Climate change odds much worse than thoughtMay 20, 2009The most comprehensive modeling yet carried out on the likelihood of how much hotter the Earth's climate will get in this century shows that without rapid and massive action, the problem will be about twice as severe as previously estimated six years ago - and could be even worse than that. The study uses the MIT Integrated Global Systems Model, a detailed computer simulation of global economic activity and climate processes that has been developed and refined by the Joint Program on the Science and Policy of Global Change since the early 1990s. The new research involved 400 runs of the model with each run using slight variations in input parameters, selected so that each run has about an equal probability of being correct based on present observations and knowledge. Other research groups have estimated the probabilities of various outcomes, based on variations in the physical response of the climate system itself. But the MIT model is the only one that interactively includes detailed treatment of possible changes in human activities as well - such as the degree of economic growth, with its associated energy use, in different countries. Study co-author Ronald Prinn, the co-director of the Joint Program and director of MIT's Center for Global Change Science, says that, regarding global warming, it is important "to base our opinions and policies on the peer-reviewed science," he says. And in the peer-reviewed literature, the MIT model, unlike any other, looks in great detail at the effects of economic activity coupled with the effects of atmospheric, oceanic and biological systems. "In that sense, our work is unique," he says. The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees. The difference is caused by several factors rather than any single big change. Among these are improved economic modeling and newer economic data showing less chance of low emissions than had been projected in the earlier scenarios. Other changes include accounting for the past masking of underlying warming by the cooling induced by 20th century volcanoes, and for emissions of soot, which can add to the warming effect. In addition, measurements of deep ocean temperature rises, which enable estimates of how fast heat and carbon dioxide are removed from the atmosphere and transferred to the ocean depths, imply lower transfer rates than previously estimated. Prinn says these and a variety of other changes based on new measurements and new analyses changed the odds on what could be expected in this century in the "no policy" scenarios - that is, where there are no policies in place that specifically induce reductions in greenhouse gas emissions. Overall, the changes "unfortunately largely summed up all in the same direction," he says. "Overall, they stacked up so they caused more projected global warming." While the outcomes in the "no policy" projections now look much worse than before, there is less change from previous work in the projected outcomes if strong policies are put in place now to drastically curb greenhouse gas emissions. Without action, "there is significantly more risk than we previously estimated," Prinn says. "This increases the urgency for significant policy action." To illustrate the range of probabilities revealed by the 400 simulations, Prinn and the team produced a "roulette wheel" that reflects the latest relative odds of various levels of temperature rise. The wheel provides a very graphic representation of just how serious the potential climate impacts are. "There's no way the world can or should take these risks," Prinn says. And the odds indicated by this modeling may actually understate the problem, because the model does not fully incorporate other positive feedbacks that can occur, for example, if increased temperatures caused a large-scale melting of permafrost in arctic regions and subsequent release of large quantities of methane, a very potent greenhouse gas. Including that feedback "is just going to make it worse," Prinn says. The lead author of the paper describing the new projections is Andrei Sokolov, research scientist in the Joint Program. Other authors, besides Sokolov and Prinn, include Peter H. Stone, Chris E. Forest, Sergey Paltsev, Adam Schlosser, Stephanie Dutkiewicz, John Reilly, Marcus Sarofim, Chien Wang and Henry D. Jacoby, all of the MIT Joint Program on the Science and Policy of Global Change, as well as Mort Webster of MIT's Engineering Systems Division and D. Kicklighter, B. Felzer and J. Melillo of the Marine Biological Laboratory at Woods Hole. Prinn stresses that the computer models are built to match the known conditions, processes and past history of the relevant human and natural systems, and the researchers are therefore dependent on the accuracy of this current knowledge. Beyond this, "we do the research, and let the results fall where they may," he says. Since there are so many uncertainties, especially with regard to what human beings will choose to do and how large the climate response will be, "we don't pretend we can do it accurately. Instead, we do these 400 runs and look at the spread of the odds." Because vehicles last for years, and buildings and powerplants last for decades, it is essential to start making major changes through adoption of significant national and international policies as soon as possible, Prinn says. "The least-cost option to lower the risk is to start now and steadily transform the global energy system over the coming decades to low or zero greenhouse gas-emitting technologies." This work was supported in part by grants from the Office of Science of the U.S. Dept. of Energy, and by the industrial and foundation sponsors of the MIT Joint Program on the Science and Policy of Global Change. Massachusetts Institute of Technology |
|||||||||||||||||||||
| Related Climate Change Current Events and Climate Change News Articles Flax and yellow flowers can produce bioethanol Surplus biomass from the production of flax shives, and generated from Brassica carinata, a yellow-flowered plant related to those which engulf fields in spring, can be used to produce bioethanol. Aquatic creatures mix ocean water Understanding mixing in the ocean is of fundamental importance to modeling climate change or predicting the effects of an El Niño on our weather. Modern ocean models primarily incorporate the effects of winds and tides. However, they do not generally take into account the mixing generated by swimming animals. How green is your house? Preliminary results from 1500 respondents show that those who own their own home are more likely to separate their rubbish (83 per cent) than those in rented accommodation (59 per cent), whilst less than one in a hundred households have solar water heating (0.5 per cent) or solar energy panels (0.5 per cent). Initial findings also show that switching off the lights in unused rooms (82 per cent) and not leaving the television on standby (67 per cent) are significantly more popular than taking fewer flights (16 per cent), car sharing (15 per cent) and not buying items because they have too much packaging (8 per cent). Scientists at UA, collaborating institutions decode maize genome Scientists from the University of Arizona led by Arizona Genomics Institute director Rod A. Wing and from collaborating institutions have deciphered the complete genetic code of the maize plant for the first time. 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. Research challenges for understanding landscape changes identified Nine research challenges and four research initiatives that are poised to advance the study of how Earth's landscapes change were unveiled today in a new report by the National Research Council. Berkeley Lab Lends Expertise to India to Promote Energy Efficiency ndia may rank only a distant fourth in terms of carbon dioxide emissions, behind China, the United States and Russia, but its rapid economic growth rate coupled with aging and inefficient energy infrastructure suggest dire environmental consequences if "business as usual" continues. Experts: Failure to focus on farming will undermine global climate agreement and increase hunger Alarmed by a substantial oversight in the global climate talks leading up to the United Nations Climate Change Conference in Copenhagen next month, more than 60 of the world's most prominent agricultural scientists and leaders underscored how the almost total absence of agriculture in the agreement could lead to widespread famine and food shortages in the years ahead. Study: Sea stars bulk up to beat the heat A new study finds that a species of sea star stays cool using a strategy never before seen in the animal kingdom. The sea stars soak up cold sea water into their bodies during high tide as buffer against potentially damaging temperatures brought about by direct sunlight at low tide. Emulating Western lifestyles: Consumption and carbon footprints in less industrialized countries In recent decades, a new global middle class has exploded, with a total population exceeding one billion people. A new study in the Journal of Consumer Research explores the consumption attitudes of some of these members of the "new class." More Climate Change Current Events and Climate Change News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||