Plugging natural gas leaks in polluted Eastern European and Asian cities could help reduce future warming of Earth's climate by the "greenhouse effect," according to a study published Thursday in the journal Nature.

"It would be one small step in the right direction - a manmade contributon to global warming that can be remedied by mankind's own efforts," said Stanley Tyler, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colo.The new study was published by chemists F. Sherwood Rowland, Donald Blake and Neil Harris at the University of California, Irvine.

"It's very significant work" because it shows one relatively easy way to reduce future global warming, said Kathleen Hogan of the U.S. Environmental Protection Agency's global change division.

"If we went in and found the leaks and fixed them in the natural gas systems in Eastern Europe and the Soviet Union, you'd have a very large start at reducing the contribution of methane to global warming," Hogan said.

Studies estimate up to 10 percent of Eastern Europe's natural gas leaks into the atmosphere because of poor transmission facilities.