Earth Hotter Than It's Been in 400 Years

says panel of top climatologists in report to Congress from the National Academy of Sciences.

Bush administration response? "Pffft."

WASHINGTON (AP) -- The Earth is the hottest it has been in at least 400 years, probably even longer. ...

A panel of top climate scientists told lawmakers that the Earth is running a fever 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. ...

The Bush administration also has maintained that the threat is not severe enough to warrant new pollution controls ...

Overall, the panel agreed that the warming in the last few decades of the 20th century was unprecedented over the last 1,000 years, though relatively warm conditions persisted around the year 1000, followed by a "Little Ice Age" from about 1500 to 1850. ...

[T]here were sharp spikes in carbon dioxide and methane, the two major "greenhouse" gases blamed for trapping heat in the atmosphere, beginning in the 20th century, after remaining fairly level for 12,000 years.