June 24, Yahoo

WASHINGTON - Exactly 20 years after warning America about global warming, a top NASA scientist said the situation has gotten so bad that the world's only hope is drastic action.

James Hansen told Congress on Monday that the world has long passed the "dangerous level" for greenhouse gases in the atmosphere and needs to get back to 1988 levels. He said Earth's atmosphere can only stay this loaded with man-made carbon dioxide for a couple more decades without changes such as mass extinction, ecosystem collapse and dramatic sea level rises.

"We're toast if we don't get on a very different path," Hansen, director of the Goddard Institute of Space Sciences who is sometimes called the godfather of global warming science, told The Associated Press. "This is the last chance."

Hansen brought global warming home to the public in June 1988 during a Washington heat wave, telling a Senate hearing that global warming was already here. To mark the anniversary, he testified before the House Select Committee on Energy Independence and Global Warming where he was called a prophet, and addressed a luncheon at the National Press Club where he was called a hero by former Sen. Tim Wirth, D-Colo., who headed the 1988 hearing.

To cut emissions, Hansen said coal-fired power plants that don't capture carbon dioxide emissions shouldn't be used in the United States after 2025, and should be eliminated in the rest of the world by 2030. That carbon capture technology is still being developed and not yet cost efficient for power plants.

Burning fossil fuels like coal is the chief cause of man-made greenhouse gases. Hansen said the Earth's atmosphere has got to get back to a level of 350 parts of carbon dioxide per million. Last month, it was 10 percent higher: 386.7 parts per million.

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photo: Jim Hansen, left, a leading researcher on global warming, talks with House Select Energy Independence and Global Warming Committee Chairman Rep. Edward Markey, D-Mass., right, prior to a briefing on global warming on Capitol Hill in Washington, Monday, June 23, 2008 (AP Photo/Susan Walsh)