Man vs. Nature

The planet grows warmer, and some scientists continue to debate.

ByABC News
October 19, 2007, 10:49 AM

Oct. 19, 2007 — -- The globe is warming, it's our fault and the consequences are going to be terrible. So goes the rhetoric spouted by politicians, celebrities and the media.

It's hard to turn on the TV or open a newspaper these days without hearing about the horrors caused by our warming climate. We can expect more floods, droughts, hurricanes and tornadoes as global warming continues, and pretty soon we'll have to flee from the coasts as the polar ice caps melt and our shorelines flood.

Children are frightened, too. I spoke to a group of kids who said they worry about their future on our planet. One girl feared that water might rise near her house in Rockaway, N.Y., "and it might flood the whole town."

A few of these kids learned about global warming from former Vice President Al Gore's documentary, "An Inconvenient Truth." The movie has been seen by millions, won an an Academy Award and earned Gore widespread praise in the media. People have proclaimed him a "prophet," a "cultural icon" and a "conquering hero." Just last week, he won the Nobel Peace Prize. With all this news coverage, it's no surprise that 86 percent of Americans think global warming is a serious problem and 70 percent want the government to do something now.

But is it a crisis? The globe is warming, but is it really all our fault? And is it true the debate is over? No. What you think you know may not be so.

In the movie, for example, Gore says that if we allow the globe to warm, "sea levels worldwide would go up 20 feet." Then he shows his audience terrifying maps of Florida and San Francisco submerged under rising sea levels. But the Intergovernmental Panel on Climate Change, which shared last week's Nobel Prize with Gore, said that would probably take thousands of years to happen. Over the next 100 years, sea levels are expected to rise seven to 24 inches, not 20 feet.

Gore also implies that polar bears are dying off, because receding Arctic ice has forced them to swim longer distances. The kids I interviewed were especially worried about the fate of the polar bears. But the polar bears appear to be doing all right. Future warming may hurt them, but right now data from the World Conservation Union and the U.S. Geological Survey show most populations of polar bears are stable or increasing.

The most impressive demonstration in Gore's movie is that big graph of temperature and carbon dioxide levels stretching back 650,000 years. Carbon dioxide is thought to amplify temperature increases, but his graph seemed to show clear cause and effect: When carbon dioxide levels rose, so did temperature. It suggested that carbon levels controlled temperature. But a real inconvenient truth is that the carbon increase came after temperatures rose, usually hundreds of years later. Temperature went up first.

I wanted to ask Gore about that and other things, but he wouldn't agree to an interview. According to Gore, the "debate is over."

I interviewed some scientists who say the debate is by no means over. John Christy and Roy Spencer won NASA's Medal for Exceptional Achievement for figuring out how to get temperature data from satellites.

"We all agree that it's warmed," Spencer said. "The big question is, and the thing we dispute is, is it because of mankind?"

Climate changes, they say, always has, with or without man. Early last century, even without today's huge output of carbon dioxide, the Arctic went through a warming period.

Greenland's temperatures rose 50 percent faster in the 1920s and reached higher average temperatures in the 1930s and 1940s than today's temperatures.

Some scientists argue the warming might be caused by changes in the sun, or ocean currents, or changes in cloud cover, or other things we don't yet understand. The debate is not over.

But who's to say that yesterday's temperature is the perfect one?

"The fact is, when climate changes, there are gains and there are losses," said Tim Ball, who studies the history of climate change. But, he points out, all we generally hear about is the bad news from the IPCC that massive group of climate scientists.

Paul Reiter of the Pasteur Institute participated in one of the IPCC drafts and Christy was a contributing author. Both say that this Nobel Prize-winning group is not what people think it is.