‘Smoking gun’ for human-caused warming

Raising the temperature
The world’s global average temperature has risen about 1.2 degrees Fahrenheit from 1901 to 2005. The two warmest years on record for the world were 2005 and 1998. Last year was the hottest year on record for the United States.The report will draw on already published peer-review science.

Some recent scientific studies show that temperatures are the hottest in thousands of years, especially during the last 30 years; ice sheets in Greenland in the past couple years have shown a dramatic melting; and sea levels are rising and doing so at a faster rate in the past decade.

Also, the second part of the international climate panel’s report — to be released in April — will for the first time feature a blockbuster chapter on how global warming is already changing health, species, engineering and food production, said NASA scientist Cynthia Rosenzweig, author of that chapter.

More computer models
As confident as scientists are about the global warming effects that they’ve already documented, they are as gloomy about the future and even hotter weather and higher sea level rises. Predictions for the future of global warming in the report are based on 19 computer models, about twice as many as in the past, Solomon said.

In 2001, the panel said the world’s average temperature would increase somewhere between 2.5 and 10.4 degrees Fahrenheit and the sea level would rise between 4 and 35 inches by the year 2100.

The 2007 report will likely have a smaller range of numbers for both predictions largely because of improvements in the climate models, Pachauri and other scientists said.

"I think probably the low value (in the 2001 report) and also the high value came from models that probably had mistakes in them," Trenberth recently told the Rocky Mountain News of Denver. "The confidence in those numbers was probably not that good, and they probably never should have been used in the way in which they were used."

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