the United States. What could be more basic than that? NARRATOR: From the wealth of nations to the future of the planet: Are humans warming the globe? Or are we an insignificant influence compared with the natural forces which have determined the climate for millions of years? JAMES TREFIL, George Mason University: If you sat down and said, "I'm going to design a public issue that is the absolute worst nightmare of every scientist, of every communicator in the world," you couldn't do better than the greenhouse effect. You're dealing with something that's very complicated. You're dealing with something where there's legitimate uncertainty in the science. It's not that people are trying to pull the wool over anybody's eyes. There's legitimate uncertainty. You're dealing with something that has enormous consequences for people. And you're dealing with something whose effects will happen 30 years down the road, you know, when they happen. And then you say- you give people this and say, "Okay, do something about it." TOM BROKAW, NBC News: It is, in fact, a heat wave of global and historic proportions, more than- NARRATOR: The issue is typically framed in the media as a simple question: Is it getting warmer? DAN RATHER, CBS News: Final figures in from Canada today show October '98, was the warmest October on Earth on record. JAMES TREFIL: Unfortunately, when people talk about global warming, it's always in terms of, "Oh, gosh, it was hot last summer." And that doesn't work because weather and