Washington: Contrary to popular belief, cold snaps like the ones that hit the eastern United States in the past winter are not a consequence of climate change, says a new study.
The results, published in the Journal of Climate, showed that global warming actually tends to reduce temperature variability.
Repeated cold snaps led to temperatures far below freezing across the eastern United States in the past two winters. Parts of the Niagara Falls froze, and ice floes formed on Lake Michigan.
But scientists at ETH Zurich in Switzerland and the California Institute of Technology in the US led by Tapio Schneider, professor of climate dynamics at ETH Zurich, found that the extreme winters were not a result of climate change.
They used climate simulations and theoretical arguments to show that in most places, the range of temperature fluctuations will decrease as the climate warms.
So not only will cold snaps become rarer simply because the climate is warming. Additionally, their frequency will be reduced because fluctuations about the warming mean temperature also become smaller.
However, Schneider noted that "despite lower temperature variance, there will be more extreme warm periods in the future because the Earth is warming".
Using a highly simplified climate model, they examined various climate scenarios to verify their theory.
It showed that the temperature variability in mid-latitudes indeed decreases as the temperature difference between the poles and the equator diminishes.
Climate model simulations by the Intergovernmental Panel on Climate Change (IPCC) showed similar results: as the climate warms, temperature differences in mid-latitudes decrease, and so does temperature variability, especially in winter.
Temperature extremes will therefore become rarer as this variability is reduced. But this does not mean there will be no temperature extremes in the future, the researchers added.