An international committee of hundreds of top scientists issued a gloomy forecast this morning of how human beings and natural ecosystems will fare in the future, as the effects of global warming intensify. The Intergovernmental Panel on Climate Change, an arm of the United Nations, said that warming over the past 30 years had already caused noticeable increases in heat-wave deaths, forest fires, and water shortages in many areas. While some regions, such as much of the United States, will see greater crop yields in the next few decades with modest increases in temperatures, other regions, such as the American Southwest, Africa, and much of Asia, could expect significant agricultural declines.

As the warming continues, all regions will suffer, concluded the panel in a summary report prepared for policy makers. Today’s report follows up on one, issued by the panel in February, that concluded that global warming is a reality, and that greenhouse-gas pollution is largely to blame. —Richard Monastersky