Substream - sub_gw_impact_permafrost

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  2. 25-02-2004 eco nws - global warming - impact - system - permafrost - The permafrost in the bogs of subarctic Sweden is undergoing dramatic changes. The part of the soil that thaws in the summer, the so-called active layer, has become thicker since 1970, and the permafrost has disappeared altogether in some locations. This has lead to significant changes in vegetation and to a subsequent increase in emission of the greenhouse gas methane. Methane is 25 times more potent than carbon dioxide as a greenhouse gas. Behind these new findings is an international research team led by the GeoBiosphere Science Centre at Lund University in Sweden. The results were published 20 February in Geophysical Research Letters. The researchers say their results are unique, as there are very few places in the circumpolar North where comparison of observations over a period of decades is possible.

  3. 15-11-2004 eco nws - global warming - impact - arctic - arctic heating faster - Earth's climate has warmed by about 1 degree Fahrenheit since 1900. In the Arctic, where a number of processes amplify the warming effects of carbon dioxide, most regions have experienced a temperature rise of 4 to 7 degrees in the last 50 years. That warmth has reduced the amount of snow that falls every winter, melted away mountain glaciers and shrunk the Arctic Ocean's summer sea ice cover to its smallest extent in millennia, according to satellite measurements. Swaths of Alaskan permafrost are thawing into soggy bogs, and trees are moving northward at the expense of the tundra that rings the Arctic Ocean. (enn)

  4. 17-02-2011 eco nws - global warming - impact - system - feedback - permafrost - Thawing Permafrost Likely Will Accelerate Global Warming, Study Finds - ScienceDaily (Feb. 17, 2011) � Up to two-thirds of Earth's permafrost likely will disappear by 2200 as a result of warming temperatures, unleashing vast quantities of carbon into the atmosphere, says a new study by the University of Colorado Boulder's Cooperative Institute for Research in Environmental Sciences. The carbon resides in permanently frozen ground that is beginning to thaw in high latitudes from warming temperatures, which will impact not only the climate but also international strategies to reduce fossil fuel emissions, said CU-Boulder's Kevin Schaefer, lead study author. "If we want to hit a target carbon dioxide concentration, then we have to reduce fossil fuel emissions that much lower than previously thought to account for this additional carbon from the permafrost," he said. "Otherwise we will end up with a warmer Earth than we want." The escaping carbon comes from plant material, primarily roots trapped and frozen in soil during the last glacial period that ended roughly 12,000 years ago, he said. Schaefer, a research associate at CU-Boulder's National Snow and Ice Data Center, an arm of CIRES, likened the mechanism to storing broccoli in a home freezer. "As long as it stays frozen, it stays stable for many years," he said. "But if you take it out of the freezer it will thaw out and decay." While other studies have shown carbon has begun to leak out of permafrost in Alaska and Siberia, the study by Schaefer and his colleagues is the first to make actual estimates of future carbon release from permafrost. "This gives us a starting point, and something more solid to work from in future studies," he said. "We now have some estimated numbers and dates to work with." Schaefer and his team ran multiple Arctic simulations assuming different rates of temperature increases to forecast how much carbon may be released globally from permafrost in the next two centuries. They estimate a release of roughly 190 billion tons of carbon, most of it in the next 100 years. The team used Intergovernmental Panel on Climate Change scenarios and land-surface models for the study. "The amount we expect to be released by permafrost is equivalent to half of the amount of carbon released since the dawn of the Industrial Age," said Schaefer. The amount of carbon predicted for release between now and 2200 is about one-fifth of the total amount of carbon in the atmosphere today, according to the study. While there were about 280 parts per million of CO2 in Earth's atmosphere prior to the Industrial Age beginning about 1820, there are more than 380 parts per million of carbon now in the atmosphere and the figure is rising. The increase, equivalent to about 435 billion tons of carbon, resulted primarily from human activities like the burning of fossil fuels and deforestation. Using data from all climate simulations, the team estimated that about 30 to 60 percent of Earth's permafrost will disappear by 2200. The study took into account all of the permanently frozen ground at high latitudes around the globe. The consensus of the vast majority of climate scientists is that the buildup of CO2 and other greenhouse gases in Earth's atmosphere is the primary reason for increasingly warm temperatures on Earth. According to NOAA, 2010 was tied for the hottest year on record. The hottest decade on record occurred from 2000 to 2010. Greater reductions in fossil fuel emissions to account for carbon released by the permafrost will be a daunting global challenge, Schaefer said. "The problem is getting more and more difficult all the time," he said. "It is hard enough to reduce the emissions in any case, but now we have to reduce emissions even more. We think it is important to get that message out now."

  5. 23-08-2011 eco nws - global warming - impact - permafrost - atmosphere - co2 - Permafrost Could Release Vast Amounts of Carbon and Accelerate Climate Change by End of Century - ScienceDaily (Aug. 23, 2011) � Billions of tons of carbon trapped in high-latitude permafrost may be released into the atmosphere by the end of this century as Earth's climate changes, further accelerating global warming, a new computer modeling study indicates. The study also found that soil in high-latitude regions could shift from being a sink to a source of carbon dioxide by the end of the 21st century as the soil warms in response to climate change. The research was led by Charles Koven of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). He conducted the research with a team of scientists from France, Canada, and the United Kingdom while he was a postdoctoral researcher at France's Laboratoire des Sciences du Climat et de l'Environnement. The modeling was conducted at a supercomputing facility run by France's Alternative Energies and Atomic Energy Commission. Their study was published online in the Proceedings of the National Academy of Sciences. Their findings counter results from a comparison of models that was included in the Intergovernmental Panel on Climate Change's 2007 fourth assessment report. The comparison found that climate change will spark a growth in high-latitude vegetation, which will pull in more carbon from the atmosphere than thawing permafrost will release. But unlike earlier models, the new model includes detailed processes of how carbon accumulates in high-latitude soil over millennia, and how it's released as permafrost thaws. Because it includes these processes, the model begins with much more carbon in the soil than previous models. It also better represents the carbon's vulnerability to decomposition as the soil warms. As a result, the new model found that the increase in carbon uptake by more vegetation will be overshadowed by a much larger amount of carbon released into the atmosphere. "Including permafrost processes turns out to be very important," says Koven, who joined Berkeley Lab's Earth Sciences Division as a staff scientist earlier this year. "Previous models tended to dramatically underestimate the amount of soil carbon at high latitudes because they lacked the processes of how carbon builds up in soil. Our model starts off with more carbon in the soil, so there is much more to lose with global warming." Koven and colleagues set out to estimate how much carbon dioxide and methane (which contains carbon) could be released by boreal and Arctic land ecosystems as a result of climate change. These regions are crucial to the global carbon cycle because they are rich in soil organic carbon, which has built up in frozen soils and peat layers over thousands of years. Much of this carbon is presently trapped and not cycling. But scientists believe that some of it could be released in response to warming and become a positive feedback to global climate change. At stake is an estimated 2,167 petagrams of carbon in all layers of high-latitude soil, which is more than two trillion U.S. tons. The scientists modified a land surface ecosystem model called ORCHIDEE to account for how carbon behaves at different layers, such as at the surface versus 30 centimeters below ground. They also accounted for the rate of soil carbon decomposition as a function of temperature at the freeze-thaw boundary, which sinks deeper and deeper as soil warms. Other improvements include soil physics that more realistically capture the effects of organic matter on carbon. Most other models do not have all of these phenomena. To determine how these processes affect the balance of carbon dioxide and methane in high-latitude soils, the scientists ran four simulations from 1860 to 2100, each with a different assortment of processes. They added in a middle-of-the-road climate change scenario that caused high-latitude surface soil to rise 8 degrees Celsius by 2100, which is much greater than the global average. The simulations revealed a climate-induced loss of between 25 and 85 petagrams of carbon, depending on the processes included. The best estimate is from a simulation that includes all of the permafrost soil processes. It found that 62 petagrams of soil carbon will be released into the atmosphere by 2100, or about 68 billion U.S. tons. This release of carbon is equivalent to an additional 7.5 years of global anthropogenic emissions at today's rate. The simulation also found only a slight increase in methane release, which is contrary to previous predictions. "People have this idea that permafrost thaw will release methane," says Koven. "But whether carbon comes out as carbon dioxide or methane is dependent on hydrology and other fine-scale processes that models have a poor ability to resolve. It's possible that warming at high latitudes leads to drying in many regions, and thus less methane emissions, and in fact this is what we found." Koven adds that there are large uncertainties in the model that need to be addressed, such as the role of nitrogen feedbacks, which affect plant growth. And he says that more research is needed to better understand the processes that cause carbon to be released in permanently frozen, seasonally frozen, and thawed soil layers. Researchers in Berkeley Lab's Earth Sciences Division are focusing on improving global climate model representations of these processes under two Department of Energy-funded projects.

  6. 30-11-2011 eco nws - global warming - impact - weather - views - Climate Change May Happen More Quickly Than Expected - ScienceDaily (Nov. 30, 2011) � As global temperatures continue to rise at an accelerated rate due to deforestation and the burning of fossil fuels, natural stores of carbon in the Arctic are cause for serious concern, researchers say. In an article scheduled to be published Dec. 1 in the journal Nature, a survey of 41 international experts led by University of Florida ecologist Edward Schuur shows models created to estimate global warming may have underestimated the magnitude of carbon emissions from permafrost over the next century. Its effect on climate change is projected to be 2.5 times greater than models predicted, partly because of the amount of methane released in permafrost, or frozen soil. "We're talking about carbon that's in soil, just like in your garden where there's compost containing carbon slowly breaking down, but in permafrost it's almost stopped because the soil is frozen," Schuur said. "As that soil warms up, that carbon can be broken down by bacteria and fungi, and as they metabolize, they are releasing carbon and methane, greenhouse gases that cause warmer temperatures." As a result of plant and animal remains decomposing for thousands of years, organic carbon in the permafrost zone is distributed across 11.7 million square miles of land, an amount that is more than three times larger than previously estimated. The new number is mainly based on evidence the carbon is stored much deeper as the result of observations, soil measurements and experiments. "We know the models are not yet giving us the right answer -- it's going to take time and development to make those better, and that process is not finished yet," Schuur said. "It's an interesting exercise in watching how scientists, who are very cautious in their training, make hypotheses about what our future will look like. The numbers are significant, and they appear like they are plausible and they are large enough for significant concern, because if climate change goes 20 or 30 percent faster that we had predicted already, that's a pretty big boost." The survey, which was completed following a National Science Foundation-funded Permafrost Carbon Network workshop about six months ago, proposed four warming scenarios until 2040, 2100 and 2300. Researchers were asked to predict the amount of permafrost likely to thaw, how much carbon would be released, and what amount would be methane, which has much more warming potential than carbon dioxide. The occurrence of carbon in northern soils is natural and the chemical does not have an effect on climate if it remains underground, but when released as a greenhouse gas it can add to climate warming. However, humans could slow warming temperatures as the result of greenhouse gas emissions from deforestation and the burning of fossil fuels, which are what speed up the process of permafrost thaw. "Even though we're talking about a place that is very far away and seems to be out of our control, we actually have influence over what happens based on the overall trajectory of warming. If we followed a lower trajectory of warming based on controlling emissions from the burning of fossil fuels, it has the effect of slowing the whole process down and keeping a lot more carbon in the ground," Schuur said. "Just by addressing the source of emissions that are from humans, we have this potential to just keep everything closer to its current state, frozen in permafrost, rather than going into the atmosphere." The survey shows that by 2100, experts believe the amount of carbon released will be 1.7 to 5.2 times greater than previous models predict, under scenarios where Arctic temperatures rise 13.5 degrees Fahrenheit. Some predicted effects of global warming include sea level rise, loss of biodiversity as some organisms are unable to migrate as quickly as the climate shifts and more extreme weather events that could affect food supply and water resources. "This new research shows that the unmanaged part of the biosphere has a major role in determining the future trajectory of climate change," said Stanford University biology professor Christopher Field, who was not involved in the study. "The implication is sobering. Whatever target we set for atmospheric CO2, this new research means we will need to work harder to reach it. But of course, limiting the amount of climate change also decreases the climate damage from permafrost melting." When carbon is released from the ground as a result of thawing permafrost, there is no way of trapping the gases at the source, so action to slow its effect must be taken beforehand. "If you think about fossil fuel and deforestation, those are things people are doing, so presumably if you had enough will, you could change your laws and adjust your society to slow some of that down," Schuur said. "But when carbon starts being emitted from the permafrost, you can't immediately say, 'OK, we've had enough of this, let's just stop doing it,' because it's a natural cycle emitting carbon whether you like it or not. Once we start pushing it, it's going to be releasing under its own dynamic."