Scientists at UC San Diego's Scripps Institution of Oceanography are joining forces with two federal laboratories run by the University of California for a major study of how human interference is changing the Earth's climates. Using supercomputers at UC San Diego and Los Alamos and Lawrence Livermore national laboratories, the researchers will try to answer fundamental questions about how the oceans and the atmosphere interact to maintain the planet. The knowledge the four-year effort will seek is essential to determining, for instance, how fast world temperatures will rise because of the "greenhouse effect." Scientists now suspect this byproduct of the buildup of carbon dioxide in the atmosphere could raise average annual temperatures within the next few decades to levels not experienced in more than 100,000 years. In June, scientists told Congress they thought the U.S. drought that was scorching crops in the nation's Farm Belt could be attributed to the effect.