James Hansen of NASA is the only climatologist to have told Congress that the greenhouse effect is already here. He is a respected scientist but on this point very few of his colleagues agree with him, as Richard Kerr noted recently in Science. The Office of Management and Budget drew criticism when it heavy-handedly made Mr. Hansen qualify testimony to Congress last month. But its caveat, that his warnings ”should be viewed as estimates from evolving computer models and not as reliable predictions,” was scientifically impeccable. The computer models of the greenhouse effect are indeed ”evolving” -they’re somewhere around the amoeba stage.

Environmental lobbyists are tempted to emphasize the threat of the greenhouse effect because it reinforces so much of their other agenda.

The Editorial Notebook – Crying Wolf in the Greenhouse – NYTimes.com