# data[].attributes.body
"Using studies of tree rings going back centuries, scientists have unearthed clear evidence that the rise of human-generated greenhouse gases was having an effect on global drought conditions as early as 1900."

# data[].attributes.attachment_link.readable_text
Using studies of tree rings going back centuries, scientists have unearthed clear evidence that the rise of human-generated greenhouse gases was having an effect on global drought conditions as early as 1900.

A new, first-of-its-kind study by scientists at Columbia University's Earth Institute, published Wednesday in the journal , largely confirms what climate models have shown. In the absence of strong historic data on precipitation, those computer models forecast not only future scenarios, but shed light on historical trends.

The dovetailing of the tree-ring studies, which correlate to soil moisture, with climate models gives scientists the assurance that the computer models are, in fact, correct, they say.

"These tree-ring reconstructions let us go back in time and get a picture of global drought conditions for hundreds of years before the Industrial Revolution," said Kate Marvel, an associate research scientist at the Earth Institute and NASA's Goddard Institute for Space Studies and the lead author of the study.

Marvel said that the results, while not unexpected, are nonetheless gratifying. "As a scientist, you are always surprised whenever anything you do works," she said in a phone interview. "There were increased greenhouse gases in the early 1900s and the models say, 'Hey, you should see a signal.' But the fact that the signal is really clear in the models and apparent in the tree rings is pretty amazing. We can argue for a detectable human influence."

Fingerprinting droughts

Scientists have long predicted that as global warming increases, certain regions of the world, such as the southwestern United States, will become drier, while other areas will grow wetter. But the Intergovernmental Panel on Climate Change has cautioned against ascribing particular rain or drought events to human activity.

The tree-ring data analyzed in the study highlight three periods over the past 120 years in which a human fingerprint on drought and moisture is, to varying degrees, evident. The first, from 1900 to 1949, reveals the strongest signal, mirroring climate models showing that parts of the world from Australia to the Mediterranean were drying as other regions, including swaths of central Asia, were moving in the opposite direction.

The next period, from 1950 to 1975, is more murky, though the tree rings again match the climate models. The study posits that aerosols -particles from car exhaust and the burning of fossil fuels-were so abundant before the advent of anti-pollution measures that they served to block sunlight and thus cool the planet, even while tracking the uptick in greenhouse gases.

The last period, from 1981 to 2017, saw a reappearance of the human influence on drought and moisture. The study concludes that this signal is "likely to grow stronger in the next several decades," adding that the "human consequences of this, particularly drying over large parts of North America and Eurasia, are likely to be severe."

The study relied on a series of drought atlases containing tree-ring data from around the globe over the past two millennia. The atlases were assembled primarily by Edward Cook, a scientist at Columbia's Lamont-Doherty Earth Observatory and the father of Benjamin Cook, one of the study's co-authors.

Gregory R. Quetin, a postdoctoral researcher in Stanford's Department of Earth System Sciences, who was not involved in the study, called the findings "powerful," pointing to the climate record encoded in the tree rings.

"The trees are responding to temperature and the presence of, or lack of, rainfall," he said, "so they give you these observations-and another path of evidence that this is occurring."

Abigail Swann, an atmospheric scientist at the University of Washington, agreed: "It's a creative way to leverage that information from the past."

Lisa W. Foderaro was a staff reporter for more than 30 years at the New York Times, where she covered the environment in New York, among other beats. She has written extensively on climate change, conservation, water quality, wildlife, and invasive species. She has also contributed toAudubon andAdirondack Life magazines.

# data[].attributes.attachment_link.title
Climate change has contributed to droughts since 1900-and may get worse

# data[].attributes.attachment_link.description
Using studies of tree rings going back centuries, scientists have unearthed clear evidence that the rise of human-generated greenhouse gases was having an effect on global drought conditions as early as 1900. A new, first-of-its-kind study by scientists at Columbia University's Earth Institute, published Wednesday in the journal , largely confirms what climate models have shown.

# data[].attributes.body
"The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased".

# data[].attributes.attachment_link.readable_text
The globe is warming. In 2013, the Intergovernmental Panel on Climate Change (IPCC) concluded in its authoritative fifth assessment report that "Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased". They also stated that "Human influence on the climate system is clear." How did they reach those sobering conclusions?

Scientists from NASA and other research institutions around the world have been routinely collecting temperature data from a wide number of locations all over the planet. Their records of Earth's average temperature go back to the 1880s, the earliest year for which reliable instrumental records were available worldwide. The National Climatic Data Center (NCDC), which is part of the National Oceanic and Atmospheric Administration (NOAA), has maintained global average monthly and annual records of combined land and ocean surface temperatures for more than 130 years. These data show that temperatures have climbed to more than 1.8°F (1°C) above pre-industrial levels as of 2015, and the long-term global upward trend is clear and unambiguous (Figure 1)

The 2013 Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) stated that "each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850". Data also shows that, globally, the last decade has been the warmest ever recorded - 2015 was the warmest year on record according to NASA and NOAA, and 2016 is on track to beat 2015.

Adding to the evidence of direct temperature measurements, studies by independent teams of researchers indicate that the planet is undergoing one of the largest climate changes in Earth's history, and also one of the fastest in the past 65 million years. Not only that, the current warming is projected to occur at a rate 10 times faster than any change over that period.

But how do we know Earth's temperature before 1880?

To understand climate trends from the past, before reliable measurement methods existed, climate experts rely on biological or physical archives - known as "proxies" - that preserve past temperature. Tree rings, coral skeletons, and glacial ice cores (Figure 3) are proxies for annual temperature records, while boreholes (holes drilled deep into Earth's crust) can show temperature shifts over longer periods of time.

The way scientists measure and interpret various proxies depends on the information each proxy provides. For example, to obtain temperature records from tree rings, scientists drill cores into several trees that are growing in a region. They identify site-specific factors that influence tree growth such as temperature, precipitation, altitude, and tree age, and then compare these factors against the width or density of the tree rings over the lifetime of the tree. Once researchers are confident about how local tree growth correlates to air temperature, they then seek out older trees in the region that are preserved (perhaps in a local swamp or lake). By matching rings from trees that partially overlap life spans, scientists can construct a continuous climate record over thousands of years.

Ice cores have bands of light and dark areas with traces of various substances, which can be analyzed as to composition and age, yielding important information about the environmental conditions throughout time. Antarctic ice core records vividly illustrate that atmospheric carbon dioxide (CO2) levels today are higher than levels recorded over the past 800,000 years (Figure 4).

Atmospheric CO2 levels have risen 30 percent in the last 150 years, with half of that rise occurring only in the last three decades. It is a well-established scientific fact that CO2 (and other gases emitted from industrial and agricultural sources) traps heat in the atmosphere, so it is no surprise that we are now witnessing a dramatic increase in temperature.

Reconstructions of past climates help us build accurate projections of how future climates will be affected by global warming

Much as the Air Force builds computer programs to simulate flight under different conditions, climate scientists build computer programs to help simulate global climate. These computer programs, called General Circulation Models (GCMs), use various assumptions about physical, chemical, and biological processes that occur within Earth's atmosphere and oceans and on its land surfaces. To ensure accuracy, each model is checked to see if it generates results that correctly reproduce the past and current climate. Once accuracy is established, the computer program can then be used to explore the likely future climate if, for example, we double the atmospheric concentration of carbon dioxide.

Earth's climate in the past has been warmer and colder than it is now (Figure 5). Over the past million years, shifts in orbital cycles influenced the amount of sunlight falling on the northern hemisphere and played a major role in the waxing and waning of ice ages. Whenever atmospheric carbon dioxide increased naturally (either as a direct cause or as an amplifier, see this study), global surface temperature increased further. This held true even when local temperatures in the northern hemisphere and southern hemisphere might be out of phase due to factors including ocean circulation. Past climate evidence informs just how powerful carbon dioxide is. All else being equal, increases in atmospheric carbon dioxide lead to warmer global average surface temperatures. That is a proven relationship known since at least 1861 and confirmed throughout the years.

This is also true of the current warming trend--an increase in carbon dioxide is leading to an increase in temperatures. However, in this current warming episode, the increase in CO2 is largely due to human emissions from the burning of oil, coal, and gas ( IPCC Fifth Assessment Report).

The "hockey stick" graph and its significance

The "hockey stick" graph, created by a group of climate researchers in the late 1990s, reflects average Northern Hemisphere temperature changes over the past several centuries. It was the first comprehensive study combining data from many different archives of temperature including tree rings, ice cores, and coral reefs.

It demonstrated that Northern Hemisphere temperatures rose sharply during the late 20th century, in marked contrast to the relatively small temperature fluctuations during the previous six centuries. The graph got its name because its shape resembles a hockey stick, with the blade end representing the sharp temperature rise over recent years.

Listen to climate scientist Michael Mann talk about his early climate research on the Got Science? podcast:

As is typical of the scientific process, independent teams of researchers have worked to reproduce the results of the "hockey stick" by using their own approaches and even by using slightly different data. Despite small differences, they still yield the same essential conclusion: the past 10- to 20-year period was likely the warmest of the past millennium.

The hockey stick graph is a high-profile example among literally thousands of pieces of evidence that have contributed to the present scientific consensus on the human influence on global warming. We are observing real changes due to higher temperatures. Here are some examples from the AR5:

Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.

The rate of sea level rise since the mid-19th century has been larger than the rate during the previous two millennia.

Carbon dioxide concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.

Surface temperature is only one indicator of climate change.

Glaciers are melting. Sea levels and ocean heat content are rising (Figure 7). Patterns of rainfall and snow, droughts and storms, and lake and sea ice are changing. Plant and animal distributions and interactions are shifting and changing, with potential severe effects on crop pests and food supplies.

These shifts are well documented and are largely attributed to human-caused global warming, because scientists can positively identify the " human fingerprints " associated with these changing patterns.

Compared with natural factors that influence climate (including solar variation and volcanic eruptions), human activities - primarily burning fossil fuels and deforestation - have been a major contributor to climate change over the last 50 years. Burning coal, oil and gas and destroying forests overloads the atmosphere with excess carbon dioxide, adding to heat-trapping gases that already are present in the atmosphere. Combined, these gases act like a blanket covering the earth. The human contribution to this effect is unmistakable: the part of the atmosphere where excess carbon dioxide accumulates has expanded and warmed dramatically in recent years precisely during the period when emissions from human activity have increased.

The "Long" and "Short" of Temperature Trends

When one hears the words "global warming," the image that comes to mind is one of a globe where temperatures are going up constantly, like the water in a kettle on the burner of a stove that steadily rises in temperature. But when it comes to climate the process is not quite the same.

While global temperatures have been going up overall, the rate of warming varies. As a result, some years are warmer than others. That is because there are factors, like air and ocean circulation patterns, that affect both the rate and the intensity of the global warming. For example, every few years an ocean cycle appears in the Pacific ocean either as an El Niño and La Niña with global temperature and regional precipitation pattern changes.

Imagine that you add a few external factors to that imaginary warming kettle (a fan or air conditioning vent blowing directly at the stove; adding more water (hot or cold) to the kettle; a bucket of ice cubes sitting by its side; etc.) and what we have is a heating system that is affected by those other factors - but the water will still eventually boil unless the burner is turned off or turned down significantly.

The "burner" in global warming is represented by the heat-trapping emissions released to the atmosphere from the burning of coal, oil, and natural gas - and since that burner has not (yet!) been reduced significantly (enough for the heating to slow down and prevent boiling), what we have is a warming planet. Relatively short-term natural phenomena that cause global temperatures to fluctuate are also occurring throughout the seasons, which we experience as a result of the Earth's tilted axis as it revolves around the sun.

Short-term effects and external factors make it possible to have "cooler" periods in regions even as the general trend of warming continues. For example, during late 2007 and early 2008, the tropical Pacific Ocean was much cooler than normal due to a strong La Niña episode that kept temperatures across much of the globe lower than usual. Nevertheless, both years were still among the warmest years on record and would have been even hotter without this short-term cooling effect. Conversely, in 2015, a very strong El Niño episode, which made the tropical Pacific Ocean warmer than normal, combined with human-induced global warming to make that year the hottest on record to date (Nov 2016). And needless to say, winters continue to be colder than summers, even though some are more or less cold.

Oscillations between cooler and warmer periods are therefore expected, and do not change the long-term trend of warming shown by the data. Focusing on the relatively short time periods where the rate of warming is slower in order to claim that global warming is not happening is a misleading way to use statistics, yet one that has been the focus of attention. If one starts to measure a warming trend from a much warmer year, the rate of warming is bound to be different from the long term trend, simply due to the starting point (Figure 8).

Climate, Weather, and the United States

Climate is a good indicator of what to expect in general, such as cold days in February in New England. Weather, on the other hand, is what we actually experience, like a blustery, snowy day with temperatures in the low 20s. In other words, climate describes phenomena observed over long time periods, such as decades and centuries, while weather is observed over short time periods, such as days and weeks.

The Earth's average temperature is continuing to rise, regardless of the fact that some parts of the United States can still experience atypically cold winters (see this page for more on that). Cold winters do not disprove the fact that temperatures are rising. Plus, the US land area covers only about two percent of the Earth's surface, which means that even when much of the United States is cold, most of the rest of the world may be warmer.

Temperatures in the United States keep breaking records. In 2015 most of the country experienced temperatures above average or much above average, and unless global emissions are reduced significantly, the trend is likely to continue.

It's Not Too Late

The choices we make today can help determine what our climate will be like. Putting a limit on heat-trapping emissions and encouraging the use of healthier, cleaner energy technologies, such as solar and wind power, would help us to avoid the worst potential consequences of global warming.

# data[].attributes.attachment_link.title
Here's How we Know That the Earth's Temperature is Rising

# data[].attributes.attachment_link.description
In 2013, the Intergovernmental Panel on Climate Change (IPCC) concluded that "The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased". They also stated that "Human influence on the climate system is clear."

# data[].attributes.attachment_link.provider_name
Climate Change: Vital Signs of the Planet

# data[].attributes.attachment_link.readable_text
Our Trajectory

Earth Will Continue to Warm and the Effects Will Be Profound

The potential future effects of global climate change include more frequent wildfires, longer periods of drought in some regions, and an increase in the wind intensity and rainfall from tropical cyclones. Credit: left - Mike McMillan/USFS, center - Tomas Castelazo / Wikimedia Commons / CC BY-SA 4.0, right - NASA.

Global climate change is not a future problem. Changes to Earth's climate driven by increased human emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic ranges are shifting, and plants and trees are blooming sooner.

Effects that scientists had long predicted would result from global climate change are now occurring, such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves.

" The magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related losses and damages escalate with every increment of global warming."

- Intergovernmental Panel on Climate Change

Some changes (such as droughts, wildfires, and extreme rainfall) are happening faster than scientists previously assessed. In fact, according to the Intergovernmental Panel on Climate Change (IPCC) - the United Nations body established to assess the science related to climate change - modern humans have never before seen the observed changes in our global climate, and some of these changes are irreversible over the next hundreds to thousands of years.

Scientists have high confidence that global temperatures will continue to rise for many decades, mainly due to greenhouse gases produced by human activities.

A Degree of Difference

So, the Earth's average temperature has increased about 2 degrees Fahrenheit during the 20th century. What's the big deal?

Read more

The IPCC's Sixth Assessment report, published in 2021, found that human emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since 1850-1900. The global average temperature is expected to reach or exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth.

What's the difference between climate change and global warming?

"Global warming" refers to the long-term warming of the planet. "Climate change" encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.

detailed answer

The severity of effects caused by climate change will depend on the path of future human activities. More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. So, if we can reduce emissions, we may avoid some of the worst effects.

" The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss the brief, rapidly closing window to secure a liveable future." ²

- Intergovernmental Panel on Climate Change

Future Effects in the U.S.

U.S. Regional Effects

U.S. Regional Effects

Climate change is bringing different types of challenges to each region of the country. Some of the current and future impacts are summarized below. These findings are from the Third and Fourth National Climate Assessment Reports, released by the U.S. Global Change Research Program.

Is it too late to prevent climate change?

Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries.

detailed answer

Northeast. Heat waves, heavy downpours, and sea level rise pose increasing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries, and ecosystems will be increasingly compromised. Farmers can explore new crop options, but these adaptations are not cost- or risk-free. Moreover, adaptive capacity, which varies throughout the region, could be overwhelmed by a changing climate. Many states and cities are beginning to incorporate climate change into their planning.

Northwest. Changes in the timing of peak flows in rivers and streams are reducing water supplies and worsening competing demands for water. Sea level rise, erosion, flooding, risks to infrastructure, and increasing ocean acidity pose major threats. Increasing wildfire incidence and severity, heat waves, insect outbreaks, and tree diseases are causing widespread forest die-off.

Southeast. Sea level rise poses widespread and continuing threats to the region's economy and environment. Extreme heat will affect health, energy, agriculture, and more. Decreased water availability will have economic and environmental impacts.

Midwest. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Climate change will also worsen a range of risks to the Great Lakes.

Southwest. Climate change has caused increased heat, drought, and insect outbreaks. In turn, these changes have made wildfires more numerous and severe. The warming climate has also caused a decline in water supplies, reduced agricultural yields, and triggered heat-related health impacts in cities. In coastal areas, flooding and erosion are additional concerns.

References
References
Header image shows cracked mud stretches across sections of the Panamint Valley. Credit: NPS/Kurt Moses; A degree of concern thermometer image credit: Pixabay/geralt

# data[].attributes.attachment_link.keywords[]
intergovernmental panel on climate change

# data[].attributes.attachment_link.description
Vital Signs of the Planet: Global Climate Change and Global Warming. Long-term effects of global climate change in the United States.

# data[].attributes.body
Sea levels are too high

# data[].attributes.attachment_link.description
Our mission is to secure a safe and stable climate by accelerating the global transition to net-zero greenhouse gas emissions and a thriving, just, and resilient economy.

# data[].attributes.body
Climate change worsened the most destructive hurricanes of recent years, including Katrina, Irma and Maria, by intensifying rainfall by as much as 10%, new research has found.

'It's hyped up': climate change skeptics in the path of Hurricane Florence

High-resolution climate simulations of 15 tropical cyclones in the Atlantic, Pacific and Indian Oceans found that warming in the ocean and atmosphere increased rainfall by between 5% and 10%, although wind speeds remained largely unchanged

# data[].attributes.attachment_link.title
Climate change is making hurricanes even more destructive, research finds

# data[].attributes.attachment_link.description
Hurricane rainfall could increase by a third and wind speeds boosted by up to 25 knots if global warming continues

# data[].attributes.body
Drought

# data[].attributes.body
Roller coaster has flooded

# data[].attributes.body
Heatwaves

# data[].attributes.attachment_link.title
Is climate change making hurricanes worse?

# data[].attributes.attachment_link.description
The 2018 Atlantic hurricane season was expected to be 'below normal' but long-term trends paint a worrying picture

# data[].attributes.body
Hurricane from above

# data[].attributes.body
Stormy weather moving palm trees

# data[].attributes.body
April reached a new record Arctic low sea ice extent. Sea ice loss was rapid in the beginning of the month because of declines in the Sea of Okhotsk. The rate of ice loss slowed after early April, due in part to gains in extent in the Bering and Barents Seas. However, daily ice extent remained at record low levels throughout the month.

# data[].attributes.attachment_link.readable_text
As the long Arctic winter sets in, sea ice extent has increased at a faster than average pace. By the end of October, the ice cover had reached the Siberian coast, while open water persisted along the coasts of the Beaufort and Chukchi Seas. In the Antarctic, the spring decline in extent has been quite slow, but extent at the end of October remains at record low levels for this time of year.

Overview of conditions

Average Arctic sea ice extent for October 2023 was 6.37 million square kilometers (2.46 million square miles), seventh lowest in the 45-year satellite record (Figure 1a). Overall, during October sea ice extent increased by 119,800 thousand square kilometers (46,300 square miles) per day, which is faster than the 1981 to 2010 average of 89,200 square kilometers (34,400 square miles) per day (Figure 1b). The freeze up was particularly rapid along the Siberian Seas where the ice cover expanded to the coast by the end of the month. Open water remained in the Beaufort and Chukchi Seas at the end of October. Ice growth within the channels of the Canadian Archipelago closed off the Northwest Passage.

Conditions in context

Air temperatures over the Arctic Ocean at the 925 mb level (about 2,500 feet above the surface) were mostly above average during October, particularly in and around the Canadian Archipelago, which saw temperatures of 4 to 5 degrees Celsius (7 to 9 degrees Fahrenheit) above average (Figure 2a). Temperatures were modestly above average across the pole and over the Laptev and Kara Seas. The Chukchi and East Siberian Seas experienced near-average temperatures while temperatures were below average over the Bering Strait and the Barents and Norwegian Seas.

The atmospheric circulation featured weak high sea level pressure centered over the North Pole and fairly strong low pressure centered on the Norwegian Sea and north-central Siberia (Figure 2b). This pattern created strong winds along the Russian Arctic coast.

October 2023 compared to previous years

The downward linear trend in Arctic sea ice extent for October over the 45-year satellite record is 79,300 square kilometers (30,600 square miles) per year, or 9.5 percent per decade relative to the 1981 to 2010 average (Figure 3). Based on the linear trend, October has lost 3.49 million square kilometers (1.35 million square miles) of ice since 1979. This is equivalent to twice the size of Alaska.

Spring breaks slowly in the south

As the Antarctic heads toward summer following the record low maximum sea ice extent in September (winter), the rate of ice loss has been a bit slower than average. During October, the 2023 rate of decline was 29,100 square kilometers (11,200 square miles) per day, compared to the average rate of decline of 31,800 square kilometers (12,300 square miles) per day (Figure 4). The total decline in sea ice extent through October was 903,000 square kilometers (349,000 square miles), compared to the October average of 985,000 square kilometers (380,000 square miles).

Nonetheless, extent at the end of October remained at record low levels. The October 31, 2023, extent of 15.79 million square kilometers (6.10 million square miles) is 750,000 square kilometers (290,000 square miles) below the previous October 31 record low, which occurred in 1986. Extent is below average in the Ross Sea region and to the east of the Weddell Sea, as has been the case through most of austral winter. Extent is above average in the Amundsen and Bellingshausen Seas and near-average elsewhere.

# data[].attributes.attachment_link.description
As the long Arctic winter sets in, sea ice extent has increased at a faster than average pace. By the end of October, the ice cover had reached the Siberian coast, while open water persisted along the coasts of the Beaufort and Chukchi Seas.

# data[].attributes.body
Ice melting

# data[].attributes.body
Polar bear stuck from the result of the ice melting

# data[].attributes.body
As the growing season begins earlier and earlier, the risk of frost damage increases. And it is not clear what needs to be done to ensure that plants thrive through the entirety of the longer growing season.

# data[].attributes.attachment_link.readable_text
Scientists expect the global mean temperature to rise in the future.

One consequence is that by the end of this century, Norwegian farmers could be growing their crops for up to two months longer. In areas of higher elevation, in fact, the difference could turn out to be three months.

The growing season is defined as the number of days with an average temperature of at least 5°C.

Exploiting a warmer climate

A warmer climate would open up several exciting opportunities for Norwegian agriculture.

Thermophilic - warm-weather - crops could be cultivated farther north, and multiple harvests may be possible each summer, as is common at more southerly latitudes.

"Since the climate is likely becoming warmer, Norwegian farmers should take advantage of the new opportunities this entails," says Meteorologist Inger Hanssen-Bauer.

More tree diversity and more storage of CO2

The project describes a number of interesting developments that may occur if climate change continues on its present course.

Not only is a longer growing season for agriculture expected, but also more forest growth. The tree line will advance even further north, and Norway's most common tree species, the Norway spruce, will have to compete more with deciduous trees such as oak, beech and ash.

"This will allow forest managers to think along new lines," says Hanssen-Bauer.

More forest growth will also bind more CO2 - so the forests of Norway, Sweden and Finland could store even greater amounts of global carbon dioxide emissions.

But a warmer climate would also have some negative impacts for Norway's forests. For instance, insect pests such as ticks would range across larger swaths of the country, and several new wood-decaying fungi could be invading Norwegian forests.

Challenges for farmers

Agriculture would also face some major challenges. As the growing season begins earlier and earlier, the risk of frost damage increases. And it is not clear what needs to be done to ensure that plants thrive through the entirety of the longer growing season.

"A warmer climate means the growing season extends longer into the autumn," Bauer-Hanssen points out.

"But near the end of the season, the weak daylight here in the north would be a limiting factor. Plants stop growing without enough light, even if the climate is warm."

# data[].attributes.attachment_link.title
Climate change can lengthen growing season

# data[].attributes.attachment_link.description
Scientists expect the global mean temperature to rise in the future. One consequence is that by the end of this century, Norwegian farmers could be growing their crops for up to two months longer. In areas of higher elevation, in fact, the difference could turn out to be three months.

# data[].attributes.body
Growing Season

# data[].attributes.body
Extra crops to harvest

# data[].attributes.body
Rising sea levels can destroy coastal town such as Raglan, Kiakoura, New Plymouth and Bluff.

# data[].attributes.body
Droughts can effect the animals from getting fresh water effecting their health. Plants and crops wont grow effecting farmers.

# data[].attributes.body
Rising sea levels can destroy coastal town such as Raglan, Kiakoura, New Plymouth and Bluff.

# data[].attributes.body
Rising sea levels can destroy coastal town such as Raglan, Kiakoura, New Plymouth and Bluff.

# data[].attributes.body
Rising sea levels can destroy coastal town such as Raglan, Kiakoura, New Plymouth and Bluff.

# data[].attributes.body
Farmers will have an increase in crops, bringing more money but the price for the product will decrease lessening the value.