Brief but vicious Arctic storms known as polar lows are likely to become much less frequent as global warming intensifies, scientists in Britain determined on September 15. Polar lows brew in ice-free high latitudes in the North Atlantic in winter and can swiftly become a hazard for shipping and oil rigs.
The number of these storms averaged 36 per season in the 20th century, climatologists at the University of Reading said. By 2100, this tally would fall to between 17 and 23 per season, depending on concentrations of heat-trapping greenhouse gases in the air. "There would be roughly only half as many in future," Matthias Zahn, of the university's Environmental Systems Science Centre, told AFP. The simulation is based on three scenarios for greenhouse-gas emissions used by the UN's Intergovernmental Panel on Climate Change (IPCC).
The reason for the fall lies in a change in the difference in temperature between the ocean's surface and the mid-atmosphere.
This differential is what causes a polar low to develop. Changing the difference hampers the storm's formation and intensification, according to the paper, released by Nature, the British science journal. Zahn said further work was underway to simulate polar lows in the northern Pacific.
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