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Varias lanchas de Greenpeace fueron hundidas y uno de los activistas fue herido por un arpón.


David Chandler, MIT News Office
May 19, 2009
The 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.
Extra-soft, quilted and multi-ply toilet roll made from virgin forest causes more damage than gas-guzzlers, fast food or McMansions, say campaigners

The tenderness of the delicate American buttock is causing more environmental devastation than the country's love of gas-guzzling cars, fast food or McMansions, according to green campaigners. At fault, they say, is the US public's insistence on extra-soft, quilted and multi-ply products when they use the bathroom.
"This is a product that we use for less than three seconds and the ecological consequences of manufacturing it from trees is enormous," said Allen Hershkowitz, a senior scientist at the Natural Resources Defence Council.
"Future generations are going to look at the way we make toilet paper as one of the greatest excesses of our age. Making toilet paper from virgin wood is a lot worse than driving Hummers in terms of global warming pollution." Making toilet paper has a significant impact because of chemicals used in pulp manufacture and cutting down forests.
A campaign by Greenpeace seeks to raise consciousness among Americans about the environmental costs of their toilet habits and counter an aggressive new push by the paper industry giants to market so-called luxury brands.
More than 98% of the toilet roll sold in America comes from virgin forests, said Hershkowitz. In Europe and Latin America, up to 40% of toilet paper comes from recycled products. Greenpeace this week launched a cut-out-and-keep ecological ranking of toilet paper products.
"We have this myth in the US that recycled is just so low quality, it's like cardboard and is impossible to use," said Lindsey Allen, the forestry campaigner of Greenpeace.
The campaigning group says it produced the guide to counter an aggressive marketing push by the big paper product makers in which celebrities talk about the comforts of luxury brands of toilet paper and tissue.
Those brands, which put quilting and pockets of air between several layers of paper, are especially damaging to the environment.
Paper manufacturers such as Kimberly-Clark have identified luxury brands such as three-ply tissues or tissues infused with hand lotion as the fastest-growing market share in a highly competitive industry. Its latest television advertisements show a woman caressing tissue infused with hand lotion.
The New York Times reported a 40% in sales of luxury brands of toilet paper in 2008. Paper companies are anxious to keep those percentages up, even as the recession bites. And Reuters reported that Kimberly-Clark spent $25m in its third quarter on advertising to persuade Americans against trusting their bottoms to cheaper brands.
But Kimberly-Clark, which touts its green credentials on its website, rejects the idea that it is pushing destructive products on an unwitting American public.
Dave Dixon, a company spokesman, said toilet paper and tissue from recycled fibre had been on the market for years. If Americans wanted to buy them, they could.
"For bath tissue Americans in particular like the softness and strength that virgin fibres provides," Dixon said. "It's the quality and softness the consumers in America have come to expect."
Longer fibres in virgin wood are easier to lay out and fluff up for a softer tissue. Dixon said the company used products from sustainbly farmed forests in Canada.
Americans already consume vastly more paper than any other country — about three times more per person than the average European, and 100 times more than the average person in China.
Barely a third of the paper products sold in America are from recycled sources — most of it comes from virgin forests.
"I really do think it is overwhelmingly an American phenomenom," said Hershkowitz. "People just don't understand that softness equals ecological destruction."
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