Climate Impacts Of Polar Low Arctic Hurricanes
December 17, 2012

Scientists Investigate Arctic Hurricanes’ Impact On Climate Models

redOrbit Staff & Wire Reports - Your Universe Online

The intense, small scale storms known as polar lows could have a tremendous impact on oceanic water circulation and climate predictions, a team of researchers from the US and UK have discovered.

According to scientists from the University of East Anglia (UEA) and the University of Massachusetts at Amherst, the storms, which are also known as Arctic hurricanes, contain areas of extremely low barometric pressure and can produce massive waves capable of sinking smaller ships. They are difficult to forecast, occur frequently and tend to be absent from most existing climate models.

However, in research published over the weekend in the journal Nature Geoscience, experts from the two universities report that these storms, with their hurricane-strength winds, could cause ocean waters to cool, resulting in changes in their circulation patterns.

Thousands of these storms occur annually, but as they are not accounted for in most prediction models, the researchers say it is difficult to determine what impact they could have on climate change in Europe and North America over the next several decades.

"Before polar lows were first seen by satellites, sailors frequently returned from the Arctic seas with stories of encounters with fierce storms that seemed to appear out of nowhere," Alan Condron, a geoscientist and physical oceanographer from the University of Massachusetts at Amherst, said in a statement on Sunday.

In order to better understand the impact of these Arctic hurricanes on climate change, Condron and his colleague, Professor Ian Renfrew of the UEA School of Environmental Sciences, began using a newer climate model in order to simulate the high-speed winds associated with these polar storms.

"By using higher resolution modeling we can more accurately simulate the high wind speeds and influence of polar lows on the ocean," Condron said. "The lower-resolution models currently used to make climate predictions very much miss the level of detail required to accurately simulate these storms."

By removing heat from the oceans, polar lows cause extremely dense cold water in the North Atlantic -- which acts as the catalyst of the thermohaline circulation, the large-scale ocean circulation responsible for transporting heat to Europe and North America, Condron and Renfrew discovered.

By simulating the effects of polar lows, Condron said that they discovered that the thermohaline circulation zone increases each year, resulting in an increase in the amount of heat transported to the UK and the rest of Europe.

"The fact that climate models are not simulating these storms is a real problem, because these models will wrongly predict how much heat is being moving northward towards the poles. This will make it very difficult to reliably predict how the climate of Europe and North America will change in the near future," he said.

The storms are "difficult to predict," Renfrew explained, but he said that their work shows that they "play an important role in driving large-scale ocean circulation" and that adding the polar lows to computer-generated climate models "results in significant changes in ocean circulation -- including an increase in heat travelling north in the Atlantic Ocean and more overturning in the Sub-polar seas."

"At present, climate models don't have a high enough resolution to account for these small-scale polar lows," the UAE professor added. "As Arctic Sea ice continues to retreat, polar lows are likely to migrate further north, which could have consequences for the 'thermohaline' or northward ocean circulation -- potentially leading to it weakening."