Earth's temp at 400-year high

A panel of top climate scientists told lawmakers that the Earth is heating up and that "human activities are responsible for much of the recent warming." Their 155-page report said average global surface temperatures in the Northern Hemisphere rose about 1 degree during the 20th century.

This is shown in boreholes, retreating glaciers and other evidence found in nature, said Gerald North, a geosciences professor at Texas A&M University who chaired the academy's panel.

The report was requested in November by the chairman of the House Science Committee, Rep. Sherwood Boehler, R-NY, to address naysayers who question whether global warming is a major threat.

Last year, when the House Energy and Commerce Committee chairman, Rep. Joe Barton, R-Texas, launched an investigation of three climate scientists, Boehlert said Barton should try to learn from scientists, not intimidate them.

Boehlert said Thursday the report shows the value of having scientists advise Congress.

"There is nothing in this report that should raise any doubts about the broad scientific consensus on global climate change," he said.

Other new research Thursday showed that global warming produced about half of the extra hurricane-fueled warmth in the North Atlantic in 2005, and natural cycles were a minor factor, according to Kevin Trenberth and Dennis Shea of the Commerce Department's National Center for Atmospheric Research. Their study is being published by the American Geophysical Union.

The Bush administration has maintained that the threat is not severe enough to warrant new pollution controls that the White House says would have cost 5 million Americans their jobs.