CNN - Messing with the thermostat can be devastating


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Causes of Global Warming

Messing with the thermostat can be devastating

November 27, 1997

From Correspondent Miles O'Brien

(CNN) -- If you want to learn about climate change, ask oceanographer Sylvia Earle.

Twenty miles off the coast of Georgia, she has seen the fossilized evidence that mastodons and humans lived here 10,000 years ago.

"Clearly, sea level goes up and sea level goes down," she says. "There are natural cycles."

Think of those cycles this way: Consider the Earth to be wrapped in a blanket -- in this case, a blanket of gases. Among the ingredients are water vapor, carbon dioxide and methane.

This blanket insulates the Earth by trapping heat, a lot like panes of glass in a greenhouse.

Top greenhouse gas emitters (in percentages)

"It is part of what makes the planet work," Earle says. "Plants and human beings and animals generally produce carbon dioxide as part of the living process. Methane is a natural gas, and it is produced by the natural system."

Indeed, gaseous emissions from livestock are a major source of methane.

Without greenhouse gases, the Earth would be much too cold for comfort, unable to sustain life as we know it. But the problem now is that humans are thickening the blanket by producing a lot of greenhouse gases by burning fossil fuels. As a result, more heat is trapped -- and, scientists say, nature's thermostat is nudged up.

Factoids

The 10 warmest years on record (since the 1880s) have taken place in the last 15 years.

The family of greenhouse gases includes carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons, hydrofluorocarbons and perfluorinated carbons.

Carbon dioxide is believed to be responsible for 70% of global warming.

Source: Union of Concerned Scientists

"It is like pushing the fast forward button -- speeding up the process, accelerating what may be part of the natural process," Earle says.

The planet is littered with proof that pushing the fast forward button on the climate machine can mean big trouble. Sixty-five million years ago, scientists believe, an asteroid augered into what is now Mexico, kicking up the mother of all dust storms. The sun's rays were blocked. Plants and trees died en masse. And it was soon curtains for the dinosaurs.

Ironically, though, that laid the groundwork for the climate troubles we're having today. When the dust settled, mammals -- and ultimately humans -- had a clear path to dominate the planet.

We invented the sport utility vehicle, while the dinosaurs quietly decomposed into fossil fuels, eventually becoming unleaded gasoline.

While doomsayers aren't predicting that we are headed the way of the dinosaurs, they do have some sobering forecasts.

"Suppose over the next hundred years, you have a rise of sea level, as some are saying, of two or three feet," Earle says. "The consequences of places such as Florida would be rather dramatic, both ecologically and economically."

Indeed, some island nations may virtually disappear. Forests will feel the squeeze because many trees cannot adapt fast enough to keep up with rising temperatures.

Fall in New England could lose its vivid hues. More important would be the impact on human health. Heat-related deaths may rise, and tropical diseases, such as malaria, could spread.

It's a bleak outlook, and Earle believes we must do something to avoid it.

"This is a pivotal time in history, and I think as such we should take the responsibility pretty seriously and look at what we can do," she says.