Is carbon dioxide the key to global warming?

Scientists at a remote research station on the high desert of eastern Oregon could be uncovering some of the answers as to what might be causing global warming. Rangelands, including grasslands, cover about half of the Earth's land area and account for a third of all plant life. However, not much is known about how they fit into the global climate change puzzle, notes Tony Svejcar, a scientist at the Eastern Oregon Agricultural Research Center, Bums. Oregon State University, Corvallis, and the U.S. Department of Agriculture's Agricultural Research Service (ARS) operate the isolated research center.

"The role of oceans and forests in the global carbon cycle has been studied, but rangelands have received relatively tittle attention," he points out. "Scientists have been unable to account for a substantial amount of the Earth's carbon. Rangelands (including grasslands) may hold the key."

There seems to be an increasing amount of carbon dioxide in the atmosphere, due in part to a growing world population that burns fossil fuels. Researchers don't know exactly what this means in terms of long-term climate change, but many believe the atmosphere is warming. There also are suggestions that the world's climate may change as a result of increasing [CO.sub.2], whether there is significant warming or not. The timing of precipitation is one of the climate factors that could become different.

Svejcar and other scientists are taking part in a national attempt to learn more about the rangeland-carbon dioxide relationship and how precipitation timing affects plant life on rangelands. Their experiments involve space-age instrumentation and sheds that resemble picnic pavilions.

A device called the Bowen ratio-energy balance unit has digital readout and solar power panels. "It measures the difference between the carbon dioxide content of the air at two different levels--one just above the plants and the other about three feet above the canopy [of rangeland plants]," explains ARS scientist Raymond Angell. "It can detect concentration changes as small as one part per million. This, in turn, can tell us...