Study: Global warming not to blame for fierce winter

Findings from Swiss-American team present nuanced view of how climate change affects weather extremes

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One of this past winter’s northeastern snowstorms swirls off the coast of New England in the satellite image via NASA Earth Observatory.

Staff Report

FRISCO — Adding more fuel to the debate over climate change and extreme weather, Swiss and American scientists this week said their new study shows that global warming tends to reduce temperature variability.

The cold and snowy weather that gripped much of the eastern U.S. this winter was probably not linked to Arctic amplification and increased waviness of the jet stream, according to the scientists with ETH Zurich and the California Institute of Technology.

Changes in the north-south difference in temperatures play a greater role in modifying temperature variability than changes in the jet stream, the researchers said.

Tackling the question from a different angle, the scientists used climate simulations and theoretical arguments to show that in most places, the range of temperature fluctuations will decrease as the climate warms. They concluded there will be fewer cold snaps because fluctuations from the warming mean temperature will be smaller, the scientists wrote in the latest issue of the Journal of Climate.

The researchers started with the baseline concept that higher latitudes are  warming faster, which means that the temperature difference between the equator and the poles is decreasing. As that contrast shrinks, air masses would start having more similar temperatures, regardless of whether they flow from the south or north.

Using a highly simplified climate model, they examined various climate scenarios to verify their theory. It showed that the temperature variability in mid-latitudes 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.

None of this means there will be no temperature extremes in the future.

“Despite lower temperature variance, there will be more extreme warm periods in the future because the Earth is warming,” said study leader Tapio Schneider.

The researchers limited their work to temperature trends. Other extreme events, such as storms with heavy rain or snowfall, can still become more common as the climate warms, as other studies have shown.

Schneider wants to explore the implications these results have in further studies. In particular, he wants to pursue the question of whether heatwaves in Europe may become more common because the frequency of blocking highs may increase. And he wants to find why these high pressure systems become stationary and how they change with the climate.

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2 thoughts on “Study: Global warming not to blame for fierce winter

  1. “…global warming tends to reduce temperature variability.”
    What a ridiculous statement! The left is getting desperate to try and re-define the global warming premise and make any normal weather look like it was caused by GW …

  2. This work refers mainly to air temperatures. I suspect the recent winter patterns are due to ocean temperature variations. The effect may be temporary but the warmer water off California seems to be responsible for or related to the jet stream extreme patterns– which are changing to a more southwest to northeast pattern at the west coast, from the previous west to east. The report of the perturbation of the tropical water flow (the gulf stream) from south to north on the east coast, caused by cold water flow increases from Greenland ice melt, will affect weather and climate in Europe (perhaps in northeastern US and Canada) in the same way. Much of northern Europe, including Ireland, Scotland, and Scandinavia are made habitable by the warm gulf stream water. If it’s being diluted or driven in another direction, it will change climate in those places.May be temporary, but temporary in earth terms is tens or hundreds of years.

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