Drier, warmer springs in US Southwest stem from human-caused changes in winds

Aug 19, 2008
The late-winter/early-spring storm activity in the western US has shifted north since the late 1970s. This graphic shows how the peak winter storm tracks have shifted poleward since 1978. The blue line shows the storm track for February, March and April of 1978. The red line shows the track for the same months during the year 1997. Credit: Stephanie McAfee, the University of Arizona, 2008.

Human-driven changes in the westerly winds are bringing hotter and drier springs to the American Southwest, according to new research from The University of Arizona in Tucson.

Since the 1970s the winter storm track in the western U.S. has been shifting north, particularly in the late winter. As a result, fewer winter storms bring rain and snow to Southern California, Arizona, Nevada, Utah, western Colorado and western New Mexico.

"We used to have this season from October to April where we had a chance for a storm," said Stephanie A. McAfee. "Now it's from October to March."

The finding is the first to link the poleward movement of the westerly winds to the changes observed in the West's winter storm pattern. The change in the westerlies is driven by the atmospheric effects of global warming and the ozone hole combined.

"When you pull the storm track north, it takes the storms with it," said McAfee, a doctoral candidate in the UA's department of geosciences.

"During the period it's raining less, it also tends to be warmer than it used to be," McAfee said. "We're starting to see the impacts of climate change in the late winter and early spring, particularly in the Southwest. It's a season-specific kind of drought."

Having drier, warmer conditions occur earlier in the year will affect snowpack, hydrological processes and water resources, McAfee said.

Other researchers, including the UA's Laboratory of Tree-Ring Research Director Tom Swetnam, have linked warmer, drier springs to more and larger forest fires.

McAfee's co-author Joellen L. Russell said, "We're used to thinking about climate change as happening sometime in the future to someone else, but this is right here and affects us now. The future is here."

McAfee and Russell, a UA assistant professor of geosciences, will publish their paper, Northern Annular Mode Impact on Spring Climate in the Western United States, in Geophysical Research Letters, a journal of the American Geophysical Union. The National Oceanic and Atmospheric Administration funded the research via the Climate Assessment for the Southwest program at the UA.

Atmospheric scientists have documented that the westerly winds, or storm track, have been shifting poleward for several decades. The southwestern U.S. has experienced less winter precipitation during the same period.

Computer models of future climate and atmospheric conditions suggest the storm track will continue to move north and that precipitation will continue to decrease in the southwestern U.S.

The timing of the change from wet, cool winter weather to the warmer dry season is important for many ecological processes in the arid Southwest. Therefore, McAfee wanted to know how the shift in the storm track affected precipitation during the transition from winter to spring.

For the period 1978 to 1998, the researchers compared the month-to-month position of the winter storm track, temperature and precipitation records from the western U.S., and pressure at different levels in the atmosphere.

The team used a statistical method called Monte Carlo simulations to test whether the coincidence of storm track and weather patterns had occurred by chance.

Russell said the results of the simulation showed, "It's very rare that you get this distribution by chance." Therefore, she said, the changes in late winter precipitation in the West from 1978 to 1998 are related to the changes in the storm track path for that same time period.

McAfee said her next step is investigating whether western vegetation has changed as the storm track has changed.

Source: University of Arizona

Explore further: Bridgmanite: World's most abundant mineral finally named

add to favorites email to friend print save as pdf

Related Stories

NASA ocean data shows 'climate dance' of plankton

Sep 30, 2014

The greens and blues of the ocean color from NASA satellite data have provided new insights into how climate and ecosystem processes affect the growth cycles of phytoplankton—microscopic aquatic plants ...

Satellite video captures the eastern US winter storm track

Mar 04, 2014

As NOAA's GOES-East satellite sat in a fixed orbit in space it monitored and provided visible and infrared imagery of the major winter storm that hit the U.S. east coast on March 2 and 3. Now, that data has been compiled ...

Cassini tracks clouds developing over a Titan sea

Aug 12, 2014

(Phys.org) —NASA's Cassini spacecraft recently captured images of clouds moving across the northern hydrocarbon seas of Saturn's moon Titan. This renewed weather activity, considered overdue by researchers, ...

Recommended for you

Bridgmanite: World's most abundant mineral finally named

10 hours ago

A team of geologists in the U.S. has finally found an analyzable sample of the most abundant mineral in the world allowing them to give it a name: bridgmanite. In their paper published in the journal Science, the te ...

Volcano in south Japan erupts, disrupting flights

17 hours ago

A volcano in southern Japan is blasting out chunks of magma in the first such eruption in 22 years, causing flight cancellations and prompting warnings to stay away from its crater.

User comments : 17

Adjust slider to filter visible comments by rank

Display comments: newest first

Zig158
3.7 / 5 (13) Aug 19, 2008
I wonder if McAfee and Russell failed American history? At one-point crops used to grow past the 100th meridian in the Dakotas. As you should know today they do not grow past the 100th meridian without irrigation, why is that? Could it be that the jet stream at one point fallowed a different path making rain that now falls on the southwest, fall on the upper Midwest? Could the variation in jet stream be a natural phenomenon?
That is not possible because a computer model says so, and computer models know all! ALL I SAID!
Velanarris
3.6 / 5 (12) Aug 19, 2008
Because winds never ever shift direction on their own.


Man they're throwing grant money at anyone who wants to push the human based global warming agenda.
jscroft
3.8 / 5 (13) Aug 19, 2008
"Human-driven changes in the westerly winds are bringing hotter and drier springs...." Well, they established that the springs are hotter and drier, but they didn't connect the dots to any human cause! All they established was that the changes were "not random," as if the only possible alternative were anthropogenic climate change. What a blatant straw man!
MikeB
3.8 / 5 (10) Aug 19, 2008
When will science reestablish itself into climatology?
agg
3.8 / 5 (10) Aug 19, 2008
I blame man-bear-pig for this.

Why are all the computer "models" for weather systems both calibrated and interpreted by CHICKEN LITTLE ???

STOP GIVING THESE CLIMATE PSYCHICS MONEY.
deatopmg
3.8 / 5 (10) Aug 19, 2008
"human driven climate..." are code words for; "send more grant money"

And agg it's; "psychotics" not "psychics"
agg
3.8 / 5 (10) Aug 19, 2008
McAfee's co-author Joellen L. Russell said, "We're used to thinking about climate change as happening sometime in the future to someone else, but this is right here and affects us now. The future is here."

He's right, we need to be as biased as possible so that all our so called "science" can be predetermined, that way we can sit back and watch the grant money roll in.
Modernmystic
3.7 / 5 (9) Aug 19, 2008
Man with "science" like this being thrown about it won't be long before even the most deluded gorists will have to admit something fishy is going on in climate science circles.

Let them rave on....
THEY
3.9 / 5 (10) Aug 19, 2008
Maybe I am a nutcase... but.. it doesn't appear the article explains HOW humans have changed the winds..... Will the next article blame it on all the solar and wind power generated in California??? Who writes this BS?

As you all said, jet streams DO and ALWAYS WILL change. I am sick of this media hype!
GrayMouser
4.2 / 5 (5) Aug 19, 2008
Two questions:
1) Exactly HOW rare is this weather pattern?
2) How much energy is required to shift the westerly winds from where they were to where they are?

I suspect the answers to those questions are "Ummmmm...." and "More energy than humans produce in a year".
InformedSkeptic
2.3 / 5 (11) Aug 19, 2008
Oh sure - where did all of you get your science education? How many of you read the actual paper as opposed to the article? If you are at all familiar with the science of climate change, then you'll realize that the paper describes one effect of additional energy in the climate system. This energy is not fiction, but well documented by the IPCC scientists and others around the world as being contributed by human activity. Humans are changing the climate. Whether you believe that to be true or not is irrelevant.
Modernmystic
3.5 / 5 (8) Aug 19, 2008
Atta boy Skeptic you tell 'em!

*snicker*
bobwinners
2.5 / 5 (8) Aug 19, 2008
I agree, Skeptic. "Stuff used to grow N of 100th meridian in whereever." No statistics or reference was provided to back this up. Might as well say that it used to rain a lot more in the central Sahara.
But then, it is useless to arue with closed minds.
Modernmystic
3.5 / 5 (8) Aug 20, 2008
It actually did used to rain a lot more in the Sahara, it's just that there weren't any coal burning power plants back then to blame the shift on.
jburchel
3.5 / 5 (8) Aug 20, 2008
"Humans are changing the climate. Whether you believe that to be true or not is irrelevant."

WTF? Maybe irrelevant if you are God (as these dorks seem to think they are), but on EARTH where PEOPLE live, what PEOPLE believe is absolutely RELEVANT. If I bought what these wackos are selling, then I would vote for the most massive tax increase in history (aka "cap and trade"), but since I don't believe them, I will fight against the tax grab in order to keep my own money. Sounds pretty relevant to me... To the tune of trillions of dollars of our money.
GrayMouser
4 / 5 (4) Aug 21, 2008
Oh sure - where did all of you get your science education? How many of you read the actual paper as opposed to the article? If you are at all familiar with the science of climate change, then you'll realize that the paper describes one effect of additional energy in the climate system. This energy is not fiction, but well documented by the IPCC scientists and others around the world as being contributed by human activity. Humans are changing the climate. Whether you believe that to be true or not is irrelevant.


The IPCC "Scientists" didn't prove anything. They did a (IMHO) limited review of published (and unpublished) papers. There are a large number of well documented problems with the IPCC:
1) Reviewing unpublished papers was a violation of their own rules.
2) Ignoring the responses (what few there were) of their reviewers was a violation of scientific ethics.
3) Writing their executive summaries prior to the production of the various chapters was out and out fraud since there was no way the authors were going to let those chapters contradict the summaries.
4) Averaging the output of multiple computer models, that don't produce identical results, and passing that off as proof of anything is a joke.
5) Allowing people with conflicts of interest to remain unidentified among the authors (as long as it was in a specific direction) is disingenuous.
6) Pretending that all of the reviewers looked at all of the report (instead of the low percentage that did) and that they all agreed is fraudulent.

The simple fact is the IPCC isn't a scientific body and never has been. IMHO, it's purely political and is being used to drive political changes.
Velanarris
3.9 / 5 (7) Aug 21, 2008
Oh sure - where did all of you get your science education? How many of you read the actual paper as opposed to the article? If you are at all familiar with the science of climate change, then you'll realize that the paper describes one effect of additional energy in the climate system. This energy is not fiction, but well documented by the IPCC scientists and others around the world as being contributed by human activity. Humans are changing the climate. Whether you believe that to be true or not is irrelevant.


You do realize that multiple astrophysicists have written papers about climate change stemming from the dramatic increase in solar energy over the past 70 years, but none of their papers are ever considered by climatologists based on the "LOL ASTROPHYSICS" attitude that climatologists have taken in regard to changes in ambient energy in the environment.

The climatic cycle and global warming perceived by climatologists match the exact increase in what physicists are seeing from solar energy output scales.

Summary: When the sun gets hotter, the Earth gets hotter. Proven by 3 things

1) Mean temperature increases recorded on Earth have increased at the same rate as recorded mean temperature increases on other planets in the solar system.

2) Human greenhouse gas (big misnomer) contribution totals less than 1/3 of a percent and never include calculations for water vapor (the real temperature change induction mechanism of the planet).

3) Solar energy output matches perceived climate change and has as been modeled back to pre-cambrian times.

It's pretty simple, when you remove the politics and theories and look at the hard data, articles like the above are intellectual mistreatment.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.