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1、 World must adapt to unknown climate future, says IPCC There is still great uncertainty about the impacts of climate change, according to the latest report from the Intergovernmental Panel on Climate Change, released today. So if we are to survive and prosper, rather than trying to fend off specific
2、 threats like cyclones, we must build flexible and resilient societies. Todays report is the second of three instalments of the IPCCs fifth assessment of climate change. The first instalment, released last year, covered the physical science of climate change. It stated with increased certainty that
3、climate change is happening, and that it is the result of humanitys greenhouse gas emissions. The new report focuses on the impacts of climate change and how to adapt to them. The third instalment, on how to cut greenhouse gas emissions, comes out in April. The latest report backs off from some of t
4、he predictions made in the previous IPCC report, in 2007. During the final editing process, the authors also retreated from many of the more confident projections from the final draft, leaked last year. The IPCC now says it often cannot predict which specific impacts of climate change such as drough
5、ts, storms or floods will hit particular places. Instead, the IPCC focuses on how people can adapt in the face of uncertainty, arguing that we must become resilient against diverse changes in the climate. “The natural human tendency is to want things to be clear and simple,“ says the reports co-chai
6、r Chris Field of the Carnegie Institution for Science in Stanford, California. “And one of the messages that doesnt just come from the IPCC, it comes from history, is that the future doesnt ever turn out the way you think it will be.“ That means, Field adds, that “being prepared for a wide range of
7、possible futures is just always smart“. Here New Scientist breaks down what is new in the report, and what it means for humanitys efforts to cope with a changing climate. A companion article, “How climate change will affect where you live“, highlights some of the key impacts that different regions a
8、re facing. What has changed in the new IPCC report? In essence, the predictions are intentionally more vague. Much of the firmer language from the 2007 report about exactly what kind of weather to expect, and how changes will affect people, has been replaced with more cautious statements. The scale
9、and timing of many regional impacts, and even the form of some, now appear uncertain. For example, the 2007 report predicted that the intensity of cyclones over Asia would increase by 10 to 20 per cent. The new report makes no such claim. Similarly, the last report estimated that climate change woul
10、d force up to a quarter of a billion Africans into water shortage by the end of this decade. The new report avoids using such firm numbers. The report has even watered down many of the more confident predictions that appeared in the leaked drafts. References to “hundreds of millions“ of people being
11、 affected by rising sea levels have been removed from the summary, as have statements about the impact of warmer temperatures on crops. “I think its gone back a bit,“ says Jean Palutikof of Griffith University in Brisbane, Queensland, Australia, who worked on the 2007 report. “That may be a good thi
12、ng. In the fourth climate assessment we tried to do things that werent really possible and the fifth has sort of rebalanced the whole thing.“ So do we know less than we did before? Not really, says Andy Pitman of the University of New South Wales in Sydney, Australia. It is just more rigorous langua
13、ge. “Pointing to the sign of the change, rather than the precise magnitude of the change, is scientifically more defensible,“ he says. We also know more about what we dont know, says David Karoly at the University of Melbourne. “There is now a better understanding of uncertainties in regional climat
14、e projections at decadal timescales.“ “If your system is vulnerable to the total amount of rainfall, I kind of think were getting to know that,“ says Pitman. “If however your system is vulnerable to the timing of rainfall, thats hard. If your system is vulnerable to the intensity of rainfall, that i
15、s very hard.“ Are we less confident about all the impacts of climate change? Not quite. There are still plenty of confident predictions of impacts in the report at least in the draft chapters that were leaked last year, and which are expected to be roughly the same when they are released later this
16、week. These include more rain in parts of Africa, more heatwaves in southern Europe, and more frequent droughts in Australia (see “How climate change will affect where you live“). It also remains clear that the seas are rising. How do we prepare in cases in which there is low confidence about the effects of climate change? Thats exactly what this report deals with. In many cases, the uncertainty is a matter of magnitude, so the choices are not hard. “It doesnt really matter
