Representatives at a climate conference at the Hague this week are trying to agree on how to cut down on pollutants that are believed to cause global warming. One of the main pollutants is carbon dioxide. The United States supports what its calls a flexible plan. In part, that means forests that absorb carbon would count toward meeting reduction targets. There has even been talk of paying farmers here in the United States to plant trees rather than crops. The European Union rejected the United States' plan yesterday. John Pastor is a biology professor and part of the University of Minnesota's Natural Resources Research Institute in Duluth. He's on the line now. John Pastor is a biology professor at the University of Minnesota-Duluth