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24. How does tree ring growth or lack of growth support or refute climate changes in the last 100 years? 

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24. How does tree ring growth or lack of growth support or refute climate changes in the last 100 years? 

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Tree rings are sensitive to climate conditions. "tree rings usually grow wider in warm, wet years and they are thinner in years when it is cold and dry. If the tree has experienced stressful conditions, such as a drought, the tree might hardly grow at all in those years" Since many trees are much older than 100 years, scientists can compare recent growth years to years from the past to either. Lack of growth supports the argument that our climate is changing for the worse.

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Quite a lot, actually!

But to understand what the trees tell us, we first have to understand the difference between weather and climate.

is a specific event-like a rain storm or hot day-that happens over a short period of time. Weather can be tracked within hours or days. is the average weather conditions in a place over a long period of time (30 years or more).

Scientists at the National Weather Service have been keeping track of weather in the United States since 1891. But trees can keep a much longer record of Earth's climate. In fact, trees can live for hundreds-and sometimes even thousands-of years!

One way that scientists use trees to learn about past climate is by studying a tree's rings. If you've ever seen a tree stump, you probably noticed that the top of the stump had a series of rings. It looks a bit like a bullseye.

These rings can tell us how old the tree is, and what the weather was like during each year of the tree's life. The light-colored rings represent wood that grew in the spring and early summer, while the dark rings represent wood that grew in the late summer and fall. One light ring plus one dark ring equals one year of the tree's life.

Because trees are sensitive to local climate conditions, such as rain and temperature, they give scientists some information about that area's local climate in the past. For example, tree rings usually grow wider in warm, wet years and they are thinner in years when it is cold and dry. If the tree has experienced stressful conditions, such as a drought, the tree might hardly grow at all in those years.

Scientists can compare modern trees with local measurements of temperature and precipitation from the nearest weather station. However, very old trees can offer clues about what the climate was like long before measurements were recorded.

In most places, daily weather records have only been kept for the past 100 to 150 years. So, to learn about the climate hundreds to thousands of years ago, scientists need to use other sources, such as trees, corals, and ice cores (layers of ice drilled out of a glacier).

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What Can Trees Tell Us About Climate Change?

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Tree rings can provide information about past climate!

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23. Droughts and forest fires are on the rise all around the world. If there is no water for the plants to drink and survive, how can they effectively remove carbon dioxide from the atmosphere? 

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23. Droughts and forest fires are on the rise all around the world. If there is no water for the plants to drink and survive, how can they effectively remove carbon dioxide from the atmosphere? 

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Since photosynthesis requires H2O, plants will not be able to effectively remove CO2 from the earth with out water. There are oceanic plants that will be okay so humans will not completely run out of oxygen but the ratio of oxygen to CO2 will be worse.

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22. Carbon Dioxide has been accociated with the warming of Earth. You have learned in Biology class that co2 in the atmosphere is taken out of the air by plants and trees through photosynthesis and replaced with breathable oxygen.          a. does this statement support global warming deniers? Explain.                                       b. Does this statement support climate science research? Explain.                                       c. Does your answer change when you consider deforestation and increased demand for paper and housing? 

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22. Carbon Dioxide has been accociated with the warming of Earth. You have learned in Biology class that co2 in the atmosphere is taken out of the air by plants and trees through photosynthesis and replaced with breathable oxygen.          a. does this statement support global warming deniers? Explain.                                       b. Does this statement support climate science research? Explain.                                       c. Does your answer change when you consider deforestation and increased demand for paper and housing? 

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a. yes. CO2 traps heat radiation in the earth and plants not being able to convert CO2 to O2 contributes to global warming.
b. Yes. refer to question 23 and then question 18.
c. No. The less trees we have the worse our CO2 levels will get. The more CO2 the more heat that is trapped.

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21. Think of Goldilocks and the three bears again. How would you characterize the weather patterns of the US in the last decade from 2008-2018? Very severe weather patters, very weak weather patterns, or consistently average weather patterns. Consider hurricanes, tornadoes, thunderstorms, flooding events, droughts. support with evidence. 

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21. Think of Goldilocks and the three bears again. How would you characterize the weather patterns of the US in the last decade from 2008-2018? Very severe weather patters, very weak weather patterns, or consistently average weather patterns. Consider hurricanes, tornadoes, thunderstorms, flooding events, droughts. support with evidence. 

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I would consider it severe weather patterns. There seem to be more and more hurricanes, tornadoes, thunderstorms, flooding and droughts happening more and more often.

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20. How do El Nino weather patterns influence climate? 

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20. How do El Nino weather patterns influence climate? 

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El Nino weather patterns happen when the index hit 0.5 degrees Celsius warmer or more. In an El Nino weather pattern it is typically
*Wetter in the southern US and East coast.
*Drier in the Ohio Valley, Great Lakes, Northwest and Northern Rockies.
*Cooler Desert Southwest, Southern Plains, Northern Gulf Coast
*Warmer in the Northern tier of states from the Pacific Northwest to the Northern Plains, Great Lakes, and Northeast.

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19. Clouds (water vapor) are considered a greenhouse gas. How can cloud coverage both complicate the heating of Earth and also help alleviate the heating of Earth? 

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19. Clouds (water vapor) are considered a greenhouse gas. How can cloud coverage both complicate the heating of Earth and also help alleviate the heating of Earth? 

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When clouds are covering an area, it traps the heat so the earth becomes hotter. But when clouds are not covering an area, the heat escapes making the temperature decrease.  We see this happen often in the winter.

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18. How does carbon dioxide trap infrared radiation on Earth?

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18. How does carbon dioxide trap infrared radiation on Earth?

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Carbon Dioxide is a greenhouse gas.

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17. Why is there less heat escaping into space? 

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17. Why is there less heat escaping into space? 

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16. What are seas surface temperatures (SST)? Think of Goldilocks and the Three Bear... are SSTs too hot, too cold or just right? explain. 

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16. What are seas surface temperatures (SST)? Think of Goldilocks and the Three Bear... are SSTs too hot, too cold or just right? explain. 

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SSTs are measured five meters below the sea surface. A mooring buoy captures the temperature. SSTs need to be just right so ocean storms do not happen.

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A major accomplishment in the distribution of satellite derived SSTs occurred with the Group for High Resolution Sea Surface Temperature (GHRSST) project. The project provides all SST data sets in a common format that allows for easy accessibility across different computer platforms and operating systems. To provide data sets that are suitable for climate modeling a necessary requirement is that climate data records come with a description of the errors associated with each SST value.

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15. What is ocean acidification? How has this influenced our oceans over the last 100 years ?

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15. What is ocean acidification? How has this influenced our oceans over the last 100 years ?

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Ocean acidification is when carbonic acid is formed in the ocean- this is bad. Ocean acidification has been shown to reduce the ability to allow coral reef to be built.

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US Department of Commerce, National Oceanic and Atmospheric Administration

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Ocean acidification refers to a reduction in the pH of the ocean over an extended period time, caused primarily by uptake of carbon dioxide (CO2) from the atmosphere.

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14. If the glaciers melt, where does most of that liquid (freshwater) go? (Is ocean water drinkable?) Can ocean water be used to irrigate crops for 7 billion Earthlings? 

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14. If the glaciers melt, where does most of that liquid (freshwater) go? (Is ocean water drinkable?) Can ocean water be used to irrigate crops for 7 billion Earthlings? 

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Most of the melted glaciers falls into the ocean. Ocean water has to be filtered a ton in order to be drinkable. Since ocean water has salt, it is not good to irrigate massive amounts of crops with it.

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Boats and boating--Equipment and supplies

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Desalination: Drink a cup of seawater? - US Geological Survey

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What do we mean by "saline water?" Water that is saline contains significant amounts (referred to as "concentrations") of dissolved salts. In this case, the concentration is the amount (by weight) of salt in water, as expressed in "parts per million" (ppm).

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13. How have sea levels fluctuated over the last several thousand years? Is this driven by natural circumstances or is this caused by human influence. In your opinion, why? 

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13. How have sea levels fluctuated over the last several thousand years? Is this driven by natural circumstances or is this caused by human influence. In your opinion, why? 

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The sea level has been increasing over the last thousand years. Scientists believe that this is caused by human influence "Sea level started rising in the late 1800s, soon after we started burning coal, gas and other fossil fuels for energy."

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12. What can ice cores tell us about the history of Earth's climate over time? How far back in time can ice cores provide information? 

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12. What can ice cores tell us about the history of Earth's climate over time? How far back in time can ice cores provide information? 

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Ice cores can tell us about:
* past air temperatures
*Past greenhouse gasses
*Other gasses
*melt layers
* accumulation rate

The ice cores can date back about 10,000 years

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1. Jouzel, J. and V. Masson-Delmotte, 2010. Deep ice cores: the need for going back in time. Quaternary Science Reviews, 29(27): 3683-3689.

2. Augustin, L., C. Barbante, P.R.F. Barnes, J.M. Barnola, M. Bigler, E. Castellano, O. Cattani, J. Chappellaz, D. DahlJensen, B. Delmonte, G. Dreyfus, G. Durand, S. Falourd, H. Fischer, J. Fluckiger, M.E. Hansson, P. Huybrechts, R. Jugie, S.J. Johnsen, J. Jouzel, P. Kaufmann, J. Kipfstuhl, F. Lambert, V.Y. Lipenkov, G.V.C. Littot, A. Longinelli, R. Lorrain, V. Maggi, V. Masson-Delmotte, H. Miller, R. Mulvaney, J. Oerlemans, H. Oerter, G. Orombelli, F. Parrenin, D.A. Peel, J.R. Petit, D. Raynaud, C. Ritz, U. Ruth, J. Schwander, U. Siegenthaler, R. Souchez, B. Stauffer, J.P. Steffensen, B. Stenni, T.F. Stocker, I.E. Tabacco, R. Udisti, R.S.W. van de Wal, M. van den Broeke, J. Weiss, F. Wilhelms, J.G. Winther, E.W. Wolff, M. Zucchelli, and E.C. Members, 2004. Eight glacial cycles from an Antarctic ice core. Nature, 429(6992): 623-628.

3. Johnsen, S.J., D. Dahl-Jensen, N. Gundestrup, J.P. Steffensen, H.B. Clausen, H. Miller, V. Masson-Delmotte, A.E. Sveinbjornsdottir, and J. White, 2001. Oxygen isotope and palaeotemperature records from six Greenland ice-core stations: Camp Century, Dye-3, GRIP, GISP2, Renland, and NorthGRIP. Journal of Quaternary Science, 16: 299-307.

4. Mulvaney, R., N.J. Abram, R.C.A. Hindmarsh, C. Arrowsmith, L. Fleet, J. Triest, L.C. Sime, O. Alemany, and S. Foord, 2012. Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history. Nature, 489: 141-144.

5. Lambert, F., B. Delmonte, J.-R. Petit, M. Bigler, P.R. Kaufmann, M.A. Hutterli, T.F. Stocker, U. Ruth, J.r.P. Steffensen, and V. Maggi, 2008. Dust-climate couplings over the past 800,000 years from the EPICA Dome C ice core. Nature, 452(7187): 616-619.

6. Brook, E.J., ICE CORE METHODS | Overview, in Encyclopedia of Quaternary Science, A.E. Scott, Editor. 2007, Elsevier: Oxford. 1145-1156.

7. Aciego, S., B. Bourdon, J. Schwander, H. Baur, and A. Forieri, 2011. Toward a radiometric ice clock: uranium ages of the Dome C ice core. Quaternary Science Reviews, 30(19): 2389-2397.

8. Abram, N.J., R. Mulvaney, E.W. Wolff, J. Triest, S. Kipfstuhl, L.D. Trusel, F. Vimeux, L. Fleet, and C. Arrowsmith, 2013. Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century. Nature Geosci, advance online publication.

9. Jouzel, J. and V. Masson-Delmotte, ICE CORE RECORDS | Antarctic Stable Isotopes, in Encyclopedia of Quaternary Science, A.E. Scott, Editor. 2007, Elsevier: Oxford. 1242-1250.

10. Bertler, N.A.N., P.A. Mayewski, and L. Carter, 2011. Cold conditions in Antarctica during the Little Ice Age - implications for abrupt climate change mechanisms. Earth and Planetary Science Letters, 308: 41-51.

11. Grachev, A.M., ICE CORE RECORDS | Thermal Diffusion Paleotemperature Records, in Encyclopedia of Quaternary Science, A.E. Scott, Editor. 2007, Elsevier: Oxford. 1280-1284.

12. Abbott, P.M. and S.M. Davies, 2012. Volcanism and the Greenland ice-cores: the tephra record. Earth-Science Reviews, 115(3): 173-191.

13. Hoek, W., Z. Yu, and J.J. Lowe, 2008. INTegration of Ice-core, MArine, and TErrestrial records (INTIMATE): refining the record of the Last Glacial - Interglacial Transition. Quaternary Science Reviews, 27(1): 1-5.

14. Abram, N.J., E.W. Wolff, and M.A.J. Curran, 2013. A review of sea ice proxy information from polar ice cores. Quaternary Science Reviews, 79(0): 168-183.

15. Fischer, H., F. Fundel, U. Ruth, B. Twarloh, A. Wegner, R. Udisti, S. Becagli, E. Castellano, A. Morganti, and M. Severi, 2007. Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica. Earth and Planetary Science Letters, 260(1): 340-354.

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1. Jouzel, J. and V. Masson-Delmotte, 2010. Deep ice cores: the need for going back in time. Quaternary Science Reviews, 29(27): 3683-3689. 2. Augustin, L., C. Barbante, P.R.F. Barnes, J.M. Barnola, M. Bigler, E. Castellano, O. Cattani, J. Chappellaz, D. DahlJensen, B. Delmonte, G. Dreyfus, G. Durand, S. Falourd, H.

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11. Find a graphic of human-influenced carbon dioxide emissions and the atmospheric concentration of carbon dioxide. Do the graphs you found look like hockey sticks? explain. 

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11. Find a graphic of human-influenced carbon dioxide emissions and the atmospheric concentration of carbon dioxide. Do the graphs you found look like hockey sticks? explain. 

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The graphs look like hockey sticks. This is because up until 1900ish very little emissions was released into the atmosphere (hense the flat part). Once 1900ish hit, we started emitting more and more into the atmosphere and the carbon levels skyrocketed with the emissions levels (hense the stick)

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10. How does an increasing consumption of and demand for fish in a human's diet relate to carbon emissions? 

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10. How does an increasing consumption of and demand for fish in a human's diet relate to carbon emissions? 

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Smaller fish that consume oceanic plants have the smallest carbon footprint. But fish that consumer other fish have a higher carbon footprint. Regardless of what we eat our diet will have a carbon footprint.

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Food is expensive. Not just for pocketbooks, but for the planet. Worldwide, more than 25 percent of greenhouse gas emissions come from food production. That's methane belched from cows and nitrous oxide escaping from soils, as well as fossil fuels burned by tractors, fishing boats and rumbling transport vehicles. Some foods cost more than others.

Seafood has a smaller carbon footprint than other animal proteins, on average, because fishing doesn't require farmland or care of livestock. But even among seafoods, fish and shellfish can have varying impacts.

So what's the best choice? Small schooling species, like anchovies and herring, are the most sustainable options, experts say, based on energy use and emissions of their fisheries. There's no free lunch. The question is, what can the planet afford?

Small schooling fish are low impact because catching them doesn't burn much fossil fuel, the major source of emissions for fisheries.

Ninety percent of the greenhouse gas emissions associated with wild seafood come from fuel use, said Peter Tyedmers, who studies the environmental consequences of food systems at Dalhousie University in Halifax, Nova Scotia.

"If you think about fishing, where does fuel get burned?" he said. "On a fishing boat, it's driving the engine. Some fisheries guzzle more gas than others. It depends how long and how hard the engine works.

Fisheries targeting anchovy, mackerel and similar fish are the most fuel efficient, according to a 2015 study coauthored by Tyedmers. They average less than 80 liters of fuel per ton of catch when fishermen use purse-like nets to surround huge schools of the fish. Because these species swim in dense aggregations, fishermen can locate a swarm, throw a net around the whole thing, and pull up thousands of fish in one trip.

Compare this to crustaceans like Australian Tiger prawns or Norway lobster, which can burn more than 10,000 liters of fuel per ton of catch. That's because it takes a lot of gas to drag a heavy prawn net through the water, as does motoring from one lobster trap to another. Scooping up a whole school of fish at once is much more fuel efficient.

Conservation status matters too, said Nathan Pelletier, an ecological economist and industrial ecologist, specializing in food system sustainability at the University of British Columbia. When populations are healthy, there are more fish in the water, so it takes less time and less fuel to fill a net. Overfishing leaves fewer fish out there, so it takes more time and energy to catch the same amount.

"Abundant fisheries, from a climate change perspective, will be less greenhouse gas intensive," Pelletier said. "All else being equal, the more fish there are, the less energy we will have to invest in chasing them around and catching them."

Farmed mollusks may be another climate-conscious seafood, according to a forthcoming study by ecologist Ray Hilborn, at the University of Washington in Seattle. That's because these shellfish don't need to be fed; they can filter sustenance from the water instead. Animal feed can be a huge consideration when it comes to a farm's carbon footprint.

"From a climate change perspective, what you feed and how much you feed matters a lot," said Tyedmers. "In aquaculture, the big generalization is your greenhouse gas emissions are overwhelmingly driven by your feed inputs."

Farmed fish eat a combination of plant and animal parts, like ground up soy or corn, chicken feathers, animal bones and blood. Each ingredient takes energy to grow or catch, and then more energy to process into pellets or flakes. Farming mollusks sidesteps that issue, because they're filter-feeders, no pellets required.

Hold on though, Pelletier said. The jury is still out on mollusks. They don't need to be fed, but they do take effort to seed, harvest and process for human consumption. Considering the amount of meat on a mussel or oyster, it's a low edible yield for the effort.

Farmed mollusks may look good in theory, but Pelletier says he'd be cautious to endorse them, because "it's mostly shell."

Of course, to reduce carbon footprints as much as possible, the best bet is to eat veggies. On average, eating plants has a smaller footprint than eating animals, said Friederike Ziegler, who studies sustainable seafood at the Research Institutes of Sweden, in Gothenburg. But among animal products, seafoods are some of the best, she said. And among seafoods, little fish are the best of the best.

In Sweden, where Ziegler lives and works, the government recommends eating seafood two to three times per week. Most Swedes eat less than that. Small, schooling fish like herring are famously popular in Scandinavia, but even in Sweden, Ziegler said people could eat more fish.

Not everyone can switch to veggies, for both cultural and nutritional reasons. Wild sustainable seafood is the best option, in many parts of the world. When it comes to changing diets, "we have to think about solutions that are culturally appropriate and feasible within their specific contexts," Pelletier said.

Climate change looms large over the future. To fight it, think like an ocean predator. Dive into the little fish, with big potential for good.

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Eating seafood can reduce your carbon footprint, but some fish are better than others

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Food is expensive. Not just for pocketbooks, but for the planet. Worldwide, more than 25 percent of greenhouse gas emissions come from food production. That's methane belched from cows and nitrous oxide escaping from soils, as well as fossil fuels burned by tractors, fishing boats and rumbling transport vehicles.

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9. How does an increasing consumption of and demand for meat in a human's diet relate to carbon emissions? 

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9. How does an increasing consumption of and demand for meat in a human's diet relate to carbon emissions? 

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Meats have the highest carbon footprint of all food. "Food’s carbon footprint, or foodprint, is the greenhouse gas emissions produced by growing, rearing, farming, processing, transporting, storing, cooking and disposing of the food you eat."

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Food's carbon footprint, or foodprint, is the greenhouse gas emissions produced by growing, rearing, farming, processing, transporting, storing, cooking and disposing of the food you eat.

In the US, each household produces 48 tons of greenhouse gases. Transport, housing and food have the three largest carbon footprints. Food produces about 8 tons of emissions per household, or about 17% of the total. Worldwide, new reports suggest that livestock agriculture produces around a half of all man-made emissions.

Changing the foods that you eat can have a big impact on your carbon footprint. And reduce pollution, preserve the environment and slow global warming. Many of these changes will also save you money, improve your health and even keep you fit! Have a browse of How You Can Fight Climate Change for more ideas on taking action to save our beautiful planet.

Carbon Footprint Ranking of Food

The following table shows the greenhouse gas emissions produced by one kilo of each food. It includes all the emissions produced on the farm, in the factory, on the road, in the shop and in your home. It also shows how many miles you need to drive to produce that many greenhouse gases. For example, you need to drive 63 miles to produce the same emissions as eating one kilogram of beef.

Meat, cheese and eggs have the highest carbon footprint. Fruit, vegetables, beans and nuts have much lower carbon footprints. If you move towards a mainly vegetarian diet, you can have a large impact on your personal carbon footprint.

Figures from the Environmental Working Group's Meat Eater's Guide and the EPA's Guide to Passenger Vehicle Emissions.

Top Tips for Reducing your Carbon Footprint

1. Food's Carbon Footprint: Eat vegetarian

Livestock farming produces from 20% to 50% of all man-made greenhouse gas emissions.

Shrink That Footprint 's chart shows that a meat lover has the highest carbon footprint at 3.3 tons of greenhouse gas emissions. A vegan diet has the lowest carbon footprint at just 1.5 tons CO2e (Carbon Dioxide Equivalent). You can reduce your foodprint by a quarter just by cutting down on red meats such as beef and lamb.
The carbon footprint of a vegetarian diet is about half that of a meat-lover's diet.
It's good for the animals too! Most animals are raised in factory farms where they live in horrific conditions. The factory workers also suffer from poor wages and dangerous working practices. Factory farms are heavy polluters of the air and ground. The meat they produce is also polluted with superbugs. Over 3.5 million people get sick from eating 'dirty' meat every year in the US.

It's good for you too! Vegetarians live longer than meat-eaters. Vegetarians are slimmer than meat-eaters. Vegetarians have a lower risk of getting heart disease, high blood pressure, diabetes and cancer.

Browse Healthy Eating for more tips on a healthy, vegetarian diet.

use proteins such as beans, lentils, tofu, tempeh and quorn to replace meat, cheese and eggs

make sure you are getting enough iron and zinc by including lots of wholegrains, beans and a variety of vegetables

invest in some vegetarian or vegan cookery books and have fun experimenting

don't rely on vegetarian processed foods.

Green Fact: 70% of the deforestation of the Amazon is to provide land for cattle ranches.

2. Food's Carbon Footprint: Bring back home-cooking

Take control of the food you eat and base your meals on natural foods such as vegetables, fruits, whole-grains, beans and lentils with a little meat and fish:

discover the simple pleasures of preparing and eating your own meals

check out Vegetarian Recipes for lots of tasty ideas

improve the health of you and your family - see more at Vegetarian Nutrition

plan your meals ahead to reduce wastage

save your leftovers and create a new meal with them

if you can, make your own compost with uncooked vegetable scraps.

Check out Why Food Waste is a Good Thing! for more tips on how to reduce food wastage.

Green Fact: British and American households throw out a THIRD of the food that they buy!

3. Food's Carbon Footprint: Cooking smartly

Did you know that a gas oven only uses 6% of its energy to cook? And an electric oven is not much better at 12%. If you use the oven on a warm day, you will also heat up the room and need to turn on a fan or air-conditioning. In fact, the most efficient cooking method is simmering on the stove-top.

eat more raw foods that do not need cooking

use the stove-top whenever possible

next best is the microwave as it uses 50% less energy than an oven

use the oven sparingly and smartly...reduce preheating, cook multiple foods, turn off early

use electric kettles to boil water for cooking or drinking.

4. Food's Carbon Footprint: Eat Organic

Organic farming methods for both crops and animals have a much lower impact on the environment than conventional methods. Organic-certified farms must use natural methods for soil fertilisation, weed prevention and pest control. Antibiotics and growth hormones cannot be used to raise food animals, and there are standards of care which prevent cruelty to livestock. Genetically-modified and irradiated foods cannot be labelled organic and its better to avoid these processes which are not proven to be safe for us or the food chain.

Organic food is better for you too! Crops are grown in fertile soils that are full of nutrients - and these end up in your food and then in you. Livestock are able to roam the fields and eat their natural food - grass - rather than being force-fed corn. And this leads to a much less fatty meat that keeps your heart healthier.

Find out which fruits and vegetables are the worst and least contaminated with pesticides at Eat Organic, Drink Clean.

Green Fact: poor soil management costs the US $10 billion every year in lowered yields and lost nutrients.

5. Food's Carbon Footprint: Save water

Water is a precious resource that is becoming scarce in many countries such as Egypt, Mexico, Pakistan and Australia. And even if you do not live in one of these arid countries, you may be wearing or using goods and consuming foods produced in those places, thus contributing to their water debt. One of the major impacts we can have personally is by moving towards a vegetarian diet, which requires about half the water to produce than a meat-based diet. It also makes sense to reduce your personal water consumption by practicing water conservation in your daily life:

eat a mainly vegetarian diet

only use the dishwasher when full and select the program with low water usage

if you wash-up by hand, start with a half-empty bowl and rinse the dishes back into your washing-up water rather than down the plughole

use filtered tap water for drinking rather than energy and water-intensive bottled water

take a shower rather than a bath and shower less often in less time!

turn off the taps when brushing your teeth or washing or shaving

clean your clothes less often and only wash full loads

use 'grey' water to water your garden and house-plants.

Green Fact: the average Australian uses around 30,000 gallons of water per year around the home for drinking, washing, cooking, laundry etc but it takes around 400,000 gallons of water to produce the crops that feed and clothe them!

6. Food's Carbon Footprint: Shop wisely

Think before you buy! Do you actually need this? Can you find a better, greener alternative?

use a shopping list to avoid those impulse purchases

avoid products that use lots of packaging

buy in bulk to save money and reduce packaging

check the label - a long list of ingredients generally means a heavily processed item with a high carbon footprint

frozen food has the highest carbon footprint, followed by canned, plastic, glass, then cardboard

and please don't buy bottled water.

Green Fact: around 5,000 million pounds weight of plastic water bottles were produced in 2005 and only 20% were recycled. That's a lot of waste in our landfills, on our streets and in our oceans.

7. Food's Carbon Footprint: Shop local

Think about where you do your shopping. Do you drive to the local shop when you need something - why not walk? Does your supermarket support green initiativesand offer local, organic foods? Is there a nearby farmer's market or co-op you can use? And think about where food comes from - if it is from the other side of the world, it will have a high transportation footprint.

A weekly food shop is a habit many of us follow...but is it an efficient use of time and resources? The average household throws away a third of the food that they buy as it is so easy to over-shop in those tempting supermarkets. After all, they are designed to sell us as much as possible, whether we need it or not. What about shopping in bulk every other week for non-perishable goods, and using your local shops for fresh foods?

Green fact - around 11% of the greenhouse emissions involved in food production are linked to food transportation.

8. Food's Carbon Footprint: Reuse and recycle

Think creatively about how you can reuse and recycle. Glass jars and plastic containers make great storage options. Take your own shopping bags and say no to plastic bags. Take reusable produce bags for your fruit and vegetables - if you use the ethylene-absorbing bags it prolongs shelf-life too. And when you can't reuse, make sure you recycle whatever you can.

9. Food's Carbon Footprint: Grow your own food

A great way to save money, get fit and reduce your carbon footprint is to grow your own fruit and vegetables. If you have a garden or backyard, then it is a fun way to make sure your family has access to affordable, healthy, pesticide-free food. And even if you live in an apartment, what about using your balcony or even the communal outside areas? Failing that, there is a growing movement (ha!) in Australia and The States to set up community gardens.

Food's Carbon Footprint - how to reduce your carbon footprint by eating healthily.

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Food's carbon footprint, or foodprint, is the greenhouse gas emissions produced by growing, rearing, farming, processing, transporting, storing, cooking and disposing of the food you eat. In the US, each household produces 48 tons of greenhouse gases. Transport, housing and food have the three largest carbon footprints.

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8. Does gasoline that most cars need to operate and function contribute to the Earth's greenhouse effect? 

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8. Does gasoline that most cars need to operate and function contribute to the Earth's greenhouse effect? 

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The gasoline that burns from cars contributes to the greenhouse gas effect. (car emissions = bad)

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On the Green Vehicle Guide (GVG), a higher CO 2 number means the car produces higher levels of carbon dioxide (CO 2) from the tailpipe. All new vehicle models up to 3.5 tonnes gross vehicle mass sold in Australia are tested to determine both fuel consumption and the level of CO 2 emissions emitted.

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1. Why do people believe global warming is occurring on Earth? 

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1. Why do people believe global warming is occurring on Earth? 

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People believe in Global Warming because of these elements of scientific evidence:
*Global Temperature Rise
*Warming Oceans
*Shrinking Ice Sheets
*Glacial Retreat
*Decreased Snow Cover
*Sea Level Rise
*Declining Arctic Sea Ice
*Extreme events
*Ocean Acidification

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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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3. Where is the fastest warming of Earth's atmosphere occurring? 

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3. Where is the fastest warming of Earth's atmosphere occurring? 

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The northern hemisphere. Russia, Alaska, North Pole, Greenland area.

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climate change, global climate change, global warming, natural hazards, Earth, environment, remote sensing, atmosphere, land processes, oceans, volcanoes, land cover, Earth science data, NASA, environmental processes, Blue Marble, global maps

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5. Are increasing levels of carbon dioxide in the atmosphere safe for human existence? 

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5. Are increasing levels of carbon dioxide in the atmosphere safe for human existence? 

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A very high concentration of CO2 can kill us. CO2 is not the best for our health as too much in the area can cause drowsiness, dizziness, confusion, headache, shortness of breath, reduced hearing, muscular tremor, increased heart rate and blood pressure, and excessive sweating. But plants need CO2 so we can in return grow more food.

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Carbon dioxide is a gas consisting of one part carbon and two parts oxygen. It is one of the most important gases on the earth because plants use it to produce carbohydrates in a process called photosynthesis. Since humans and animals depend on plants for food, photosynthesis is necessary for the survival of life on earth.

However, CO2 can also have negative effects. As CO2 builds up in our atmosphere it has a warming effect that could change the earth's climate. Indoors, CO2 levels easily rise above the recommended amount which has adverse effects.

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Carbon Dioxide - What is it and how does it impact your health

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Carbon dioxide is a gas consisting of one part carbon and two parts oxygen. It is one of the most important gases on the earth because plants use it to produce carbohydrates in a process called photosynthesis. Since humans and animals depend on plants for food, photosynthesis is necessary for the survival of life on earth.

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6. What's an environmental refugee? What places will people flee from? Where will they go? 

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6. What's an environmental refugee? What places will people flee from? Where will they go? 

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environmental refugee- people that were forced to flee from their homes due to sudden or gradual alterations in the natural environment related to sea-level rise, extreme weather events and drought and water scarcity. An area that will be evacuated soon is the Maldives because of the rise in sea level. These people will probably flee inland or to higher elevation to avoid another evacuation from their new homes that they have to build.

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Climate

Extreme weather events - from floods and storms, to heatwaves and drought - are already displacing an estimated 41 people each minute, and as temperatures continue to increase, climate extremes will worsen, sea levels will rise, and the world's most vulnerable will bear the brunt.

Sign our petition to protect climate refugees

Giving vulnerable communities a voice

Climate change is a human rights issue, and EJF is working tirelessly to give these vulnerable communities a voice and secure international protection for climate refugees.

EJF calls on all countries to rapidly and fully implement the global climate agreement agreed in Paris in December 2015 and support efforts to raise their emission reduction pledges over time in line with its goal to phase out man-made emissions and keep global temperature rise below 1.5°C on pre-industrial levels.

EJF calls on governments to recognise climate refugees and support a new legal agreement to guarantee their rights and their fair claim to our shared world. These populations currently have no support under existing legislation, such as the 1951 Geneva Convention to protect those fleeing war and persecution.

EJF calls for a UN Special Rapporteur on Human Rights and Climate Change to examine the issues surrounding climate change and human mobility, help protect the most disadvantaged and vulnerable populations within and across countries, and guide international action on climate-induced displacement.

"Climate change [is] now found to be the key factor accelerating all other drivers of forced displacement. These persons are not truly migrants, in the sense that they did not move voluntarily. As forcibly displaced not covered by the refugee protection regime, they find themselves in a legal void."
UN Secretary-General, António Guterres

Sign up to our mailings to stay up to date with our climate campaign

What is a climate refugee?

EJF defines a climate refugee as "persons or groups of persons who, for reasons of sudden or progressive climate-related change in the environment that adversely affects their lives or living conditions, are obliged to leave their habitual homes either temporarily or permanently, and who move either within their country or abroad"

A global rise in climate refugees

From investigations into climate displacement in rural Bangladesh, to collaborations with local journalists in Kenya's Dadaab Refugee Camp, EJF has been able to document the stories of climate witnesses, and bring their stories to government officials of the highest levels.

Our films Land of Rivers, and No Place Like Home: Rising Waters - shown in cinemas across the UK - have also helped to increase public awareness for the plight of those forced to flee their homes because of climate change.

Since EJF began working to raise awareness of the plight of climate refugees, we have seen the issue garner international recognition. A decade ago, the concept was relatively unheard of or ignored on the global stage. Now, however, the term is widely used by governments, UN bodies and media across the world.

Yet, between 2008 and 2016, 21.5 million people were displaced by climate related disasters - more than those fleeing war or persecution - as extreme weather events continued to claim lives and livelihoods across the globe.

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Protecting climate refugees | Environmental Justice Foundation

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Climate Extreme weather events - from floods and storms, to heatwaves and drought - are already displacing an estimated 41 people each minute, and as temperatures continue to increase, climate extremes will worsen, sea levels will rise, and the world's most vulnerable will bear the brunt.

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7. Let's say after college you return to Lisle permanently for the rest of your life. We live in close proximity to the Great Lakes. In 50 years, would we be fleeing our area or accepting environmental refugees into our area? Explain. 

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7. Let's say after college you return to Lisle permanently for the rest of your life. We live in close proximity to the Great Lakes. In 50 years, would we be fleeing our area or accepting environmental refugees into our area? Explain. 

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Chicagoland will be fine. Compared to the other two gigantic cities on the coast. They believe that Chicago and the mid-west is the safe-haven that people from both coasts will flee towards. As for chicago, they have this giant tunnel that is build to hold lots of water which can help manage any flooding that does occur.

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click to enlarge

America's coastal cities are in for a serious pounding over the course of the next 100 years, thanks to the ravages of climate change. Catastrophic flooding events along the east coast are projected to at least double by 2030, according to a 2014 report from the Union of Concerned Scientists. Across 76 pages and in more than 200 footnotes, the MIT-based group suggests that the mid-Atlantic region will be particularly hard hit: by 2030, Washington, D.C., will see more than 150 tidal floods annually. By 2045, the nation's capital will face one per day, or nearly 400 floods every year. Increases in monsoon, hurricane, and storm strengths will also have a substantial impact on the viability and safety of the country's coastal cities, as demonstrated in 2012 by Hurricane Sandy, which caused more than $50 billion dollars in economic losses and numerous deaths in New York, New Jersey, and elsewhere. Mean sea level is scheduled for a drastic increase, rising between 0.4 and 1.2 meters by 2100 if current rates of carbon emissions continue. Over the next 200 years, New York could lose the East Village, West Village, Williamsburg, and Long Island City to the sea, while Boston may be forced to become a city of canals.

On the west coast, unprecedented decreases in rainfall and increases in temperature are already presenting significant economic challenges, with University of California researchers reporting that the Golden State's 2015 drought cost its economy $1.8 billion dollars and more than 10,000 jobs. Moreover, a research team composed of scientists from NASA, Columbia, and Cornell recently published a study warning of unprecedented "megadrought" conditions affecting the American southwest within as few as 35 years, exponentially worsening California's present water problems and leading to voracious, uncontrollable wildfires on scales previously unimaginable. Between 1984 and 2011, the total area consumed by wildfires in the United States increased at a rate of approximately 90,000 acres per year-or a plot the size of the city of Las Vegas-costing hundreds of millions of dollars to combat annually, and that cost is expected to compound over time. Massive displacements due to fire are already taking place-one California fire last year resulted in the evacuation of more than 23,000 residents and a governor-declared state of emergency.

Comparatively, Chicago, the "Third Coast," is arguably far better situated to deal with climate change than its peer cities on either side of the country. Its geographic location will spare it some of the more dramatic impacts of climate change-including land loss to rising tides-while its cultural, economic, historical, and architectural significance will provide it a platform for future growth. As climate change forces cities such as New York, Washington, Philadelphia, and San Francisco into crisis, Chicago may reveal itself as the most resilient American legacy city.

The principal climate-related challenge Chicago itself faces is heat. Environmental Protection Agency researchers predict that the midwest as a whole will experience significant increases in temperature throughout the 21st century, with Chicago experiencing summer temperatures akin to those of present-day Atlanta before 2100. Projected decreases in summer and fall precipitation will render this heat particularly problematic. Fortunately, Chicago needn't be as concerned about drought and dwindling water supplies compared to other major cities due to its sizable neighbor, Lake Michigan. David Archer, a climate scientist at the University of Chicago, says Lake Michigan is enormously useful in a hotter and drier world, going so far as to call the Great Lakes region "the Saudi Arabia of freshwater" owing to the vast quantities we have of the wet stuff.

"We're much better off than NYC, which has real sea level [rise] and hurricane problems," Archer says. "LA is definitely in a precarious water situation, along with much of the rest of the southwest. Chicago is the place to be, it seems."

The Great Lakes' water resources will have to be allocated sustainably, though. Joseph Atkinson, director of the Great Lakes program at SUNY Buffalo, says the recent Great Lakes Compact is especially important in this regard. The agreement between eight U.S. states and two Canadian provinces prevents cities and townships outside the Great Lakes watershed from using its water. As cities outside the basin struggle to pull water from local aquifers and other groundwater resources, the compact could be tested by municipalities that want in.

However, "if this compact can stand up to legal challenges, there is a very good chance the Great Lakes water resource can be developed sustainably," Atkinson says. "There is a lot of science and engineering that is already developed to understand how to do that."

By the end of the century, Chicago can also expect precipitation increases of more than 40 percent during the winter and spring months, as well as more instances of heavy precipitation. While rainstorms frequently flood Chicago neighborhoods, the city has begun investing hundreds of millions of dollars in trees, rain barrels, permeable paving for alleyways, and other means to stem runoff in problematic areas. More importantly, the Metropolitan Water Reclamation District has spent decades building the "Deep Tunnel," a huge storm and wastewater system that will be able to handle 17.5 billion gallons of water overflow by 2030-a massive increase from its current 2.7 billion gallon capacity.

Beyond preparing for increased precipitation, Chicago is also remaking itself into a greener and more change-resilient metropolis in other ways. The New York Times has noted the primacy of Chicago among major American cities in its comprehensive planning and responses to a changing climate. From the initial green-roofing of City Hall in 2001 to the development of Millennium Park over rail lines and parking garages to the recent opening of the decade-in-the-making 2.7 mile 606 trailway, the last 20 years have borne witness to intensified greening and environmental conservation efforts within the city core. Regarding transit, Chicago has recently developed more than 300 miles of bikeways, with rail and subway use increasing by nearly 4 percent in 2014, reaching its highest level since Chicago first began tracking ridership in the 1960s. At the same time, numerous successful transit-oriented developments are gaining visibility across the city. The possibility for a massive reduction in automobile use is extraordinary, with 80 percent of the jobs situated within city limits accessible by public transit. Additionally, Chicago is ahead of the game when it comes to green-fitting its skyline. Illinois ranks first in the country in Leadership in Energy & Design-certified building space; Chicago has been cited for having the greatest number of LEED-certified buildings of any American city.

Changes are coming, whether we welcome them or not. Thankfully, Chicago has the natural resources, alongside the social, cultural, economic resources, to become the sort of sustainable, climate-change-resistant metropolis we will inevitably require in the future. If city officials continue to pave the way for greater resiliency, the "Second City" could be second to none in a world where Los Angeles runs dry and Manhattan is washed clean by storm surges. v

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Chicago is better poised to survive climate change than New York or LA

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click to enlarge America's coastal cities are in for a serious pounding over the course of the next 100 years, thanks to the ravages of climate change. Catastrophic flooding events along the east coast are projected to at least double by 2030, according to a 2014 report from the Union of Concerned Scientists.

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4. Compare global population numbers with rising carbon dioxide levels. Are they related? Explain. 

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4. Compare global population numbers with rising carbon dioxide levels. Are they related? Explain. 

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They are related since people exhale CO2. As the population increases, the amount of CO2 in the air increases.

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2. Why are some people skeptical of global warming? 

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2. Why are some people skeptical of global warming? 

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Rising sea levels is both a certain and uncertain impact of climate change. Sea levels rise and continuously change through centuries.

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Posted on 19 February 2019 by Guest Author

This is a re-post from Carbon Brief by Robert McSweeney

A widely reported study in 2016 that suggested Antarctica could add more than a metre to sea levels by 2100 was likely an "overestimate", new research says.

The original study, published in Nature, grabbed headlines with the finding that Antarctic ice was at risk from "marine ice-cliff instability", which would see towering cliffs of glacier ice collapse into the ocean under their own weight.

A new Nature study revisits the theory, finding that the "jury's definitely still out" on ice-cliff instability coming into play this century, the lead author tells Carbon Brief.

A second paper, also in Nature, says that melting of the Greenland and Antarctic ice sheets could have dramatic knock-on impacts for the climate. These include the potential weakening of the Atlantic current that brings warm water up to Europe from the tropics, and a positive feedback loop that reinforces melting of Antarctic ice.

The papers together suggest a likely contribution of around 15cm from melting Antarctic ice by the end of this century, with a 5% likelihood that it will exceed 39cm under a high-emissions scenario.

Rising seas

Global sea level rise is simultaneously one of the most certain and uncertain impacts of climate change.

On one hand, scientists know that sea levels will rise as the climate warms and then continue for centuries, even after global temperatures have stabilised.

On the other, however, there are sizeable question marks over the likely size and rate of sea level rise contributions from the Antarctic and Greenland ice sheets, which together hold enough ice to raise sea levels by tens of metres.

In 2016, a new study was published in Nature that caused quite a stir. It suggested that a previously unconsidered process, known as "marine ice-cliff instability" (MICI), meant the glaciers in the Antarctic were more unstable than scientists had thought. The paper concluded that "Antarctica has the potential to contribute more than a metre of sea level rise by 2100 and more than 15 metres by 2500".

Just a few years previously, the Intergovernmental Panel on Climate Change's (IPCC) fifth assessment report had estimated the likely contribution from the Antarctic ice sheet of between -6 and +12cm by 2081-2100 (pdf).

The 2016 study generated a lot of media coverage, even making the frontpage of the New York Times under the headline: "Ice sheet melt seen harming cities by 2100". Such was the scale of press attention, it became the most talked-about climate paper of that year.

Almost three years on, a new study - also published in Nature - has revisited the 2016 paper and undertaken further statistical analysis. The new findings question whether there is sufficient evidence to support MICI playing a role in sea level rise this century.

Ice-cliff instability

The quintessential video clip of a melting glacier shows a large chunk of ice breaking off its face and plunging into the sea. This process, known as "calving", occurs due to a combination of the glaciers' slow creep forward and the rifts that cut through the brittle ice. With a thunderous crack, unstable pieces of ice break off, depositing icebergs into the surrounding waters.

Marine ice-cliff instability is a similar process, but on a colossal scale. The theory goes that where the height of a glacier face exceeds around 100m above the ocean surface, the cliff will be too tall to support its own weight. It will, therefore, inevitably collapse, exposing a similarly tall cliff face behind it, which, too, will collapse, and so on.

At the moment, calving of ice cliffs "isn't widespread on Antarctica", says Prof Robert DeConto, a professor in the department of geosciences at the University of Massachusetts, Amherst and co-author of the 2016 Nature paper. This is "because most of the very thick ice reaching the ocean is supported by buttressing ice shelves".

This is where ice shelves - floating tongues of ice that flow out onto the water where a glacier meets the ocean - act to hold back, or "buttress", the ice behind them. However, "many of Antarctica's ice shelves are thinning in response to warm subsurface water temperatures", DeConto tells Carbon Brief:

"If the ice shelves are lost, tall ice cliffs will become exposed, stresses at the edge of the ice will increase, and the ice will begin to break like it is in Greenland - or possibly even faster. That's the concern. The loss of ice shelves is what sets this in motion."

The illustration below, from the 2016 paper, shows how the loss of an ice shelf allows warm water to reach an unstable cliff face, speeding up the melt and retreat of a glacier.

DeConto cites examples from Greenland as "the closest analogues of MICI in action today". The one kilometre-thick Jakobshavn glacier - among the fastest flowing glaciers in the world - is calving "at a frightfully rapid pace", he says, which is equivalent to "a horizontal rate of ice loss of around 13km per year". He notes:

"If the pace of calving observed at Jakobshavn were to become widespread around the edges of the vastly bigger Antarctic ice sheet, it could cause very fast sea level rise. This is the take home message from our 2016 paper and that basic conclusion remains unchanged."

In that 2016 paper, DeConto and his co-author, Prof David Pollard of Penn State University, used an ice sheet model to ascertain how periods in the Earth's history that were only slightly warmer than today managed to have sea levels that were many metres higher.

Simulating the Pliocene, around three million years ago, and the Last Interglacial, 130,000-115,000 years ago, DeConto and Pollard found that the high sea levels from those periods could only be recreated when MICI was included. DeConto explains:

"One key point is that including these brittle processes in ice sheet models is the best way we've found to reproduce the high sea levels we see in the geologic past."

Turning their attention to the future, DeConto and Pollard ran model simulations calibrated on their findings for the past. They found that including MICI "greatly increases the pace of future sea level rise in high greenhouse gas emissions scenarios", says DeConto.

The new paper revisits these estimates. It uses a statistical model, called an "emulator", to replicate the model created by DeConto and Pollard. This allowed the researchers to expand the number of model simulations they ran to explore the full range of possible future outcomes - including those that do not include MICI - as well as calibrating the model with satellite data.

In simulations with MICI, the "most likely" model outcome under the high-emissions RCP8.5 scenario is a contribution from Antarctica of 45cm by 2100, says lead author Dr Tamsin Edwards, a climate scientist and lecturer at King's College London. She tells Carbon Brief:

"This is much lower than the mean values in DeConto & Pollard - interpreted by many as the most likely values - which ranged from 64cm to 114 cm."

But their findings also suggest that MICI was not necessary to produce the sea level rise seen in the Pliocene or the Last Interglacial. Without MICI, their most likely contribution from Antarctica is 15cm by 2100 under RCP8.5, with a "likely" range of 13-31cm. There is just a 5% likelihood of Antarctica contributing more than 39cm to sea levels by 2100, Edwards says:

"This brings the DeConto and Pollard projections well into line with previous studies for this century, which have upper bounds of around 30-40cm under high warming scenarios.

"I would say we consider these to be more robust, because there just isn't enough evidence for MICI, or the simple way it is represented in their model."

The chart below shows the likelihood of Antarctica exceeding one metre of sea level rise in the new simulations. It includes three emissions scenarios: low ( RCP2.6, grey), intermediate ( RCP4.5, blue) and high ( RCP8.5, red), with and without MICI. The lines show how the probability changes through time.

So, for example, under high emissions with MICI, the likelihood of more than one metre of sea level rise from Antarctica emerges above zero around the 2080s, and rapidly increases until it becomes a certainty (within the model) in the 2130s. Without MICI, there is no risk of one metre of sea level rise within this century, but it does emerge relatively early in the 22nd century.

Only RCP2.6 - which is broadly consistent with the long-term goals of the 2015 Paris Agreement - is the only scenario "to ensure a low probability of high sea level rise", the paper notes.

Jury's out

The findings of the new study show that "the jury's definitely still out on MICI", says Edwards. There is a real lack of published studies that incorporate the process, she says, adding: "We really need much higher resolution models to try including it, which test different representations."

However, it certainly "does not mean that MICI is irrelevant and must be forgotten", says Dr Cyrille Mosbeux, a postdoctoral scholar at the Scripps Institution of Oceanography who was not involved in either study. He tells Carbon Brief: "We still need to take account for as many processes as possible" in sea level rise estimates.

As "very little is known about MICI and it is hard to predict its effect in the future", the new findings emphasise the need for improved models and continued observations around Antarctica, he adds.

While the study does "illustrate the need for more in-depth analysis than we originally applied to our 2016 model", says DeConto, he is concerned that the new findings "will be interpreted as evidence that marine ice-cliff calving doesn't happen and is not a potentially dangerous driver of rapid ice loss and sea level rise".

DeConto and Pollard are also currently revisiting their 2016 results in a new paper. DeConto says he is not able to comment on it directly as it is undergoing peer review. However, he has presented some preliminary results at the Fall Meeting of the American Geophysical Union (AGU) in December.

An article published in the Atlantic shortly afterwards reported that DeConto and Pollard "have lowered some of their worst-case projections for the 21st century" after making improvements to their model. The results are likely to put Antarctica's contribution to sea level rise in 2100 at "about a foot" (30cm), the article says, which is "much closer to projections made by other glaciologists".

Considering the theory of MICI was proposed less than eight years ago, it is still very early in terms of refining the estimates of what impact it could have. However, as scientific disagreements go, this is definitely the more cordial kind. Both DeConto and Pollard were originally co-authors on the new paper. They later recused themselves because they felt the results coming from Edwards's statistical model were not consistent with what they were seeing from their own physics-based glacier model.

In addition, Edwards says the pair have been "very supportive and helpful with this work", including running extra model simulations that she needed for her own statistical model.

Wider implications

In the second Nature paper out today, also co-authored by Edwards, researchers consider the wider impacts of ice sheet melt from both Antarctica and Greenland.

Climate models typically include "a dynamic atmosphere, ocean and sea ice, but do not consider changes in ice sheet size and volume", explains an accompanying Nature News & Views article written by Dr Helene Seroussi from Caltech's Jet Propulsion Laboratory.

This is because ice sheets tend to change on very long timescales and so are "assumed to have no effect on other components of the climate system for simulations that cover a few centuries", says Seroussi. The new study does include these dynamic responses, by modelling the impacts of the influx of meltwater from ice sheets into the oceans.

The findings suggest there could be far-reaching consequences. For example, freshwater flooding into the North Atlantic from the Greenland ice sheet is projected to cause a gradual slowing of the "Atlantic Meridional Overturning Circulation" (AMOC), a perpetual conveyor belt that transports heat from the equator up to the North Atlantic. Under the high-emissions RCP8.5 scenario, "a gradual slowing in the first half of the century steepens after 2050", the paper says, leading to a 15% weakening over 50 years.

In the southern hemisphere, the study finds that meltwater from the Antarctic ice sheet could "trap warm water below the sea surface". This could create a positive feedback loop where the trapped warm water enhances melting of Antarctic ice shelves, leading to greater loss of ice.

This has implications for sea levels. The study projects a combined contribution of 25cm to global sea levels by 2100 from Antarctica and Greenland.

The findings suggest a larger contribution from Antarctica than the IPCC's fifth assessment report (AR5), explains Dr Nick Golledge, associate professor at Victoria University of Wellington's Antarctic Research Centre and lead author of the paper. He tells Carbon Brief:

"AR5 gave mean contributions for 2081-2100 of 4cm from Antarctica and 12cm from Greenland. In our new study, we suggest 14cm from Antarctica and 11cm from Greenland at 2100, so an increase to the Antarctic term and just above the upper bound of the AR5 uncertainty range (-6 cm to 12 cm)."

As these projections do not include MICI, they are comparable to the 15cm "most likely" projection from the MICI study.

Despite using different approaches, the two new sets of findings "show relatively good agreement", says Cyrille Mosbeux, with both forecasting an Antarctic contribution to sea levels of "up to a few tenths of centimetres...which agree more with other studies".

The two studies "demonstrate that polar ice sheets will have a crucial role in Earth's climate in the future", concludes Seroussi's commentary article, "and highlight the need to explore the two-way coupling between the ice sheets and other climate components".

Edwards, T. L. et al. (2019) Revisiting Antarctic ice loss due to marine ice-cliff instability, Nature, doi:10.1038/s41586-019-0901-4

Golledge, N. R. et al. (2019) Global environmental consequences of twenty-first-century ice-sheet melt, Nature, doi:10.1038/s41586-019-0889-9

Seroussi, H. (2019) Fate and future role of polar ice sheets, Nature

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Studies shed new light on Antarctica's future contribution to sea level rise

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Posted on 19 February 2019 by Guest Author This is a re-post from Carbon Brief by Robert McSweeney A widely reported study in 2016 that suggested Antarctica could add more than a metre to sea levels by 2100 was likely an "overestimate", new research says.