Computer Simulation Shows Human Contribution to Global Warming

Scientists are reporting what one expert calls the clearest evidence yet that humans may be contributing to global warming and other changes in climate. In a study in the July 4 issue of Nature, British researchers used computer simulations to investigate the effects of buildup in carbon dioxide, production of tiny particles from the burning of coal and oil and depletion of high-altitude ozone by man-made chemicals.

They found that patterns of temperature change in the computer-simulated atmosphere resembled patterns observed in the real atmosphere from 1963 to 1987. One temperature pattern was cooling in the upper atmosphere and warming at lower altitudes, an apparent result of carbon dioxide buildup. The changes were too big to have come from natural variations in climate, they said.