On 2/20/07, anand anand <[EMAIL PROTECTED]> wrote: > > The 2nd of February 2007 will one day hopefully be remembered as the day > the question mark was removed from the debate on whether human activities > are driving climate change, said the head of the UN Environment Programme at > the launch of the most authoritative scientific report on climate change to > date. > > The new Intergovernmental Panel on Climate Change report says there is 90% > certainty that the burning of fossil fuels and other human activities are > driving climate change. Read the global reaction to the report > here.<http://environment.newscientist.com/article/dn11096> > > "The word unequivocal is the key message of this report," said Achim > Steiner, executive director of UNEP, adding that those who have doubts about > the role of humans in driving the climate "can no longer ignore the > evidence". > > The IPCC report says the rise in global temperatures could be as high as > 6.4°C by 2100. The report also predicts sea level rises and increases in > the intensity of hurricanes. It is the work of 1200 climate experts from 40 > countries, who have spent six years reviewing all the available climate > research. It was released in Paris, France, on Friday (read the 21-page > summary here, pdf > format<http://media.newscientist.com/data/images/ns/av/dn11088D1.pdf>). > Listen to audio from today's press > conference<http://www.empreinte.com/richmediaevent/20070202/vod/ipc_audio_en_900x540_WindowsLD.htm> > . > > The last IPCC > report<http://www.newscientist.com/article/dn443-global-warning.html>, > issued in 2001, predicted that temperatures would rise by 1.4°C to 5.8°Cby > 2100, relative to 1990 temperatures. > > But the new report says temperature rises by 2100 could, in the most > extreme scenarios, range from 1.1°C and 6.4°C. The most likely range is > 1.8°C to 4.0°C (see figure 1, right), with the report predicting that 4°C > is most likely if the world continues to burn fossil-fuels at the same rate > (read the *The impacts of rising global > temperatures*<http://environment.newscientist.com/channel/earth/dn11089-the-impacts-of-rising-global-temperatures.html>). > > Melting, moving ice > > Rises in sea levels are predicted by the new report, threatening low-lying > areas of land around the world. As the oceans warm, their waters expand, > while rising temperatures also increase the melting of the ice sheets that > cover Greenland and Antarctica. > > In 2001, the IPCC predicted that sea levels would rise by between 9 and 88 > centimetres by 2100, relative to 1990 levels. The new report says rises > could range from 18 cm to 59 cm. The top end of the range corresponds to a > fossil-fuel intensive future (see A1F1 scenario in *Modelling the future > climate: the baseline > scenarios*<http://environment.newscientist.com/channel/earth/dn11090-modelling-the-future-climate-the-baseline-scenarios.html>). > > > But predictions of sea level rise are one of the most contentious areas of > the report - very recent research has suggested that rises of up to 140 cm > are possible (see *Shorelines may be in greater peril than > thought*<http://environment.newscientist.com/channel/earth/dn10799-shorelines-may-be-in-greater-peril-than-thought.html>). > > > The problem is that the understanding of how warming affects Greenland and > Antarctic ice sheets remains limited, and they are predicted to be the most > important contributors to change. Estimates of the straightforward melting > of ice are incorporated in the IPCC report. But warming may also accelerate > the movement of ice in glaciers into the ocean, perhaps by meltwater > lubricating the undersides of ice streams. > > Susan Solomon, one of the report's lead authors, said there was no > published research that quantified this effect, and so it was not included. > But she added: "If temperatures exceed 1.9°C to 4.6°C above pre-industrial > temperatures, and were to be sustained for thousands of years, eventually we > would expect the Greenland ice sheet to melt. That would raise sea level by > 7 metres." > > Climate change is also expected to affect the frequency and strength of > tropical storms and hurricanes. The latest IPCC report says the activity of > tropical cyclones is "likely" to increase over the 21st century. It says > "likely" indicates a probability of more than 66%. This is a bolder > statement than the World Meteorology Organisation issued in > January<http://environment.newscientist.com/channel/earth/dn10796-global-warming-link-to-hurricanes-likely-but-unproven.html>. > > > Precipitation patterns will change too by 2100, according to IPCC > predictions (see figure 2, right). Mid- to high-latitude regions will see up > to 20% more rain and snow, while the tropical regions will see less. > Humans to blame > > Considering the human role in causing climate change, the IPCC report is > damning: "The understanding of [human] influences on climate has improved > since the [2001] report, leading to a very high confidence that human > activities" are responsible for most of the warming seen since 1950, says > the report's summary for policymakers. "Very high confidence" is described > as "at least a 9 out of 10 chance of being correct". > > Before the industrial revolution, human greenhouse gas emissions were > small, and the atmospheric concentration of carbon dioxide the main > greenhouse gas was about 280 parts per million (ppm). > > Thanks largely to the burning of fossil fuels and changes in land use, > such as agricultural exploitation and deforestation, the atmospheric > concentration of carbon dioxide reached 379 ppm in 2005, says the IPCC. > Gold standard > > The IPCC draws together the world's leading climate experts to review and > assess all available research, under the auspices of UN Environment > Programme and the World Meteorology Organization. > > The result of their assessment, which is done every five to six years, > establishes what is considered the gold standard of consensus on climate > change science. > > The latest IPCC report was written by hundreds of experts and reviewed by > hundreds more, from 113 countries. It is being released in stages during > 2007. The first chapter, released on Friday, deals with the scientific basis > for climate change. > > The next two parts of the IPCC's 2007 assessment, plus a synthesis, will > be released throughout the year. Part 2, dealing with the impacts of climate > change and our vulnerability to those impacts, will be released in April. > Part 3, to be released in May, deals with how we might mitigate these > impacts. > > *Climate Change - Want to know more about global warming the science, > impacts and political debate? Visit our continually updated special report > <http://www.newscientist.com/channel/earth/climate-change>*. >
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