Tuesday, 1 September 2015

Climate change in the United States North-East

Here’s Why the Northeast’s Next Winter Is Going to Be Freakishly Cold
New research shows that vanishing Arctic summer sea ice—a consequence of global warming—may drive extreme winters in lower latitudes for decades to come.



31 August, 2015


When it comes to the global climate, what happens in the Arctic does not stay in the Arctic. The latest proof comes in new research connecting the unusually brutal winter of 2014–15 along the East Coast of North America to rapidly vanishing summer sea ice on the western side of the Arctic Ocean.

The new study, published Monday in the journal Nature Geoscience, advances a growing body of science demonstrating that these record-breaking extremes have not been a pause in the advance of human-driven climate change but a result of it.

The findings suggest that as the Arctic continues to thaw, the mercury will crash over many winters to come.

Temperatures reached record lows across the Northeastern United States last winter, with towns and cities in states from Maine to Maryland registering their coldest temperature averages from January to March.

Among the region’s weather extremes, parts of Buffalo in upstate New York disappeared under more than 100 inches of snow in November, before winter had even formally commenced. Snow fell for 23 straight days during February in Syracuse, another upstate New York city.

Boston’s total of 108.6 inches of snow for the season broke a 17-year record and crippled the city. To the south, ocean waves along the Cape Cod, Massachusetts, shoreline grew so cold and thick with icy slush that they froze in place for weeks.


The newly published study, led by Jong-Seong Kug of South Korea’s Pohang University of Science and Technology, used climate and weather observations as well as climate change modeling to investigate potential connections between these and other extreme cold winter weather systems over North America and South Asia last winter and historically low levels of summer sea ice in areas of the Arctic Ocean.

Kug and his colleagues determined that the reduced extent of summer sea ice in the Beaufort and Chukchi seas during the summer of 2014 led to a bulge of warmer temperatures in the lower atmosphere.

Those warm-temperature areas are “an indication that the jet stream is taking a big northward swing, creating what we call a very strong ridge,” said Jennifer Francis, an atmospheric scientist at Rutgers University who studies Arctic ice and its effects on weather patterns in lower latitudes of the northern hemisphere.

Downstream of that ridge, the effect is like taking a jump rope and giving it a big whip: It creates a big wave further downstream, a southward dip in the jet stream,” Francis said. “That means that cold air is able to plunge down into that area from the Arctic, and that’s been contributing to these very cold winters in eastern North America.”

The same conditions also formed high above the Barents and Kara seas, on the Atlantic side of the Arctic Ocean, and drove severe cold weather in South Asia during the winter.

Kug’s work has advanced understanding of the mechanisms that link Arctic warming to changes in weather in lower latitudes, Francis said, adding that the knowledge could help residents and governments in these regions better prepare for severe winters to come. However, once the Arctic Ocean becomes completely ice-free in summer, which scientists expect to happen in the next 25 to 35 years, weather patterns are likely to shift again in ways that are impossible to anticipate.

The extent of summer sea ice in the Beaufort and Chukchi seas has been tracking below 2010, 2013, and 2014 levels since mid-August—three years that each went on to see significantly colder, snowy winters in the Northeast—according to the U.S. National Snow and Ice Data Center.

On Aug. 16, the NSIDC reported, ice covered 2.24 million square miles on the two seas—521,200 square miles below the 1981–2010 average and 451,700 square miles above the level on the same date in 2012, which holds the record for the lowest recorded summer sea ice extent.



On Aug. 16, sea ice area on the Chukchi and Beaufort seas, in the Arctic Ocean, was tracking below ice extents on the same day in 2010, 2014, and 2014, as well as the 19-year average. It had not dipped below the record-setting low ice extent of 2012. (Image: National Snow and Ice Data Center)

Arctic sea ice will continue to melt until early to mid-September.


There is so much disturbing evidence coming out these days about the impacts of increasing fossil fuel burning and other human-caused climate change,” said Francis. “It’s hard to imagine that anyone can just snub their noses at it and say ‘Things are fine—we don’t have to do anything.’ ”


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