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Friday, August 7, 2009

Global warming: is two degress target realistic ?

John Wihbey | August 4, 2009, reports in Yele Forum . The G-8, eight Northern Hemisphere industrialized countries, last month produced its first firm target for curbing rising global temperatures: no more than 2 degrees Celsius (3.6 Fahrenheit), above pre-industrial levels.
The “2 degrees” has now been semi-enshrined as the consensus “magic number” for avoiding dangerous climate change. The idea of this two-degree limit Celsius has a long scientific history stretching back to the 1980s. It started to be cemented in policy circles after the European Union (EU) adopted the target in 1996.

Through 2008, the global average temperature had already warmed roughly 0.7 degrees Celsius, above pre-industrial levels, meaning that by some measures we are already one third of the way toward hitting the 2 degree ceiling.The temperature is now rising faster than in earlier decades in the 20th century.

The meaning of that simple number is quite complex. It involves some subjective analysis. A Delicate Compromise and a Value Judgment. It is a delicate compromise between what is desirable and what may be feasible. The IPCC chairman, Rajendra Pachauri, has said that the whole issue of 2 degrees versus 1 degree or 1.5 degree is something based on a value judgment that essentially relates to what is dangerous, in terms of making it almost impossible for some people on this planet not being able to live in those locations. In other words, the temperature target may be too high for some people in the developing world, who are already vulnerable. Any number much above 1 degree involves a gamble, and the odds become less and less favorable as the temperature goes up.

The IPCC’s 2007 report states that even 2 degrees Celsius above pre-industrial levels is likely to have serious impacts, especially in terms of stressing water supplies and creating more malnutrition, disease, and drought. The climate scientists believe that even a ‘moderate’ warming of 2 degrees C stands a strong chance of provoking drought and storm responses that could challenge civilized society, leading potentially to the conflict and suffering that go with failed states and mass migrations.

The tipping point idea has been debated in the media and in scientific circles, with no precise number or scenario agreed upon. But there are real worries.

James McCarthy, professor of biological oceanography at Harvard University and the current President of the American Association for the Advancement of Science, said that the closer the planet comes to a global average rise of 2 degrees Celsius, the less likely we are to be able to avoid climbing to even higher temperatures. Models suggest that feedback cycles could afflict both the tundra - where scientists fear a massive carbon release - and the Amazon forest ecosystem, which could rapidly dry up, McCarthy noted.

Some observers point out that the debate over 2 degrees involves two interrelated questions that are often blurred. First, how does the temperature goal stand up scientifically - i.e., would it still prevent perilous ocean level rise, large-scale drought, loss of ecosystems, dangerous weather, etc.?

Second, how does the target operate as a policy tool and as a piece of rhetoric in global negotiations?

We should be talking about emissions targets, and the right emission target is zero. We are going to solve the carbon-climate problem when we create an understanding that it is no longer acceptable to use the atmosphere as a waste dump. There should no discussion about targets, it should be a discussion about which kinds of objects people should be allowed to build.

There is indeed a vigorous debate between the developing world and the G-8 over this very question. The industrialized countries tend to talk about “common” goals in terms of reducing emissions. By contrast, developing countries focus on “differentiated” responsibilities - namely the need for the big industrial nations to take the deeper emissions cuts. The developing countries see the 2 degrees goal as a vague notion that does not put pressure on individual countries, since no one nation can control global temperature.

John Wihbey, a regular contributor to The Yale Forum, is a producer for an NPR show. He previously reported on environmental issues for The Star-Ledger in Newark, N.J. (E-mail: jpwihb@yahoo.com)

IPCC Report on Climate Change