美国国家公共电台 NPR Arctic's Temperature Continues To Run Hot, Latest 'Report Card' Shows（在线收听）

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The Arctic is a huge icy cap on the planet, and it acts like a global air conditioner. But the air conditioner is breaking down. Today, scientists issued a grim report card on the Arctic. They say the pole continues to warm at an alarming pace. And as NPR's Christopher Joyce reports, that will change our weather.

CHRISTOPHER JOYCE, BYLINE: The Arctic is a vast circle of frozen land with the Arctic sea like a giant icy pond in the middle but not as icy as it used to be. This was the second warmest year there in at least 1,500 years. The warmest ever - last year. This year also saw the least amount of winter ice in the Arctic Ocean ever observed, and ocean water was several degrees warmer than just a few decades ago. It's a trend that some are calling the new normal. Arctic scientist Jeremy Mathis says there's nothing normal about it.

JEREMY MATHIS: There is no normal. That's what's so strange about what's happening in the Arctic, is that the environment is changing so quickly in such a short amount of time that we can't quite get a handle on what this new state is going to look like.

JOYCE: Mathis runs the Arctic Research Program at the National Oceanic and Atmospheric Administration. He says changes in the Arctic are going to affect everybody in the Northern Hemisphere. Here's why. Masses of air and ocean currents circulate between a cold Arctic and the warmer parts of the hemisphere sort of like a conveyor belt. It's driven largely by the temperature difference or gradient between the two regions. But with less snow and ice to reflect the sun's rays, the Arctic isn't so cool anymore.

MATHIS: The heat is not being reflected back into space. The heat is now being absorbed into the land and into the ocean.

JOYCE: And that's going to alter things like the jet stream or rainstorms.

MATHIS: Whether they be wildfires out in California or hurricanes down in the Gulf, we have to think about the impacts that the changes in the Arctic are having on those disruptive climate events.

JOYCE: Scientists say they can't attribute any particular drought or hurricane to changes in the Arctic, but computer simulations do show changes to things like the wind.

KRISTOPHER KARNAUSKAS: And we're talking about a reduction of wind power all the way across the Northern Hemisphere midlatitude.

JOYCE: That's Kristopher Karnauskas, an atmospheric scientist at the University of Colorado. He says average wind speed in many places could drop by the end of the century, which he says could put a damper on wind energy.

KARNAUSKAS: For example, in the central United States, the models are predicting somewhere between 10 and 40 percent reduction in - compared to present-day amount of wind power.

JOYCE: Karnauskas notes that lots of other weather phenomena affect wind besides what happens at the pole. But the Arctic is a big player.

KARNAUSKAS: We live in between the Arctic and the equator. And those are, like, the two ends of the global energy machine, the weather machine.

JOYCE: And there's more. A warmer Arctic could cause more drought in California. Atmospheric researcher Ivana Cvijanovic also ran computer simulations of a warmer Arctic at the Lawrence Livermore National Laboratory where she works. She found that air circulation over the eastern Pacific could change in a way that would steer rain away from California.

IVANA CVIJANOVIC: So on average it will be 10 to 15 percent dryer.

JOYCE: Cvijanovic notes that other weather patterns outside the Arctic could counteract that drying effect. She says it's too early to blame the Arctic for California's recent drought. But she says the drought is a good illustration of what the future could bring. Christopher Joyce, NPR News.

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