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Extremely cold winter USA happens less often but may be linked to climate change

Warm Pacific may cause US winter freeze, study finds SMH, 24 May 14 Unusually warm western Pacific waters linked to global warming may be the paradoxical cause of a bone-chilling winter in parts of the United States this year, a scientific study said on Thursday.

The theory contrasts with other experts’ views, including that the freeze was simply a freak natural event or that it was linked to a thawing of the Arctic in recent years that sent a blast of cold air south.

“People’s reaction when they sit under 10 feet of snow is to say ‘this cannot be man-made climate change’,” said Professor Tim Palmer of Oxford University, who published his research in the journal Science. “But there is a plausible link,” he told Reuters.

He said a strengthening of trade winds had led to a build-up of warm water in the western tropical Pacific, aggravated in recent years by global warming from man-made emissions of greenhouse gases.

Thunderstorms linked to the warmth in turn disrupted the jetstream, high altitude winds which flow in vast meandering loops around the northern hemisphere, and sucked cold air from the Arctic. Detroit, for instance, suffered record snows and the coldest January since 1977.

Pinpointing the causes of the US chill, when climate change should make cold winters less likely, would help companies, farmers, city planners or even home owners wondering if they should invest in extra roof insulation.

Two other experts were unconvinced by Palmer’s study………

So far there is limited understanding of how weather in one part of the world can affect another.

Weather experts agree, however, that the El Nino weather phenomenon that mainly cools the eastern Pacific Ocean every few years can cause droughts or downpours on other continents.

Palmer told Reuters that his theory, building on a 1980s study he wrote suggesting a link between a chill 1976-77 US winter and a warm Pacific, could be tested because there are signs that an El Nino will form later this year.

An El Nino would also cool the western Pacific and that meant a cold US winter was less likely in 2014-15, he said.

A U.N. panel of climate scientists says it is at least 95 per cent probable that human activities, led by burning fossil fuels, are the main cause of warming since the 1950s, and will cause more heatwaves, floods and rising sea levels.  http://www.smh.com.au/environment/climate-change/warm-pacific-may-cause-us-winter-freeze-study-finds-20140523-zrlnj.html#ixzz32fmyw5TO

May 24, 2014 - Posted by Christina Macpherson | climate change