科学美国人60秒:Blame Heat Waves on Loss of Arctic Sea Ice

In the summer of 2012, the U.S. baked. From the end of June through July, temperature records were set across the middle of the country. Drought partnered with the heat to cause discomfort for individuals and misery for farmers. And the cause may have been the record-setting meltdown of Arctic sea ice. That's according to a new paper in the journal Nature Climate Change.

The loss of sea ice leads to a weakening of winds high in the atmosphere. The reduced temperature difference between the Arctic and lower latitudes diminishes the jet stream as well. It also moves the jet stream north, letting hot air sit longer.

Such a lessening of the jet stream may have been responsible for Hurricane Sandy turning ashore and wreaking havoc in New York City and New Jersey. And the phenomenon extends beyond North America. Weak jet streams have prolonged heat waves in Russia as well as parked downpours over Europe.

One thing's for sure: increasing concentrations of greenhouse gases in the atmosphere will continue to warm the Arctic and melt ice and snow. And that could mean much hotter summers across the northern hemisphere.

—David Biello

[Scientific American is part of Nature Publishing Group.]