The records show that an extreme drought that can last for many years or even a decade ้has severe impacts on the ecosystem. The five-year-long drought that hit the American West from 2000 to 2004 had profound consequences for carbon sequestration, agricultural productivity and water resources. Plants, for example, took in only half the carbon dioxide they normally do. In the drought's worst year, crop yields were down by 13 percent. Major river basins showed 5 percent to 50 percent reductions in flow.