Climate researchers: Deadly Russian heat wave was natural

Global warming was not directly to blame for last summer's deadly — and extraordinary — heat wave in Russia, researchers said in a report Wednesday that came with a climate warning.

"We may be on the cusp of a period in which the probability of such events increases rapidly, due primarily to the influence of projected increases in greenhouse gas concentrations," said the team led by Randall Dole and Martin Hoerling of the U.S. National Oceanic and Atmospheric Administration.

It was the warmest July since at least 1880 in western Russia. The heat wave led to an increase in deaths in the region, as well as drought, widespread fires, increased air pollution and severe crop damage. Also affected by the warming were Belarus, Ukraine and the Baltic nations.