere to contribute to climate change. Ideal spots for this include old oil and gas fields, which have already dug into the earth, but any deep saline formation, filled with porous rock and salty water, will do. Ships could also send the CO2 to refineries in the ocean. The idea is that the CO2 stays there for millions of years and eventually chemically binds with the surrounding rock.

The technology can also be used post-combustion and with oxygen-based fuel. Post-combustion uses a solvent to bind with CO2, which then drives it off into storage. Oxygen-based CCS burns away the CO2 in a boiler. All three work-CCS has been praised by everyone from the Intergovernmental Panel on Climate Change to the International Energy Agency. The Obama Administration invested $84 million in the technology, and in a rare act of bipartisanship, one of those investments has been trumpeted by current Energy Secretary Rick Perry. That plant, Petra Nova, is the world's first post-combustion plant and is about 30 miles southwest of Houston, where it captures 1.6 million tons of carbon dioxide each year.

The question is mostly one of cost and efficiency. CCS plants are expensive to build and maintain, and retrofitting the technology onto older plants requires an increase in power and costs. That's why there are only 21 CCS plants across the globe, according to the Carbon Capture & Storage Association. That number goes up to 38 if you include projects under construction or in developmental planning, which takes some time. A report from the Global CSS Institute estimates it could cost "$100 billion annually" to develop CCS, and that the technology represents "a classic catch-22 scenario. The only way costs can decrease is by installing a large number of CCS projects worldwide. However, the high cost of CCS is challenging project development."

The technology itself has its critics, too. While CCS can effectively capture around 90 percent of the CO2 produced at power plants, some people point to the fact that coal has so many pollutants that no singular technology can capture all of them. They point to mercury, nitrogen oxide, and other poisonous contaminants that coal plants could still produce even if they're not pumping out CO2. The IEA estimates that the global storage rate could exceed 7 gigatons of carbon dioxide per year, which works out to a staggering 15 trillion pounds.

CCS offers a viable alternative to modern coal plants because even as global fossil fuel demands drop steadily, every day the industry exists is one where it could be polluting less. The IEA "has found that the world needs to capture and store almost 4,000 million tonnes per annum (MTPA) of CO2 in 2040 to meet" a scenario where the Earth's temperature rises only 2 degrees C, according to last year's Global Status of CCS report. "Current carbon capture capacity for projects in operation or under construction sits at approximately 40 MTPA," a paltry figure in comparison.

"The numbers speak for themselves," the report says. "It means that there is a lot of ground to make up."

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Carbon capture and storage works, but is expensive to build or to retrofit onto old plants. * We'd need to do a lot more capturing and storing to make a difference in battling worldwide carbon emissions. * There are other dangers associated with burning coal, too.

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Will a Plant-based Diet Reduce Global Warming?

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Will a Plant-based Diet Reduce Global Warming?

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Roger HarrabinBBC environment analyst, Geneva

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Plant-based diet can fight climate change - UN

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A major report says the West’s high consumption of meat is fuelling global warming.

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Carbon Capture and Storage (CCS) is a technology that can capture up to 90% of the carbon dioxide (CO2) emissions produced from the use of fossil fuels in electricity generation and industrial processes, preventing the carbon dioxide from entering the atmosphere.

Furthermore, the use of CCS with renewable biomass is one of the few carbon abatement technologies that can be used in a 'carbon-negative' mode - actually taking carbon dioxide out of the atmosphere.

The CCS chain consists of three parts; capturing the carbon dioxide, transporting the carbon dioxide, and securely storing the carbon dioxide emissions, underground in depleted oil and gas fields or deep saline aquifer formations.

First, capture technologies allow the separation of carbon dioxide from gases produced in electricity generation and industrial processes by one of three methods: pre-combustion capture, post-combustion capture and oxyfuel combustion.

Carbon dioxide is then transported by pipeline or by ship for safe storage. Millions of tonnes of carbon dioxide are already transported annually for commercial purposes by road tanker, ship and pipelines. The U.S. has four decades of experience of transporting carbon dioxide by pipeline for enhanced oil recovery projects.

The carbon dioxide is then stored in carefully selected geological rock formation that are typically located several kilometres below the earth's surface.

At every point in the CCS chain, from production to storage, industry has at its disposal a number of process technologies that are well understood and have excellent health and safety records. The commercial deployment of CCS will involve the widespread adoption of these CCS techniques, combined with robust monitoring techniques and Government regulation.

ZEP - The Hard Facts behind Carbon Capture and Storage

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Carbon Capture and Storage (CCS) is a technology that can capture up to 90% of the carbon dioxide (CO2) emissions pro­duced from the use of fossil fuels in electricity generation and industrial processes, preventing the carbon dioxide from entering the atmosphere.

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Reducing methane producing bacteria in cows

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Reducing methane producing bacteria in cows

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The cows grazing peacefully in the vicinity of New Zealand's farming science research institute AgResearch look much like any other. They plod slowly around the pastures, heads bowed as they tear up mouthfuls of grass and let out soft, low moos.

But some of these animals are not like the cattle you might find on other farms. Away from view, inside the hard-working stomachs of these cows, an experiment that could potentially change the planet is taking place.

They have been given a vaccine against certain gut microbes that are responsible for producing methane as the animals digest their food. Methane is one of the most egregious of greenhouse gases, roughly 25 times more potent at trapping heat than carbon dioxide.
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AgResearch's aim is to develop this vaccine, along with other anti-methane methods, in an effort to allow us to continue eating meat and dairy products while lessening the impact the livestock industry has on the environment. Beef without blame, you might say; and cheese with a clear conscience.

Estimates vary, but livestock are reckoned to be responsible for up to 14% of all greenhouse emissions from human activities. Alongside carbon dioxide, farming generates two other gases in large quantities: nitrous oxide from the addition of fertilisers and wastes to the soil, and methane. The latter is largely belched out by ruminants - principally sheep and cattle - and accounts for more than a third of the total emissions from agriculture. The average ruminant produces 250-500 litres of methane a day. Globally, livestock are responsible for burping (and a small amount from farting) the methane equivalent of 3.1 gigatonnes of carbon dioxide into the atmosphere annually.

But the scientists at AgResearch hope it may be possible to reduce the contribution livestock farming is making to global warming.

The methane produced by ruminants comes from some 3% of the vast number of microbes that live in the rumen

Their approach builds on work by Sinead Leahy, a microbiologist at AgResearch who is currently on secondment to the New Zealand Agricultural Greenhouse Gas Research Centre. The methane produced by ruminants comes from some 3% of the vast number of microbes that live in the rumen, the first section of the gut. The guilty organisms belong to an ancient group called the archaea, and they are capable of living in environments where there is no oxygen.

Through a process known as enteric fermentation, these microbes decompose and ferment the plant materials eaten by the animals, producing methane as a byproduct. To release the pressure that can build up as this gas is produced, the animals then burp it out.

To weed out the bacteria responsible, however, Leahy and her colleagues had to find a way of reproducing the oxygen-free conditions of the rumen in their laboratory. Using DNA technology, they were then able to sequence the genomes of some of the key species.

"Understanding what makes these microbes different from other types that are also important for ruminant digestion is essential," says Leahy. "Through our research we were able to look across the different types of gene sequence [in the microbes] and pick out targets [shared] across all varieties of methanogen. These then became the top targets for the development of a vaccine."

This work allowed the team at AgResearch to systematically design vaccines that targeted several microbe species at the same time.

Livestock are responsible for burping the methane equivalent of 3.1 gigatonnes of carbon dioxide into the atmosphere annually

"There are about 12 or 15 species in the subset of archaea we've tried to target," says Peter Janssen, principal investigator of the methane mitigation programme at AgResearch, who has identified various methane-producing microbes in the rumen of sheep and cows. Given by injection, the vaccine is designed to stimulate the animals' output of anti-archaea antibodies in their saliva, which is then carried into the rumen as the animals swallow.

So far only a small number of cows and sheep have been given the vaccine in trials by the AgResearch team. But the team has picked up a good level of antibody in the saliva and also in the rumen, and antibodies have been recovered from faeces as well, according to the Pastoral Greenhouse Gas Research Consortium, the major funder of the research since 2006. Having shown that vaccinated animals are actually making the antibody, they're now trying to demonstrate that this does indeed suppress the formation of methane.

To test this, animals must spend time in a respiratory chamber - a large transparent box, sealed except for a flow of fresh air. Stale air leaving the box is sampled for its methane content.

The researchers are also attempting to make measurements outside the laboratory too to better replicate what goes on in the field. One approach is to use a modified feeding trough into which the animal has to put its head to eat. "While their noses are in the feeding trough a gadget inside it can sample their breath," says Janssen. Even more cunning is a device that can be strapped on to an animal's back. "It has a little plastic tube that finishes just above the animal's nose. As the animal exhales the device sucks up a sample of its breath."

Definitive proof that vaccination cuts the amount of methane belched out by cows is still lacking

Neither technique compares for accuracy with the respiration chamber, but both serve to give a good idea of what's going in large numbers of animals. But definitive proof that vaccination cuts the amount of methane belched out by cows is still lacking.

Janssen and his colleagues do know from previous work using drugs that suppressing the methanogens yields the promised reduction. But Janssen and Leahy are not the first to try making a vaccine against methanogens, the term for any microbe manufacturing methane. Some Australian scientists had a go in the 1990s, but were unsuccessful. The AgResearch team are confident their approach, informed by genetics, will yield better results.

But vaccination isn't the only idea for cleaning up cows' breath. Animals vary in their output of methane, and some at least of this variation is attributable to genetic differences. Eileen Wall, head of research at Scotland's Rural College, explains that this offers scope for selective breeding for animals that produce less methane. She sees this not as something to be done in isolation, but as part of a wider breeding programme to develop healthier and more efficient sheep and cows - both these attributes also reduce the greenhouse gases generated per unit of meat and milk.

"Over the past 20 years we've already reduced the environmental footprint of milk and meat production in the UK by 20%," she says. Breeding for low methane would simply be an add-on to existing programmes. She and her colleagues are experimenting with methods of doing just this.

The more fibre a cow eats, the more methane it produces, but adding legumes and various oils to their diet can be helpful

Not everyone is quite so confident. Breeding animals in this way could be time-consuming and expensive, warns Liam Sinclair, who studies rumen metabolism at Harper Adams University in Shropshire, UK.

Another alternative is to feed animals on a diet less to the liking of the archaea. This can be partially effective, says Phil Garnsworthy, who specialises in dairy cow nutrition at the University of Nottingham, so long as it continues to allow the animals to go on producing milk and meat.

"You can probably reduce methane by about 20-25% by altering diet," he says. One study by researchers at the University of California, Davis, estimated it might be possible to reduce global methane emissions from cows by 15% by changing their diet. But Garnsworthy believes more may be possible. In the UK, he says, farmers mainly use grass-based silage.

"If you changed just to maize-based silage you might see a drop in methane production of 10%."

The more fibre a cow eats, the more methane it produces, but adding legumes and various oils such as linseed and soya to their diet can be helpful, adds Sinclair.

"Better quality feeding makes animals more productive, and more productive animals produce less methane," he says.

One slightly wackier approach to be proposed is to fit cows with burp-collecting backpacks

Adding seaweed to a cow's diet has also been shown to beat the methane-producing bugs.

One slightly wackier approach to be proposed is to fit cows with burp-collecting backpacks, while students at the Royal College of Art in London have designed a device that could be attached to a cow's nose ring to convert the exhaled methane into the less potent, but longer-lasting carbon dioxide.

A more realistic alternative, however, are feed additives such as ionophores, which are already used in some parts of the world to boost weight gain in animals and could also be used to inhibit the methane-producing archaea. But these are not without their problems.

Ionophores, which are classed as antibiotics, are banned for use in animals in the European Union due to concerns about how the over-zealous use of these agents in agriculture has helped to fuel drug resistance in bacteria. The ban is controversial because ionophores are not used in human medicine and act in different ways from therapeutic antibiotics.

There are other additives on offer that could also help to inhibit methane in livestock. One that has most recently gathered interest is 3-nitrooxypropanol (3-NOP), which works by lowering the efficiency of the chemical pathway along which archaea convert carbon into methane. The company behind the additive hopes for a 30% reduction.

Another option is to give cattle probiotics, or helpful bacteria, to aid their digestion. Elizabeth Latham, a former researcher at Texas A&M University and co-founder of Bezoar Laboratories, has been developing a probiotic to tackle methane from cattle and claims it can reduce emissions by 50%.

But chemical inhibitors and probiotics like this would have to be added daily to feedstuffs, and would be hard to deliver to animals fed mostly on grass. It is likely to be an expensive option. A vaccine would potentially only need to be given once, or perhaps would need just an annual booster.

Regardless of the approach used, messing with the pattern of microbial life in the gut will alter its ecology - possibly with unforeseen consequences. The gut microbiome is closely linked to health, and changing it can increase the risk of disease. There is even some association in humans between gut bacteria and mood, although it is unclear if reducing methane-producing bacteria would lead to depressed cows and sheep, or what effect this might have on their meat and milk.

Janssen thinks it is unlikely. "We don't get any signals that we're going to inhibit the ability of animals to turn grass into meat or milk," he says.

But until further tests prove that hacking the guts of livestock can cut their emissions without being detrimental to the animals or the products they are farmed for, the world will have to wait with bated breath.
-- If you liked this story, sign up for the weekly bbc.com features newsletter, called "The Essential List". A handpicked selection of stories from BBC Future, Culture, Capital, and Travel, delivered to your inbox every Friday.

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The cows that could help fight climate change

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The cows grazing peacefully in the vicinity of New Zealand's farming science research institute AgResearch look much like any other. They plod slowly around the pastures, heads bowed as they tear up mouthfuls of grass and let out soft, low moos.

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Jan Christoph Minx is head of the applied sustainability science working group at the Mercator Research Institute and professor for climate change and public policy at the University of Leeds. Gregory Nemet is an associate professor at the University of Wisconsin-Madison.
Meeting the climate goals of the Paris Agreement is going to be nearly impossible without removing carbon dioxide from the atmosphere. Simply reducing emissions from their current level is unlikely to be enough to limit global warming to well below 2 degrees Celsius. In fact, we need to remove huge amounts of carbon dioxide - billions of tons per year - to meet these goals because we have repeatedly delayed our decarbonization efforts.

At least a quarter of what we currently emit needs to be stored in trees, soil and under the Earth's crust. But we are not developing these technologies that we desperately need at the required speed. All the blame is on us: we have simply been too slow to reduce emissions, leaving us in a dire situation where we are going to have to depend on technologies that may not be available in time.

Carbon dioxide removal technologies include familiar practices such as afforestation and reforestation, where trees take up the CO2 during their growth and store it temporarily. There are also more high-tech options such as bioenergy - energy from any form of biomass such as plants, trees or other organic matter - combined with carbon capture and storage. With this approach, the biomass absorbs CO2 from the air through the process of photosynthesis; it is released again when it is burned to produce electricity in power plants but then immediately captured and stored underground. There is also the possibility of filtering CO2 directly out of the air through chemical processes.

There is no silver bullet: no single technology is likely to provide all the CO2 removal that is required. All technologies have economic and environmental constrains. They are dependent upon the establishment of policy incentives. We therefore need to explore smart technology portfolios where multiple CO2 removal technologies are deployed at more modest scales. Only diversified portfolios can help us to hedge the risks associated with CO2 removal.

Given our growing dependence on carbon dioxide removal, it is very encouraging to see burgeoning research activities. But the vast bulk focuses on early stage research. The process of innovation is often described as a sequence of stages - from basic science to applied research to demonstration projects to serving early niche markets to scaling up to a larger market, including public acceptance of inevitable side effects at widespread adoption.

Case studies on innovation show that this process typically takes decades to play out. It is a slow grind of building up and transferring knowledge as more entities become involved in the emerging technological system: not just scientists and engineers, but also companies, financiers, regulators and crucially, adopters of the technology. Little has been said about who might use the technology or what their incentives to do so might be.

A breakthrough invention in science often stimulates exuberant assumptions that shortcuts in the process of technology adoption are available. But they rarely are. The research community on carbon dioxide removal may be proceeding down a path of wishful thinking that the brilliance of the ideas behind this research will inherently create adopters and users. A revealing point is that in many studies and news articles, these technologies will be "deployed." Only rarely do we read about people "adopting" them. This top-down orientation, using military language, is bound to run into problems, especially at the massive scales involved.

Consider the experience of arguably the most dynamic low-carbon innovation so far, solar photovoltaic panels. It took 60 years after the first commercial use, the Vanguard-1 satellite in 1957, to get to the current state where solar beats coal and gas on cost in sunny places. By the 2030s, more than 10 percent of global energy supply is expected to come from solar. The first commercial direct CO2 air capture system came online last year. If air capture is to follow a similar timeline to solar, it will be low cost in 2077 and attain widespread adoption by 2100. That is far too late.

Therefore, we need two major efforts. First, we need a new emphasis from the research community on innovation beyond research and development. We need serious work on early deployment, niche markets, scale-up, demand and public acceptance.

Second, we need to implement ways to accelerate the innovation process for carbon removal to ensure that technologies are available in time at the scale we need them. Right now, national and international climate policy has done little to ensure this. Even if there are no shortcuts, we can use what we have learned from other technologies to speed things up: funding research and development continuously, government purchasing of early models, enabling the international spread of know-how, identifying spillover opportunities across technology areas and - last but not least - taking seriously the political economy of negative emissions.

But we also need a turnaround in climate policy. We need to bend the path of continued increases in greenhouse gas emissions and start an era of rapid and sustained emissions reductions right now. Only this can limit our future dependence on carbon dioxide removal technologies. At the current state of climate diplomacy, emissions reductions and carbon removal technologies can no longer be perceived as contradictions.

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Opinion | The inconvenient truth about carbon capture

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Jan Christoph Minx is head of the applied sustainability science working group at the Mercator Research Institute and professor for climate change and public policy at the University of Leeds. Gregory Nemet is an associate professor at the University of Wisconsin-Madison.

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Tesla and its competitors in the battery-powered electric vehicle market dominate debate over who will control the future of cars, but there's another kind of green transportation technology making inroads in the United States, and it is based on the most abundant resource in the universe.

Fuel cell electric vehicles (FCEVs) combine hydrogen stored in a tank with oxygen from the air to produce electricity, with water vapor as the by-product. Unlike more common battery-powered electric vehicles, fuel cell vehicles don't need to be plugged in, and current models all exceed 300 miles of range on a full tank. They're filled up with a nozzle almost as quickly as traditional gas and diesel vehicles. While fuel cell vehicles themselves only emit water vapor from their tailpipes, the Union of Concerned Scientists notes that producing hydrogen can lead to pollution. Though renewable sources of hydrogen, such as agricultural and waste sites, are increasing, the majority of the hydrogen sourced for fuel comes from traditional natural gas extraction. Still, the impact is still less than gasoline-powered counterparts.

Hydrogen power has been on the market for years but in an extremely limited capacity. There are currently 39 public hydrogen fueling stations in California (with another 25 in development), along with a couple in Hawaii. Now the East Coast is getting its own infrastructure. A handful of stations are up and running, and more are in the works in New York, New Jersey, Massachusetts, Connecticut and Rhode Island.

Commercial success, consumer challenges

Hydrogen is more established in the commercial market. There are more than 23,000 fuel cell-powered forklifts in operation at warehouses and distribution centers across the U.S. in more than 40 states, including at Amazon and Walmart facilities. There are dozens of fuel cell buses in use or planned in Ohio, Michigan, Illinois and Massachusetts, as well as California.

Consumer hydrogen refueling stations are increasing throughout the world. Toyota and Honda are teaming up with the government in Quebec to build hydrogen infrastructure in Montreal this year, and even oil-rich Saudi Arabia is getting its first station.

Toyota, the world's second-largest automaker, is the largest player in the U.S. consumer market for hydrogen fuel cell cars. Its Mirai - a hydrogen fuel cell family car - has found 5,000 buyers since it was introduced in the fall of 2015. Russ Koble, a spokesman in Toyota's environmental and advanced technology group, said the company expects sales to increase as more fueling stations open.

"Toyota has long maintained that hydrogen fuel cell technology could be a zero-emission solution across a broad spectrum of vehicle types," he said.

Toyota says the scalability of hydrogen fuel cell technology also has led to two applications for California feasibility studies in another area of interest to Tesla: semi-trailer trucks.

Honda also has made a big commitment to hydrogen. There are currently nearly 1,100 Honda Clarity Fuel Cell vehicles on the road in the U.S., said Natalie Kumaratne, a Honda spokeswoman. Honda only offers the Clarity Fuel Cell in California for lease - it offers battery electric power and hybrid versions of the car for lease or sale. Out of the 20,174 total Claritys sold or leased in 2018, 624 were fuel cell variants, 948 were battery-electrics, and 18,602 were the plug-in hybrid.

Honda and Toyota have teamed up with a subsidiary of Shell Oil to build new hydrogen fueling stations in California. Two have been built thus far, and five are in the works, Kumaratne said. The company is advocating for stations in the Northeastern United States, with several in development. "Partnering with other hydrogen fuel cell manufacturers and industry influencers makes sense. We all have skin in the game," she said.

Hyundai, which currently has 220 hydrogen fuel cell vehicles on the road in the U.S.,also sees sales increasing. "We expect the Northeast to be the next big region of hydrogen infrastructure growth," said Derek Joyce, spokesman for the Korean manufacturer's product and advanced powertrain group. The company just introduced the Nexo to the U.S. The EPA rates the midsize crossover's range up to 380 miles, longer than any battery-powered EV on the market.

As of Feb.1, just over 6,000 fuel cell electric vehicles had been sold and leased in the U.S., double Japan, the next biggest market.

Musk on hydrogen 'fool cells'

Tesla co-founder and CEO Elon Musk has dismissed hydrogen fuel cells as "mind-bogglingly stupid," and that is not the only negative thing he has had to say about the technology. He has called them "fool cells," a "load of rubbish," and told Tesla shareholders at an annual meeting years ago that "success is simply not possible."

Musk found a surprising source of support in 2017, when Yoshikazu Tanaka, chief engineer in charge of the Mirai, told Reuters, "Elon Musk is right - it's better to charge the electric car directly by plugging in." But the Toyota executive added that hydrogen is a viable alternative to gasoline. Toyota chairman Takeshi Uchiyamada told Reuters at the same Tokyo auto show in 2017, "We don't really see an adversary 'zero-sum' relationship between the EV (battery powered electric vehicle) and the hydrogen car. We're not about to give up on hydrogen electric fuel-cell technology at all."

The auto industry as a whole has not embraced Musk's battery-or-bust vision of the future. A 2017 survey of 1,000 senior auto executives conducted by KPMG found they believe hydrogen fuel cells have a better long-term future than electric cars and will represent "the real breakthrough" (78 percent), with the auto executives citing the short refueling time of just a few minutes as a major advantage. Sixty-two percent told KPMG that infrastructure challenges will result in the battery-powered electric vehicle market's undoing.

In California, debate continues over whether the subsidies offered by the state to jump-start the fuel cell market have paid back the investment as judged by the limited use of refueling stations and lack of profits. California is committed to the effort begun under former Gov. Jerry Brown to fund renewable energy initiatives, which included a $900 million zero-emissions vehicles plan and funding for electric vehicle charging infrastructure, including 200 hydrogen stations by 2025.

We could see hydrogen fuel cell systems that cost four times less than lithium-ion batteries, as well as providing a much longer range.

chair of physical chemistry at Lancaster University

GM has not released a fuel cell vehicle for the consumer market, but it has a joint venture with Honda to produce fuel cell stacks at a Michigan plant, a deal that started in 2013 and expanded in 2017, when both companies said the Michigan plant where the fuel stacks are being made could produce vehicles starting in 2020.

Ford has experimented with fuel cell variants of its Focus and Fusion cars, as well as the Edge crossover, but does not offer any such vehicles for sale.

"With a steadily growing share of renewable energies, hydrogen fuel cells could play a role in the future," said a Ford spokesman. "In terms of a widespread market launch, however, the battery is currently in a superior position to the fuel cell - not least because of the cost situation and the available infrastructure. Our work will continue to focus on electrification as we monitor hydrogen's progress. We have no current plans to offer hydrogen fuel cell vehicles."

Fiat Chrysler does not have a fuel cell vehicle on sale in the U.S., but for 15 years it has supported research led by Professor David Antonelli, the chair of physical chemistry at Lancaster University in the U.K., that could bring costs down for the technology. His team is working with a material that enables fuel tanks to be smaller, cheaper and more energy-dense than existing hydrogen fuel technologies as well as battery-powered vehicles.

"The cost of manufacturing our material is so low, and the energy density it can store is so much higher than a lithium-ion battery, that we could see hydrogen fuel cell systems that cost four times less than lithium-ion batteries, as well as providing a much longer range," said Antonelli. The technology has been licensed to a for-profit company called Kubagen, set up by Antonelli.

Car model and refueling prices remain big issues

Safety is a concern, as hydrogen is flammable, but so is gasoline and lithium-ion batteries. The transportation of hydrogen for use at refueling stations poses additional safety risks - stations use sensors to monitor for leaks. There have not been serious incidents reported in California, and the industrial sector has been transporting hydrogen for decades.

According to the National Fire Protection Association, alternative-fueled vehicles, a category that includes both hydrogen fuel cell and battery-powered electric, are not more hazardous than traditional internal combustion engines. The NFPA's statistics reveal that approximately every 3 minutes there is a car fire in the U.S. from an internal combustion engine vehicle.

The biggest hurdle, however, may be cost.

The average price for hydrogen fuel in California is about $16/kg - gasoline is sold by the gallon (volume) and hydrogen by the kilogram (weight). To put that in perspective, 1 gal of gasoline has about the same amount of energy as 1 kg of hydrogen. Most fuel cell electric cars carry about 5 kg to 6 kg of hydrogen but go twice the distance of a modern internal combustion engine car with equivalent gas in the tank, which works out to a gasoline-per-gallon equivalent between $5 and $6.

Hydrogen fuel cell cars now average between 312 miles and 380 miles in range, according to the EPA. They will cost about $80 to refuel from empty (most drivers don't let the tank run down to empty before they refuel, so end up refueling at a cost of $55 to $65). That cost is currently being paid for by automakers, who provide lessees with prepaid cards for three years of fueling, up to $15,000. In California, which has the nation's highest gas prices, filling up a conventional car with a large gas tank can cost $40 or more.

Kelley Blue Book estimates annual fuel costs for the Toyota Mirai, Honda Clarity Fuel Cell and Hyundai Nexo at $4,495, which is three to four times the cost of gas-powered alternatives.

"We recognize the automakers can't keep paying for fuel, and we see the line of sight to get there, but it is a volume game and we need to hit a critical mass," said Shane Stephens, principal and chief development officer at FirstElement Fuel, which runs 19 of the 39 hydrogen refueling stations in California and is developing 12 of the 25 additional stations for the state. His company's near-term target is $10/kg, which would equate to roughly $4/gal of gas. "That is a good near-term acceptable number to hit in the next three to five years and get people off automaker-subsidized fuel," Stephens said.

The biggest problem: The cars remain expensive. Nexo, for instance, is the most expensive Hyundai on sale in the U.S., with a starting price of $59,345 (starting prices for the brand's comparably-sized Santa Fe start at $24,250). The Toyota Mirai and Honda Clarity fuel cell models have a similar MSRP in the $59,000 range. These car purchases are eligible for government rebates - in California there is a $5,000 tax rebate available.

Leasing has been a popular consumer choice for fuel cell and battery electric cars because the technology is new and early adopters don't want to be tied into a current model for a long time as the technology advances and efficiency improves.

As with any new technology, fuel cell costs should come down if the market grows and achieves economies of scale in manufacturing and infrastructure. "Honda has a long-term commitment to hydrogen, but you can't sell vehicles without infrastructure," Kumaratne said.

Stephens said if the market can reach "a few hundred thousand cars" in California, it can be cost-competitive with gasoline. That represents a big jump from the 6,000 cars sold so far, but most new auto markets start with limited production runs. Toyota has said it plans to increase production from 3,000 Mirai units per year to 30,000 cars by 2021. "That is a tenfold magnitude increase."

"A few hundred thousand cars in California is not that far off. And that is just Toyota," Stephens said. "This is not about subsidizing the entire growth of the infrastructure but just helping us get over the hump, and that is on the horizon. If we get to a few hundred thousand cars, we can really start to sunset government subsidies and be self-sustaining."
Correction: Hydrogen is the most abundant resource in the universe. Due to an editing error, an earlier version of this article misstated that fact.

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Elon Musk says the tech is 'mind-bogglingly stupid,' but hydrogen cars may yet threaten Tesla

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Tesla and a growing list of competitors in the electric vehicle market dominate debate over the future of cars and recharging networks, but there's another kind of green transportation making inroads, based on the most abundant resource in the universe: hydrogen fuel cells.

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The disarming case to act right now on climate change | Greta Thunberg

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Greta Thunberg and George Monbiot make short film on the climate crisis

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Greta Thunberg full speech at UN Climate Change COP24 Conference

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It has been suggested that if everyone on the planet consumed as much as the average US citizen, four Earths would be needed to sustain them. But where does this claim originate, and how is it calculated?

The world's seven billion people consume varying amounts of the planet's resources. Compare the lifestyle of a subsistence farmer with that of a wealthy city-dweller in a developed country. More land is required to grow the city dweller's food, more materials are used to build the city dweller's home and workplace, more energy is required for transport, heating and cooling.

So it's obvious that Americans consume more, on average, than the people of less developed countries. But the claim that four Earths would be needed if everyone lived like Americans is still a striking one.

It has been recurring on social media at least since 2012, when science writer Tim De Chant produced this infographic illustrating how much land would be required if seven billion people lived like the populations of nine selected countries from Bangladesh to the United Arab Emirates.

De Chant was using a subset of data produced by the Global Footprint Network (GFN), which has been attempting the tricky business of measuring the impact of humans on the planet since 2003.

"Ecological footprinting" is where researchers look at how much land, sea and other natural resources are used to produce what people consume - how many potatoes they eat, how much milk they drink, the cotton that goes into the shirts they wear and so on.

They do this by using published statistics on consumption and the amount of land or sea used to produce the quantity of goods consumed.

More or Less: Behind the stats

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"It's a book-keeping approach for resources," says GFN director and co-founder Mathis Wackernagel.

The key questions for GFN, he says, are: "If there is one planet - how much planet is available per person and how much planet do we use per person."

The answers are expressed in an unusual unit - the global hectare, defined as a biologically productive hectare with world-average bioproductivity.

The average American, says GFN, uses seven global hectares, compared to a global average of 2.7, according to the most recent GFN figures (based on data from 2011). It's this figure of seven global hectares that allows Wackernagel and his colleagues to calculate that it would take four Earths - or to be precise, 3.9 Earths - to sustain a population of seven billion at American levels of consumption.

However, the US does not consume the most on this measure. It is in fact ranked fifth among countries with a population of one million or more. Kuwait comes top with 8.9 global hectares (5.1 Earths), followed by Australia (4.8 Earths), the United Arab Emirates (4.7 Earths) and Qatar (4.0 Earths). The others in the top 10 are Canada, Sweden, Bahrain, Trinidad and Tobago, and Singapore. The UK is 32nd on the list (2.4 Earths).

These figures don't say anything about sustainability of cropland, such as the erosion of soil
Linus Blomqvist, Breakthrough Institute

How useful are these figures?

One curious thing to note is that according to the Global Footprint Network, the world's population is currently using not one, but one-and-a-half Earths.

That's because it takes account of carbon emissions. The forests and oceans of the world absorb a lot of carbon dioxide, but we are currently emitting more than the planet can handle - and Wackernagel's team has calculated how much extra land and sea we would need to absorb it. They estimate that we need an extra half a planet.

If we now look again at the average American footprint - two-thirds of that is made up of carbon emissions.

This means that for the four Earths we would need if everyone consumed like an American, more than two-and-a-half of those would be needed just to absorb carbon dioxide.

This calculation has its critics.

"It seems a little odd to convert what's happening in the atmosphere into a proxy measure and pretend you're measuring land when you're not," says Fred Pearce, environment correspondent for New Scientist magazine.

But Mathis Wackernagel says it is important to include carbon emissions in the calculation to capture the "total package" of our activity.

Another criticism - made, for example by Linus Blomqvist, Director of Conservation at the Breakthrough Institute in California - is that there is insufficient data from many parts of the world to create meaningful ecological footprint estimates. Researchers just don't know how sustainable some agricultural practices are, and therefore to what extent resources are being overused.

"Our critique is that these figures don't say anything about sustainability of cropland, such as the erosion of soil," Blomqvist says.

Wackernagel accepts this criticism, to an extent.

"I would be perfectly blunt - our numbers are certainly wrong. I'm convinced our numbers are underestimates.
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"There are aspects on which no good data exists that we don't include, so our demand on nature is larger."

While these figures may not be perfect, Wackernagel says that governments can find them useful as a way of thinking about policies on the environment.

For example, Switzerland publishes ecological footprint estimates on its Federal Statistics Office website. The UK, meanwhile, has formed a Natural Capital Committee to study how the country consumes its natural resources and how long, at current rates, they will last.

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It has been suggested that if everyone on the planet consumed as much as the average US citizen, four Earths would be needed to sustain them. But where does this claim originate, and how is it calculated? The world's seven billion people consume varying amounts of the planet's resources.

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7 Billion: How Did We Get So Big So Fast? | SKUNK BEAR

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Drilling Ice Cores

Introduction

Ice cores are drilled in glaciers and on ice sheets on all of Earth's continents. Most ice cores, however, come from Antarctica and Greenland, where the longest ice cores extend to 3 kilometers-over 2 miles-or more in depth. Ice cores from the cold interior regions of polar ice sheets provide exceptionally well-preserved and detailed climate records. This is because the lack of melt at these locations does not corrupt the record of trapped gases or blur the record of other impurities. The oldest continuous ice core records extend to 130,000 years in Greenland, and 800,000 years in Antarctica.

Ice cores are typically drilled by means of either a mechanical or thermal drill. Both types of drills incise an annulus, or circle, around a central, vertical core.

A mechanical drill is simply a rotating pipe, or drill barrel, with cutters at the head. When the drill barrel is rotated, the cutters incise a circle around the ice to be cored until the barrel is filled with ice. The cuttings-also referred to as chips -are transported to a chip chamber in the drill. The drill barrel is rotated by either physical force, as in the case with simple hand augers, or with an electromechanical motor drive, as in the case with sophisticated electromechanical drills. Thermal drills, in contrast, use a ring-shaped heating element to melt an annulus around the ice to be cored and the melt water is stored in a tank in the drill.

At sites where the ice is well below freezing, such as the interiors of the polar ice sheets, mechanical drills must be used. In contrast, thermal drills are particularly effective at coring through warmer ice (e.g., ice approximately above -10°C) and are frequently used on mid- or low-latitude glaciers. On many non-polar glaciers, however, ice conditions can vary from "cold" ice to "warm" ice, requiring both mechanical and thermal drilling to retrieve the best possible core quality over the entire depth interval that is drilled.

The length of the drill barrel determines the maximum length of a core section that can be retrieved in a single drill run. Ice cores are typically retrieved in sections that are 1 meter to as much as 6 meters in length, and typically 50-132 millimeters in diameter. The collection of a long ice core therefore requires many repeated cycles-or drill runs -of lowering the drill, cutting a core section, raising the drill back to the surface, removing the drilled ice core section from the barrel, and readying the drill to go back down the hole to retrieve more ice.

Hand Augers

When scientists are interested in collecting ice cores from the top 20- to 30-meters of a glacier or ice sheet a hand auger is commonly used. In the United States, there are four types of hand augers commonly used: the SIPRE auger, the PICO auger, the Kovacs auger, and the IDDO auger.

The hand auger is the most basic of the mechanical drills and consists of a barrel and cutting head. The barrel is typically 1 meter long and with an internal diameter of either 3 or 4 inches. A protruding thread spiraling up and around the barrel is used to remove the ice chips from the cutting face. The cutter head includes 2 or 3 hardened steel or carbide teeth, and the protrusion of the teeth can be adjusted to control the depth of cut. If the depth of cut is set too small, the cutter head will skid over the ice surface rather than cut down into it. If the depth of cut is set too large, the teeth will become lodged in the ice halting the drilling altogether.

The hand auger is driven from the surface by a series of extensions that are added as drilling proceeds into the ice. The hand auger, like all other coring drills, has to be retrieved each time a core section is recovered. Hand augers are either driven by hand, using an attached T-bar, or adapted to use a powered motor drive or drill. The maximum depth to which a hand auger and its extensions can be raised and lowered in and out of a borehole by two people is ~20-30 meters. A mechanical winch/lifting system is generally required at greater depths. The depth limit for hand augers is limited by the strength and flexibility of the extension rods to ~40 meters.

Shallow Ice Coring

When depths greater than ~40 meters need to be reached, ice coring projects typically use specialized electromechanical or electrothermal drills that hang on a cable. The cable runs from a winch over a top wheel-called a sheave -on a vertical tower. The cable has electrical wires inside that power the drill and allow for operation of the drill from the surface. This type of drilling is referred to as cable-suspended drilling, and is the preferred drilling method when drilling intermediate and deep ice cores. While several early ice drilling projects used conventional surface-driven rotary and wireline drill rigs to collect ice cores, the use of specialized cable-suspended drills to collect ice cores is now the common practice. Cable-suspended drill systems are preferred because they significantly decrease the weight of the drill and its power consumption, shorten the time of travel in and out of the borehole, and simplify the process of removing the cuttings from the borehole.

While most cable-suspended drills are similar in design, the details do vary from drill to drill, often with specific projects and field sites in mind. For instance, due to the remoteness and high-altitude of most non-polar glaciers, the drills used at these locations must be lightweight and of modular design to allow for transportation by helicopter, or for glaciers located above the range of helicopter operation (e.g., above 5500 meters elevation), transportation by either porters or pack animals. In the polar regions, extremely low temperatures and very remote and logistically complicated field sites influence the design of the drills used.

Below are general descriptions for two types of cable-suspended ice coring drills: electromechanical and electrothermal. More detailed information can be found by reading the literature noted in References and Links.

Cable-Suspended Electromechanical Drills

There are many versions of the electromechanical (EM) drill used in ice coring. The portion of the drill that goes down the borehole is called the sonde, and its only physical connection to the surface is through its suspending cable. The components of the sonde typically include a cutting head that is attached to an inner barrel, an outer barrel, a motor to rotate the inner barrel, and an anti-torque system that counteracts the rotational cutting action.

The cutting head typically has 3 to 4 hardened steel or carbide teeth that shave ice in an annulus around the central, vertical core. The protrusion of the teeth and their subsequent depth of cut into the ice are controlled with small, adjustable buttons called shoes that are located on the bottom face of the cutter head. The vertical distance between the bottom of the shoes and the cutters determines the depth of cut into the ice.

A protruding thread, also referred to as flights, spiraling up and around the inner barrel is used to remove the ice chips from the cutting face. As the cutting head spins around and the cutters shave the ice, the chips are transported up the flights between the two barrel sections. The inner barrel spins while the outer barrel stays stationary, and it is that difference that actually drives the chips upward along the flights to the top of the sonde thus removing them from the cutting face.

Most cable-suspended EM drills are designed as double-barreled (e.g., an inner barrel and an outer barrel) for several reasons. Double-barreled drills collect ice chips more efficiently than single-barreled drills, and the added stiffness of the double-barreled design typically results in fewer breaks in the cores that are drilled, as well as straighter boreholes.

Because of the great depths that can be reached, cable-suspended EM drills are often used with a drilling fluid to prevent closure of the borehole at depth (see Deep Ice Coring).

The anti-torque system on EM drills often consists of three or four leaf springs that anchor the sonde to the wall of the borehole. If there is no anti-torque section, the motor will cause the entire EM drill and cable to rotate inside the borehole, preventing the ice from being cut and causing the cable to become wrapped.

When a drill run is finished and the barrel is full with ice, the core is typically held in the inner barrel by spring-loaded lever arms called core dogs that grip, break, and retain the ice core when the cable and sonde is pulled upward. The sonde is then hoisted to the surface with the winch and the core removed. In many modern cable-suspended EM drill systems, the sonde and tower both tilt from the vertical position to the horizontal position to aid in the removal of the ice core and the chips.

Cable-Suspended Electrothermal Drills

The electrothermal (ET) drill uses a ring-shaped heating element in the coring head to melt an annulus around the ice to be cored, rather than shaving it away with cutters like the EM drill. The electrical power to heat the coring head is fed through the drill's suspending cable.

The meltwater that is produced by ET drills may either be left down the hole or stored in a tank within the sonde. When englacial temperatures are low and there is concern that the meltwater may re-freeze causing the borehole to close-in on itself, the meltwater is either stored in a tank in the sonde and emptied once on the surface, or the meltwater is mixed with an antifreeze solution and left down the hole. For depths below which borehole closure in an open hole is a concern, the meltwater is left down the hole to help prevent hole closure. If re-freezing is also a concern, the meltwater that is left down the hole is mixed with an antifreeze solution.

ET drills have only one barrel, so the size of the borehole is generally smaller than a borehole from an EM drill for a similar diameter ice core. ET drills are mechanically much simpler than EM drills because they contain fewer moving parts. They also do not require an anti-torque system since there is no rotational cutting action. ET drills are also generally more compact in size and weight than EM drills, in part because no chip storage is required.

While ET drills are particularly effective at coring through warmer ice (e.g., ice approximately above -10°C) they have also been used to drill in cold ice in Antarctica. The main disadvantage of using ET drills to drill cold ice (e.g., ice approximately below -15°C) is the large thermal shock that occurs to the core, which is bad for many types of measurements that are typically made on ice cores.

Deep Ice Coring

For depths below which borehole closure in an open hole is a concern, a drilling fluid is used to make sure that the pressure in the borehole is approximately the same as the surrounding ice to prevent closure of the borehole. The plastic nature of ice, which is what produces the hole closure, is strongly temperature dependent and therefore the depth at which a drilling fluid is required to prevent borehole closure is also strongly temperature dependent. A drilling fluid may be required as early as 100 meters depth on glaciers that are at their melting point (e.g., temperate glaciers), or as deep as 1000 meters on the high, extremely-cold interior plateau of East Antarctica. In general, drilling fluids are used whenever depths greater than ~300 meters are required.

Deep ice core drilling, that is, to depths where the use of a drilling fluid is required, is typically carried-out using cable-suspended EM drills that use a pump to circulate both the drilling fluid and the chips through screens that separate the chips from the fluid.

The deepest ice core records come from Antarctica and Greenland, where the very deepest ice cores extend to 3 kilometers (over two miles) in depth. The oldest continuous ice core records extend to 130,000 years in Greenland, and 800,000 years in Antarctica. The United States (U.S.), Denmark, Russia, France, Germany and Japan have all developed highly specialized cable-suspended EM drills for the purpose of recovering ice cores to depths of 2 kilometers or more.

The most recent U.S. deep ice coring project is the West Antarctic Ice Sheet Divide (WAIS Divide) project in West Antarctica, funded by the National Science Foundation. After seven field seasons of preparation and drilling, the WAIS Divide project reached its final depth goal of 3,405 meters on December 31, 2011, completing the longest U.S. ice core ever recovered from the polar regions.

The WAIS Divide ice core was drilled using the U.S. Deep Ice Sheet Coring Drill (DISC Drill). The DISC Drill is a cable-suspended EM drill system capable of cutting and retrieving cores of ice-in 3 meter long sections-to depths of ~4,000 meters. The sonde consists of a cutter head, a core barrel in which the core is collected, screens to remove chips from the drill fluid, a motor and transmission to drive the cutter head, a pump to circulate ice cuttings in the drill fluid through the sonde, an instrumentation/control section, an anti-torque section to stabilize the drill in the borehole, and the mechanical, electrical power, and fiber optic terminations of the cable. The 15 mm diameter cable suspends the drill sonde in the borehole and also provides electrical power and fiber optic communication to the sonde. The drill's cutter head contains four razor-sharp cutters that shave out an annulus of ice, which the 14 meter long sonde slides down into. As the sonde slides down into the annulus it slides over the core, which is 12.2 centimeters in diameter. When a cable pulls up the sonde, four cams grab the core and fracture it. After the sonde is pulled back to the surface, the sonde and tower are tilted as one unit from a vertical to a horizontal orientation and the core is pushed out.

The 3,405 meter long core was drilled over the course of six field seasons. Typically, ~40 days were available each season for drilling, and drilling operations were conducted on a 24-hours per day, 6-days per week schedule by a crew of ~9 drillers (3 shifts of 3 drillers/shift) each season.

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The NSF-ICF is a facility for storing, curating, and studying meteoric ice cores recovered from the glaciated regions of the world. It provides scientists with the capability to conduct examinations and measurements on ice cores, and it preserves the integrity of these ice cores in a long-term repository.