James Hansen told Congress on Monday June 23, 2008 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 is particularly critical of coal fired power plants. Until carbon capture technology is able to remove and sequester the carbon in exhaust gasses, coal fied power plants remain the most concentrated source of CO₂ emmissions to the atmosphere.