Scorching current heat waves "virtually impossible" without climate change, researchers say

The fingerprints of climate change are all over the intense heat waves gripping the globe this month, a new study finds. Researchers say the deadly hot spells in the American Southwest and Southern Europe couldn't have happened without the continuing buildup of warming gases in the air.

These unusually strong heat waves are becoming more common, Tuesday's study said. The same research found the increase in heat-trapping gases, largely from the burning of coal, oil and natural gas has made another heat wave - the one in China - 50 times more likely and with the potential to occur every five years or so.

A stagnant atmosphere, warmed by carbon dioxide and other gases, also made the European heat wave 4.5 degrees hotter, the one in the United States and Mexico 3.6 degrees warmer and the one in China 1.8 degrees toastier, the study found.