Narrator: This is Science Today. For the past few years, environmental scientist John Harte of the University of California, Berkeley has been conducting an unusual experiment.

Harte: Starting in 1990 we've been warming a sub-alpine meadow in the Colorado Rockies with overhead electric heaters.

Narrator: Harte has been trying to find out the effect global warming will have on mountain ecosystems. Besides noting a change in vegetation, Harte discovered that heated soil releases lots of carbon dioxide. Excess carbon dioxide from burning fossil fuel seems to be causing global warming in the first place, according to Harte. So as the earth heats up, the soil will release even more CO2, causing a feedback loop leading to even more warming.

Harte: It points to the need to put more realistic ecological information into our climate models.

Narrator: Harte's results haven't yet been figured into predictions of global warming.

Harte: If you put them in, it suggests that the warming may be much greater than we think.

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