Scientists have long predicted that global warming will worsen heat waves and torrential rainfalls. In some parts of the world, that is exactly what happened last year, climate scientists reported Thursday.

Rising temperatures add energy to the atmosphere, and computer models warn that this will produce wider and wilder swings in temperature and rainfall and alter prevailing wind patterns. In examining a dozen extreme weather events last year, scientists found that evidence that human activity — in particular, emissions of heat-trapping carbon dioxide from the burning of fossil fuels — was a partial culprit in about half of them.

Yet other extreme weather events, including the drought that withered the Midwest, appear to be just part of a natural pattern, the scientists concluded. The research, a series of 19 studies by 18 teams, was published in a special issue of the Bulletin of the American Meteorological Society.

While global warming will likely increase the number and severity of extreme weather events, climate scientists have been reluctant to attribute a particular heat wave, storm or drought directly to global warming, because of the natural variations of weather. But with advances in computer modeling and analysis of climate data, they are now able to tease out the contributions of human civilization.