Research finds that Earth's climate is approaching 'dangerous' pointJune 01, 2007NASA and Columbia University Earth Institute research finds that human-made greenhouse gases have brought the Earth's climate close to critical tipping points, with potentially dangerous consequences for the planet. From a combination of climate models, satellite data, and paleoclimate records the scientists conclude that the West Antarctic ice sheet, Arctic ice cover, and regions providing fresh water sources and species habitat are under threat from continued global warming. The research appears in the current issue of Atmospheric Chemistry and Physics. Tipping points can occur during climate change when the climate reaches a state such that strong amplifying feedbacks are activated by only moderate additional warming. This study finds that global warming of 0.6°C in the past 30 years has been driven mainly by increasing greenhouse gases, and only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice. Amplifying feedbacks include increased absorption of sunlight as melting exposes darker surfaces and speedup of iceberg discharge as the warming ocean melts ice shelves that otherwise inhibit ice flow. The researchers used data on earlier warm periods in Earth's history to estimate climate impacts as a function of global temperature, climate models to simulate global warming, and satellite data to verify ongoing changes. Lead author James Hansen, NASA Goddard Institute for Space Studies, New York, concludes: "If global emissions of carbon dioxide continue to rise at the rate of the past decade, this research shows that there will be disastrous effects, including increasingly rapid sea level rise, increased frequency of droughts and floods, and increased stress on wildlife and plants due to rapidly shifting climate zones." The researchers also investigate what would be needed to avert large climate change, thus helping define practical implications of the United Nations Framework Convention on Climate Change. That treaty, signed in 1992 by the United States and almost all nations of the world, has the goal to stabilize atmospheric greenhouse gases "at a level that prevents dangerous human-made interference with the climate system." Based on climate model studies and the history of the Earth the authors conclude that additional global warming of about 1°C (1.8°F) or more, above global temperature in 2000, is likely to be dangerous. In turn, the temperature limit has implications for atmospheric carbon dioxide (CO2), which has already increased from the pre-industrial level of 280 parts per million (ppm) to 383 ppm today and is rising by about 2 ppm per year. According to study co-author Makiko Sato of Columbia's Earth Institute, "the temperature limit implies that CO2 exceeding 450 ppm is almost surely dangerous, and the ceiling may be even lower." The study also shows that the reduction of non-carbon dioxide forcings such as methane and black soot can offset some CO2 increase, but only to a limited extent. Hansen notes that "we probably need a full court press on both CO2 emission rates and non-CO2 forcings, to avoid tipping points and save Arctic sea ice and the West Antarctic ice sheet." A computer model developed by the Goddard Institute was used to simulate climate from 1880 through today. The model included a more comprehensive set of natural and human-made climate forcings than previous studies, including changes in solar radiation, volcanic particles, human-made greenhouse gases, fine particles such as soot, the effect of the particles on clouds and land use. Extensive evaluation of the model's ability to simulate climate change is contained in a companion paper to be published in Climate Dynamics. The authors use the model for climate simulations of the 21st century using both 'business-as-usual' growth of greenhouse gas emissions and an 'alternative scenario' in which emissions decrease slowly in the next few decades and then rapidly to achieve stabilization of atmospheric CO2 amount by the end of the century. Climate changes are so large with 'business-as-usual', with additional global warming of 2-3°C (3.6-5.4°F) that Hansen concludes "'business-as-usual' would be a guarantee of global and regional disasters." However, the study finds much less severe climate change - one-quarter to one-third that of the "business-as-usual" scenario - when greenhouse gas emissions follow the alternative scenario. "Climate effects may still be substantial in the 'alternative scenario', but there is a better chance to adapt to the changes and find other ways to further reduce the climate change," said Sato. While the researchers say it is still possible to achieve the "alternative scenario," they note that significant actions will be required to do so. Emissions must begin to slow soon. "With another decade of 'business-as-usual' it becomes impractical to achieve the 'alternative scenario' because of the energy infrastructure that would be in place" says Hansen. NASA/Goddard Space Flight Center |
|||||||||||||||||||||
| Related Greenhouse Gas Current Events and Greenhouse Gas News Articles ORNL, Los Alamos pioneer new approach to assist scientists, farmers Sustainable farming, initially adopted to preserve soil quality for future generations, may also play a role in maintaining a healthy climate, according to researchers at the Department of Energy's Oak Ridge and Los Alamos national laboratories. TEEB report released on the economics of ecosystems and biodiversity for policy makers Policy makers who factor the planet's multi-trillion dollar ecosystem services into their national and international investment strategies are likely to see far higher rates of return and stronger economic growth in the 21st century. Record highs far outpace record lows across US Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. UT Knoxville and ORNL researchers turn algae into high-temperature hydrogen source In the quest to make hydrogen as a clean alternative fuel source, researchers have been stymied about how to create usable hydrogen that is clean and sustainable without relying on an intensive, high-energy process that outweighs the benefits of not using petroleum to power vehicles. Controversial new climate change results New data show that the balance between the airborne and the absorbed fraction of carbon dioxide has stayed approximately constant since 1850, despite emissions of carbon dioxide having risen from about 2 billion tons a year in 1850 to 35 billion tons a year now. Reducing greenhouse gases may not be enough to slow climate change Because land use changes are responsible for 50 percent of warming in the US, policymakers need to address the influence of global deforestation and urbanization on climate change, in addition to greenhouse gas emissions. Researchers Hail Innovative Plan to Save Rainforest, Reduce Greenhouse Gas Emissions An innovative proposal by the Ecuadorian government to protect an untouched, oil rich region of Amazon rainforest is a precedent-setting and potentially economically viable approach, says a team of environmental researchers from the University of Maryland, the World Resources Institute and Save America's Forests. Report on US-China collaboration on carbon capture and sequestration Lawrence Livermore National Laboratory's Julio Friedmann, in collaboration with the Center for American Progress, the Asia Society Center and with partner Monitor Group, today released the report, "A Roadmap for U.S.-China Collaboration on Carbon Capture and Sequestration." Study gives clearer picture of how land-use changes affect U.S. climate Researchers say regional surface temperatures can be affected by land use, suggesting that local and regional strategies, such as creating green spaces and buffer zones in and around urban areas, could be a tool in addressing climate change. Iron controls patterns of nitrogen fixation in the Atlantic Scientists including researchers from the National Oceanography Centre, Southampton and the University of Essex have discovered that interactions between iron supply, transported through the atmosphere from deserts, and large-scale oceanic circulation control the availability of a crucial nutrient, nitrogen, in the Atlantic. More Greenhouse Gas Current Events and Greenhouse Gas News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||