STORM TRACKER: The jet stream that carries moisture from Pacific storms over the U.S. has shifted north in recent decades, making the arid Southwest even drier.
Image: COURTESY OF STEPHANIE MCAFEE/UNIVERSITY OF ARIZONA/2008
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The already parched U.S. Southwest is drying up even more, at least in early spring, because of climate change. A new study in Geophysical Research Letters shows that since 1978, the jet stream that brings rainstorms from the Pacific over the western U.S. has been shifting northward—and so has the rain and snow.
"That northward shift in the storm track is tied to reduced early spring precipitation, especially over the southwest U.S.," says atmospheric scientist Stephanie McAfee of the University of Arizona (U.A.) in Tucson, who led the research identifying the loss of a few storms per season. "It looks like the northern Great Plains seem to get a little bit more rain."
The total amount is only a fraction of an inch, McAfee notes, drawing on precipitation and storm data from the U.S. National Oceanic and Atmospheric Adminstration. But this is lengthening "the dry season in parts of the country that are already quite arid," she says.
Greenhouse gases emitted by burning fossil fuels are piling up in the atmosphere, warming its lowest layer. At the same time, human-produced chemicals have eaten holes in the ozone layer over the poles, ultimately cooling the uppermost part of the atmosphere. This temperature differential creates pressure differences that have been shifting the powerful high-altitude winds known as jet streams in both the Northern and Southern hemispheres closer to the poles since the 1980s. "It's man-made either way you look at it," says U.A. biogeochemist Joellen Russell, senior author of the study.
Climate change has arrived in the Southwest in the form of an earlier seasonal shift to summerlike weather, bringing an end to April showers in the lowlands and spring snowfalls in the mountains. "The change so far in total precipitation is pretty small," Russell notes. But "we expect that this may continue or even get worse."
The Southwest is already suffering through an extended drought that has lowered water levels in Lake Mead and threatens agriculture. McAfee says the climatic shift may also decrease the mountain snowpack that provides water for cities as well as dry out soils, thereby starting fire season earlier in the year, although she has no data on those phenomena yet. "People are going to need to change a little bit in their expectations of what a season is going to be like," adds McAfee, who is now looking at how this is impacting area vegetation. "If we keep doing this, the climate response becomes more extreme."
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21 Comments
Add CommentWill there ever be a global warming story too moronic for SA to print? I think not. This one, though, is such a masterpiece of vapidity that a magazine with the word "scientific" in its name should print it as a shining example of anti-science, not science. Leave it to SA's editors, while carrying water for the looney left, to careen ever more radically down the road to unscientific oblivion.
Reply | Report Abuse | Link to thisBill McConnell
SciAm has become a left wing reactionary mouthpiece that has little or nothing to do with science anymore. My family has subscribed to SciAm for over 100 years and I have issues from the year the write brothers flew that were handed down to me. Sadly when my print subscription runs out I will not renew. The editors are just to liberal in what they deem suitable for this magazine. This story and the "Cement from CO2: A Concrete Cure for Global Warming?" story are prime examples.
Reply | Report Abuse | Link to thisBryan Albers
Hello Bill,
Reply | Report Abuse | Link to thisCould you please offer a specific critique of the article. Your entire post is fact free and full of empty insults. E.g, What exactly is anti-science in this article?
Well, Bill, this isn't as you seem to feel, a political issue. However, it does require a somewhat more open mind than you appear to possess. As the saying goes, "stupid is and stupid does." And Bryan, we'll (not) miss you.
Reply | Report Abuse | Link to thisIs any of this up to-date? It is the end of the drought here in Arizona. From a choice of light brown to dark gray brown to now park-like green everywhere due to early rain and good monsoons. Why not comment on how there are wildflowers now still blooming that i have not seen for years or more. Everyone loves to panic but they lose credibility when it is better than normal this year for Prescott Arizona area and beyond. How about CURRENT news rather than re-hashed sensationalism. Am I blind to the drought or is it really green here?
Reply | Report Abuse | Link to thisJulia in Skull Valley Arizona
Reply | Report Abuse | Link to thisgiday america we are facing exactly the same trend in southern Australia except the rain is being pushed further south
our area is facing its third year with zero irrigation allocation
water has increased from $10/megalitre (about a 50 metre swiming pool full) to currently $600
check this wwwmdbc gov.au click on link ;global warming causes rainfall decline
somehow i don't think the planet knows who is in the White House!
Reply | Report Abuse | Link to thisgiday America it's dry down under too
wwwmdbc.gov.au click on the link; Global warming causes rainfall decline
we are in our 10th year of drought here
never mind petrol (gas) is still cheap here , only $6.00 a gallon ($1.50/litre)
have anice day
Hey, kiwichick: As a pundit once said, there's no problem so bad that it can't get worse. Read Gaia by James Lovelock -- gives a great world view of what's happening.
Reply | Report Abuse | Link to thisHello Skyblue. I get the distinct impression that you did not read the article. May I also recommend you learn the distinction between weather and climate.
Reply | Report Abuse | Link to thisI was only commenting on the drought not climate change. Just like Katrina was not part of a new season of extra hurricanes, or flooding. It is not good to promote overly simplistic thinking or is it? Maybe humans need propaganda to get them going and not procrastinate like most do.
Reply | Report Abuse | Link to thisHi Skyblue, Unfortunately the drought is not over. You appear to be suffering from the same misconception that a lot of people in the Southwest have. Yes, it is very green right now and we also had an amazing spring wildflower season because of the early winter rains we recieved. That does not, however, compensate for the years of below normal rainfall that preceded this year. As a population we need to be concerned about long term trends in our climate, not year to year fluctuations. Unfortunately the drought is persisting and all of the best evidence suggests that it will continue and perhaps get worse as the climate changes. I really hope it doesn't but the evidence is pretty strong that it will. Dominic
Reply | Report Abuse | Link to thisHello Skyblue. In your original comment you asked the entirely rhetorical question of "is this article up to date?". You then cite as countering evidence, recent rains in your region. So in short you are comparing climate to anecdotal personal weather experience. If you think this article is propaganda please cite the evidence for that assertion, in regards to this article.
Reply | Report Abuse | Link to this"The Southwest is already suffering through an extended drought that has lowered water levels in Lake Mead and threatens agriculture. McAfee says the climatic shift may also decrease the mountain snowpack that provides water for cities as well as dry out soils, thereby starting fire season earlier in the year, although she has no data on those phenomena yet. "People are going to need to change a little bit in their expectations of what a season is going to be like," adds McAfee, who is now looking at how this is impacting area vegetation. 'If we keep doing this, the climate response becomes more extreme.'"
Reply | Report Abuse | Link to thisFor this year so far the rainfall totals have been normal or above normal for the state of Arizona see this drought index from NOAA: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif
RE: Propaganda here is the Wikipedia definition :"Propaganda is a concerted set of messages aimed at influencing the opinions or behaviors of large numbers of people. As opposed to impartially providing information, propaganda in its most basic sense presents information in order to influence its audience. Propaganda often presents facts selectively (thus lying by omission) to encourage a particular synthesis, or gives loaded messages in order to produce an emotional rather than rational response to the information presented. The desired result is a change of the cognitive narrative..." To link the previous drought to global warming is presenting " facts selectively (thus lying by omission) to encourage a particular synthesis..." I was asking about the omission of this year's data which can be evidenced by my observations here. The outlook from NOAA for the true southwest states is "improved" http://www.cpc.ncep.noaa.gov/products/expert_assessment/seasonal_drought.html
this statement in the title of this article is misleading "Things could get uglier for desert flowers looking to bloom in May--and for the region's water supply, year-round"
"The already parched U.S. Southwest is drying up even more, at least in early spring, because of climate change. A new study in Geophysical Research Letters shows that since 1978, the jet stream that brings rainstorms from the Pacific over the western U.S. has been shifting northwardand so has the rain and snow." The change in the jet stream is only one factor that influences rainfall . Anecdotally, this spring began early with monsoon-like rainfall. Fire danger days have been spaced far and few.
Hello SkyBlue. Once again you are confusing weather with climate. You also seem to not understand that this article is dealing with CLIMATE. The entire article talks of how the jet stream has been shifting north for the past 30 years. That means that "less rain and snow" for the southwest and more rain and snow for Great Plains. This article is concerned with long term climate trends, not season to season variability. That is why the peer reviewed paper that this article is reporting is talking about the TRENDS since 1978. Once again, please go learn the difference between weather and climate, they are not the same. While your looking that up please go look at what constitutes statistical significance in climatology.
Reply | Report Abuse | Link to thisSo what? Let it dry up. The US government and the far right are going to give away our country to the terrorists and thugs anyway and I don't want to be responsible for leaving anything clean to the terrorists/thugs. I say lets use up all the fossil fuels we can before they take over. It's just a matter of time. Besides science is just an opinion. It's just a best guess not a certainty.
Reply | Report Abuse | Link to thislike i said before i was only talking about the drought not the overall direction of the jet stream and the eventual CLIMAX of the climate. Peer reviewed does not mark the seal of truth only what some scientists agree with in specialized journals. i was and am not trying to be a climate change "naysayer" i have just seen too much over-dramatizations in the media and Scientific American is part of the media not a journal for meteorologists or climatologists nor is it even close to NOAA in detail. It seems that humans are so emotional about this subject that they are acting like the vaccine phobic parents grasping at straws to try to slight anyone who disagrees with them. The drought will only be declared "over" in hindsight, so Dominic seems the most calm here and will have to be the last person i agree with. To get personal if people are worried about drought and how the future climate will affect them, how about everyone check your water usage quantity and quality, me and my 3 dogs only use more or less 40 gallons of water per week my only weakness is my computer that takes electricity from the Hoover dam, i have no air conditioning etc. I know of no one who is willing to give up air conditioning or landscaping non-native plants or a water wasteful lifestyle. i think all data points are relevant and human usage is a large group of data points in the statistics of sustainability for humans living here and in climate directions [for it seems to be true that humans affect the climate eventually]. I was not dis-ing the whole article only the omission of this year's data point. This was a rant about media not people reporting data and trying to draw conclusions for better or worse.
Reply | Report Abuse | Link to thisHello Skyblue. Since this entire article discusses the findings of peer reviewed researched on the movement of the jet stream and what that means for the Southwest your anecdotes on how green is your valley are not relevant. If you have evidence that the jet stream has not been moving more north over the past thirty years, please present it. You airily dismiss peer review and yet you can not offer any serious critique.
Reply | Report Abuse | Link to thisi never once disputed the change in the jet stream ---you are fighting the wrong person here--my whole rant is about an unbalanced view intended to panic the public when the researcher her self says : "...thereby starting fire season earlier in the year, although she has no data on those phenomena yet. "People are going to need to change a little bit in their expectations of what a season is going to be like," adds McAfee, who is now looking at how this is impacting area vegetation. "If we keep doing this, the climate response becomes more extreme." She "...has no data yet ..." things are not absolute in science, theories are always being modified and
Reply | Report Abuse | Link to thisthe process of peer review is vital in confirming theories. "Two heads are better than one." but scientists are human and they are not immune from becoming "sheeple". Politics enter into every group in various severities.
And each profession has groups, associations professional "clubs".-I've seen it all from the inside quite ugly .
anyhoo you are fighting a straw man --not me
i presented more than anecdotes at this point you ignore the NOAA info and seem intent in arguing only for the sake of it
and are putting out not so subtle insults
so this is no longer productive for arriving at "truth"
Al Gore is the new pol pot of climate change instead of ground zero its scientific fact zero i have been in horticulture for 36 years and in those 36 years no two seasons have been the same My livelyhood depends on my understanding future weather patterns get your woolies on because the weather patterns are starting to go the other way , the planet is cooling again it must be global warming , all the hot air from bufoons that believe we are all doomed use your brains instead of borrowing others
Reply | Report Abuse | Link to this``dear trent ,the world did exist before 1978 .this world we live in is as far as i know began before 1956 going on anecdotal evidence from my parents the climate changes all the time remember the last ice age . those bloody eskimos burning their seal oil started all our problems m8 you must be right no more seal hunting for me
Reply | Report Abuse | Link to thisAfter reading the preceding posts, I believe that much of the confusion could've been cleared up had the article been longer. It's unfortunate that SciAm didn't give reporter, David Biello, enough space to flesh out the highlights of the research study. On another note, I find it offensive that certain bloggers make rude, almost ad hominem attacks when they don't like the content of an article. There are civil ways to contest the assertions of an author. You can ask pointed questions and request details where you find a lack of substance.
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