New study shows arctic warming contributes to drought

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When the Arctic warmed after the ice age 10,000 years ago, it created perfect conditions for drought.

According to new research led by a University of Wyoming scientist, similar changes could be in store today because a warming Arctic weakens the between the tropics and the poles. This, in turn, results in less precipitation, weaker cyclones and weaker mid-latitude westerly wind flow—a recipe for prolonged drought.

The difference between the tropics and the poles drives a lot of weather. When those opposite temperatures are wider, the result is more precipitation, stronger cyclones and more robust wind flow. However, due to the Arctic ice melting and warming up the poles, those disparate temperatures are becoming closer.

"Our analysis shows that, when the Arctic is warmer, the jet stream and other wind patterns tend to be weaker," says Bryan Shuman, a UW professor in the Department of Geology and Geophysics. "The temperature difference in the Arctic and the tropics is less steep. The change brings less precipitation to the mid-latitudes."

Shuman is a co-author of a new study that is highlighted in a paper, titled "Mid-Latitude Net Precipitation Decreased With Arctic Warming During the Holocene," published today (March 27) online in Nature, an international weekly science journal. The print version of the article will be published April 4.

Researchers from Northern Arizona University; Universite Catholique de Louvain in Louvain-In-Neuve, Belgium; the Florence Bascom Geoscience Center in Reston, Va.; and Cornell University also contributed to the paper.

"The Nature paper takes a global approach and relates the history of severe dry periods of temperature changes. Importantly, when temperatures have changed in similar ways to today (warming of the Arctic), the mid-latitudes—particularly places like Wyoming and other parts of central North America—dried out," Shuman explains. "Climate models anticipate similar changes in the future."

Currently, the northern high latitudes are warming at rates that are double the global average. This will decrease the equator-to-pole temperature gradient to values comparable with the early to middle Holocene Period, according to the paper.

Shuman says his research contribution, using geological evidence, was helping to estimate how dry conditions have been in the past 10,000 years. His research included three water bodies in Wyoming: Lake of the Woods, located above Dubois; Little Windy Hill Pond in the Snowy Range; and Rainbow Lake in the Beartooth Mountains.

"Lakes are these natural recorders of wet and dry conditions," Shuman says. "When lakes rise or lower, it leaves geological evidence behind."

The researchers' Holocene temperature analysis included 236 records from 219 sites. During the past 10,000 years, many of the lakes studied were lower earlier in history than today, Shuman says.

"Wyoming had several thousand years where a number of lakes dried up, and sand dunes were active where they now have vegetation," Shuman says. "Expanding to the East Coast, it is a wet landscape today. But 10,000 years ago, the East Coast was nearly as dry as the Great Plains."

The research group looked at the evolution of the tropic-to-pole temperature difference from three time periods: 100 years ago, 2,000 years ago and 10,000 years ago. For the last 100 years, many atmospheric records facilitated the analysis but, for the past 2,000 years or 10,000 years, there were fewer records available. Tree rings can help to expand studies to measure temperatures over the past 2,000 years, but deposits, cave deposits and glacier ice were studied to record prior temperatures and precipitation.

"This information creates a test for ," Shuman says. "If you want to use a computer to make a forecast of the future, then it's useful to test that computer's ability to make a forecast for some other time period. The geological evidence provides an excellent test."


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More information: Cody C. Routson et al, Mid-latitude net precipitation decreased with Arctic warming during the Holocene, Nature (2019). DOI: 10.1038/s41586-019-1060-3
Journal information: Nature

Citation: New study shows arctic warming contributes to drought (2019, March 27) retrieved 23 May 2019 from https://phys.org/news/2019-03-arctic-contributes-drought.html
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Mar 28, 2019
When those opposite temperatures are wider, the result is more precipitation, stronger cyclones and more robust wind flow. However, due to the Arctic ice melting and warming up the poles, those disparate temperatures are becoming closer.

Wait a sec. We've been told, ad nauseum, that global warming is increasing the frequency and strength of storms. Now it's the opposite. You people have got to get your story straight. You're starting to look like schizophrenics.

Mar 28, 2019
When those opposite temperatures are wider, the result is more precipitation, stronger cyclones and more robust wind flow. However, due to the Arctic ice melting and warming up the poles, those disparate temperatures are becoming closer.

Wait a sec. We've been told, ad nauseum, that global warming is increasing the frequency and strength of storms. Now it's the opposite. You people have got to get your story straight. You're starting to look like schizophrenics.


If you didn't have any cherry picked data to refute, you wouldn't have any data at all. It never ceases to amaze me that people who know absolutely nothing about science will come onto a science forum and make complete fools of themselves.

Mar 28, 2019
DOH ! askdaddy antigoracle sockpuppet slaps himself silly as parsec knocks him out of the field .. yet again...a LOL !

Mar 28, 2019
Idiots, more total BS from alarmists. So cooling will make it rain? Dopes.

Mar 28, 2019
Wait a sec. We've been told, ad nauseum, that global warming is increasing the frequency and strength of storms. Now it's the opposite
There are more storms but they are drier. AGW causes bluster.

So the poles are melting, putting more moisture into the atmosphere, which causes more drought. Boy this climatology stuff is far too complicated for the normal individual.

Mar 28, 2019
No drought in California.
https://www.droug...lifornia

Mar 28, 2019
Idiots, more total BS from alarmists. So cooling will make it rain? Dopes.


Warm air = less mixing with air sufficiently cold to produce rain. But when it does occur the mixing is amplified by the convection to produce more condensation and ultimately more rain fall for many storms.

Overall Warming = Drying, which is why the central U.S. is reverting back to desert conditions.


Mar 28, 2019
"No drought in California."

For the first time in 18 years.

Won't last long given current trends.

Mar 28, 2019
Liar.. Liar... Pants on fire...

"We've been told, ad nauseum, that global warming is increasing the frequency and strength of storms."

Mar 31, 2019
It is impossible to make these predictions. A change in one variable out of a 100 variables can change the outcome of these predictions. All we can say, all we can ever say, is that the only thing that is constant, is we can make this worse.

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