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Today is an extremely unusual December day at the North Pole, with temperatures getting very close to the melting point of 32 degrees Fahrenheit, or 0 degrees Celsius.。

For perspective, the temperature at the North Pole is about 40 degrees Fahrenheit above average for the date.
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Data from a buoy located about 80 miles south of the dark, windswept pole hit 32 degrees on Thursday morning as storm systems dragged unusually mild air into the high Arctic. Aiding the warm spell is the fact that these winds passed over Arctic waters that would normally be covered with sea ice but are open ocean this year after a severe sea ice melt season and record-slow winter freeze-up.。

SEE ALSO:North Pole to warm to near melting point this week: 50 degrees above normal 。

The bizarre Arctic heat wave, which will be brief, lasting only two days, is similar to another warmup that occurred in December 2015, and there is scientific evidence showing that these extreme events are becoming more frequent and extreme in the Arctic as sea ice melts and air temperatures increase.。

However, the mean temperatures in the Arctic this fall into early winter, including the spike this week, have no precedent in the records kept since 1958 by the Danish Meteorological Institute. Though sharp oscillations in temperature have happened throughout the record, the mean temperatures are much higher this year. It's as if the Arctic has shifted into a new, higher gear of climate change.。

The roots of this week's event can be traced to multiple storm systems curling northwest out of the Atlantic side of the Arctic, passing to the northeast of Greenland. These cyclones set up a southeasterly airflow that moved moist and relatively mild (mild for the Arctic anyway) air across the Barents Sea.。

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Air pressure (top), and air temperatures (bottom in red, arrow pointing to Dec. 22) from the buoy near the North Pole.Credit: International arctic buoy program  。

That's important since this region has unusually low amounts of sea ice. This makes that area an ideal source region, or heat reservoir, for relatively warm air to be picked up and transported closer to the pole.。

In the summer and fall, low sea ice cover allows ocean waters to absorb heat from the sun, which is then slowly released into the air in the fall and early winter. Ice-covered areas stay cooler since sea ice reflects most incoming solar radiation.。

A buoy ~140km from the North Pole right up to freezing Thursday morning!

A buoy ~140km from the North Pole right up to freezing Thursday morning! #arctic #seaice climatologist49 ZLabe DaveSnider pic.twitter.com/mmJHgJ3DSW。

— Rick Thoman (AlaskaWx) December 22, 2016。

This warmup is taking place amid the Arctic's warmest year since records began in 1900, according to an international scientific assessment released on Dec. 13. A persistent pattern of anomalously warm conditions across the central Arctic, including the North Pole, has set up this fall and winter, partly in response to the second-lowest sea ice minimum reached in September. 

The warm air intrusion into the Arctic has actually eaten away at some of the fledgling sea ice cover, causing about 57,000 square miles of ice to be lost between Dec. 21 and Dec. 22, according to preliminary data from the National Snow and Ice Data Center. While that figure is likely to change somewhat as scientists double check it during quality control, it amounts to the size of Iowa. This is significant, since the ice should be growing right now.。

GFS computer model simulation of temperature departures from average, with the high anomalies near the North Pole circled.Credit: tropicaltidbits.com。 An analysis published Wednesday by scientists affiliated with the research and journalism group Climate Central found that the record warm November and December in the Arctic would have been "extremely unlikely" in a world without human-caused global warming. A separate study, published this year in the
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Journal of Climate。

this year, found that there is an increase in the number of these events, known as "moist intrusions," crossing 70 degrees north Latitude in December and January. The research found that the number of these events during December and January has nearly doubled since 1990, but it did not explain why this is the case.。

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These events are not without significant consequences, since when they affect land they can cause rain to fall on top of snow and ice cover, forming a crust that prevents animals like reindeer from accessing their food supplies below.。

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One rain on snow event, associated with a sudden warming in the Arctic, killed about 61,000 reindeer on the Yamal Peninsula in 2013, demonstrating the ecological consequences of such freak heat episodes. 

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