Narrator: This is Science Today. The world seems to be getting warmer. Environmental scientists like John Harte of the University of California, Berkeley believe the so-called greenhouse effect is caused by increased carbon dioxide in the atmosphere, mostly released by humans.

Harte: The major cause of net increase in atmospheric CO2 is fossil fuel burning. Secondarily, it's deforestation.

Narrator: To find out how the greenhouse effect will change local ecosystems, Harte put heat lamps over a Rocky Mountain meadow for several years. He discovered that as the temperature goes up, the soil releases carbon into the atmosphere.

Harte: And since a huge amount of carbon is locked up in soil, the potential is there for a large release.

Narrator: Which could mean the start of a global feedback loop, where more carbon leads to higher temperatures, in turn releasing more carbon, raising temperatures even faster than scientists currently predict.

Harte: The ecosystem response could almost double the rate at which the atmosphere CO2 level goes up.

Narrator: For Science Today, I'm Steve Tokar.