US/World

Cold Winters May be Caused by Warmer Summers: Study

Winter Central Park
Creative Commons Tais Melillo

A new study suggests that the increasingly cold winters over the past two decades could be due to warmer temperatures in the autumn, changing normal weather patterns and causing temperatures to plummet in the winter.

The findings come after extremely cold winters experienced in the Northern Hemisphere and amid increasing temperatures and melting ice in Arctic regions, creating more snowfall in the autumn months at lower latitudes.

The study’s authors’ say the warmer weather allows the Arctic atmosphere to hold more moisture, which increases the likelihood precipitation over southern areas, which, in freezing temperatures falls as snow.

Researchers from the Atmospheric and Environmental Research (AER), the University of Massachusetts and the University of Alaska Fairbanks, said that the strongest winter cooling trends, observed in the eastern United States, southern Canada and much of northern Eurasia, “cannot be entirely explained by the natural variability of the climate system.”

Study results shows strong increases in temperature in the Arctic during the months of July, August, and September that continued through the autumn, which appeared to enhance the melting of the Arctic sea ice.

The study showed that Eurasia has increased in snow fall over the past two decades.

Researchers suggest that increased snow fall has a complicated effect on the Arctic Oscillation, an atmospheric pressure pattern in the mid to high latitudes, which causes it to remain in the "negative phase".

The authors explained that in the "negative phase", high pressure resides over the Arctic region, pushing colder air into mid-latitude regions, such as the United States and northern Canada, and giving the observed colder winters.

"In my mind there is no doubt that the globe is getting warmer and this will favor warmer temperatures in all seasons and in all locations,” said Judah Cohen, lead author of the study published in the journal Environmental Research Letters.

“However, I do think that the increasing trend in snow cover has led to regional cooling as discussed in the paper and I see no reason why this won't continue into the near future. Also if it continues to get much warmer in the fall, precipitation that currently falls as snow will fall as rain instead, eliminating the winter cooling."

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