Extreme weather changes in front of us

Extreme weather changes in front of us

Summary: Researchers from Purdue University have used their supercomputers to run the largest simulation of what could become the weather in the U.S. between 2071 and 2095. And their model, which was validated by using data from last century, predicts more extreme temperatures throughout the country.

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Researchers from Purdue University have used their supercomputers to run the largest simulation of what could become the weather in the U.S. between 2071 and 2095. And their model, which was validated by using data from last century, predicts "more extreme temperatures throughout the country and more extreme precipitation along the Gulf Coast, in the Pacific Northwest and east of the Mississippi." The computer model used a grid with an 25-km horizontal resolution and required five months of computing time. Still, the researchers think they need a computer at least 100 times as powerful as the clusters they used to really improve the accuracy of their predictions.

Here are two short excerpts of the Purdue University news release.

The climate model, run on supercomputers at Purdue University, takes into account a large number of factors that have been incompletely incorporated in past studies, such as the effects of snow reflecting solar energy back into space and of high mountain ranges blocking weather fronts from traveling across them, said Noah S. Diffenbaugh, the team's lead scientist and a member of the Purdue Climate Change Research Center.
Diffenbaugh said a better understanding of these factors -- coupled with a more powerful computer system on which to run the analysis -- allowed the team to generate a far more coherent image of what weather we can expect to encounter in the continental United States for the next century. Those expectations, he said, paint a very different climate picture for most parts of the country.

The research work has been published by the Proceedings of the National Academy of Sciences under the title "Fine-scale processes regulate the response of extreme events to global climate change" (published online before print, October 19, 2005).

Here are two links to the abstract and to the full paper (PDF format, 5 pages, 740 KB), from where the details and quotes below have been extracted.

Here are the characteristics of the model used for this computer simulation.

The grid was centered at 39.00°N and 100.00°W and consisted of 145 points in the latitude direction and 220 points in the longitude direction. Grid points were separated at 25-km horizontal resolution with 18 levels in the vertical. We have performed two model integrations.

The researchers performed two reference integrations (RF) on the model, first for the period 1961 through 1985 to validate the model, then for the period covering the years 2071 to 2095.

Below is an image showing one of the results obtained for this second period. It shows the anomalies in mean heat-wave length. This T95 index value on this map was "calculated as the mean of the 95th percentile daily temperature maxima at each grid point in each of the 25 years of the RF integration" (Credit: Noah Diffenbaugh).

Additional heat-wave days in 2095

As you can see, anomalies were mostly positive, indicating higher temperatures than today.

Peak values of up to 15 days per event (up to 550%) stretched from northern Mexico into the northern Great Basin, with substantial spatial variability linked to the rugged terrain of the Great Basin. The northeast Atlantic coast showed little response in mean heat-wave length, whereas eastern Texas showed a strong response.

Here is a short summary of the results obtained from this simulation.

Our results indicate that, should atmospheric greenhouse gas concentrations continue to increase over the next century, changes in the frequency and magnitude of extreme events are likely to be dictated not only by changes in large-scale climate dynamics but also by a suite of climate-system modifiers operating at very fine scales.
We project substantial, spatially heterogeneous increases in both hot and wet events over the contiguous United States by the end of the next century, suggesting that consideration of fine-scale processes is critical for accurate assessment of local- and regional-scale vulnerability to climate change.

And it seems that all human activities will be affected.

The changes in frequency and magnitude of extreme temperature and precipitation events projected here could have dramatic impacts on human and natural systems. For instance, agricultural production, water storage, seasonal energy demands, catastrophic flood loss, and human mortality could all be substantially affected. Further, natural ecosystems could be severely impacted through changes in plant community composition and biogeography and increases in risks of extinction, invasion, and exotic disease.

After these alarming predictions, let's return to the Purdue news release which points out to some reasons for hope.

The model, Diffenbaugh said, assumes that greenhouse gases will attain a concentration more than twice their current levels, but he said he is confident that the model's performance gives as accurate a picture of the future as we can hope for at the moment.
Diffenbaugh emphasized that, while the model was in no way designed to return an alarmist image of our climate's future, the picture it painted should be considered.

Now, we can just hope that enough countries and industries will limit their greenhouse gases emissions and that the concentration of CO2 in the atmosphere will not be multiplied by two before the end of the century.

Sources: Purdue University news release, October 17, 2005; and various web sites

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9 comments
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  • Positive?

    What the hell?

    "As you can see, anomalies were mostly positive, indicating higher temperatures than today"

    Yes that's good news, considering it was so hot in MICHIGAN that my Air Conditioner somehow broke during the record high over this summer, our Winters have gradually become nothing over my young life, and the heat has continued to rise, when the hell did that become a good thing? I'm not up for 365 days of Summer.

    This isn't one of those Republican "Hey Global Warming isn't so bad!" Type of things is it? I sure hope it's just an appreciation of heat and not the former.
    Revrant
    • We see the opposite

      This last summer has been cool and extremely wet. I live in a desert! I'm talking cactus and sand. Last summer we got maybe 2 weeks of warm weather (low 80s). That's it. We I was kid it used to 100+ from June to Mid September. You'd be lucky to see a 5 a minute rain shower every 5 or weeks or so. It was dry and dusty. Now it green from March to November. Talk about a change!
      voska
    • Not Exactly "Positive"

      I believe that the authors of the study meant that the values of the changes in temperature (delta sub-t) were "positive" in a mathematical sense. An increase in the value.

      However, I'm with you. Not really into 365 days of summer. If I were, I'd live in Death Valley. Positive (increasing) temperature changes are not really a positive (good) thing. Warmer water temperatures in the south Atlantic and the Gulf of Mexico are believed to have contributed this year to the cataclysmic strength of Hurricane Katrina, and the record number of hurricanes and tropical storms.

      The politicization of science seems, sadly, unavoidable. My personal advice - keep watching, keep reading, consider the sources, the agendas, and follow the money. One will eventually be able to see through the BS to the truth. Remember - when it comes to capitalism & government, just about any amount of cynicism is justified.
      d10ckMan
  • Climate change

    That's great - but I can't trust them to predict tommorrow's weather correctly - why should I believe them about longer periods of time?

    "The model, Diffenbaugh said, assumes . . ."

    Big, red warning flag: Remember that assume is ass-u-me. The biggest mistake people often make is using inaccurate or unrealistice assumptions.
    CobraA1
  • Weather Simulations take time.

    It's like the old joke:
    They now have a computer system which will calculate tomorrow's weather with perfect accuracy. The program, however, requires 48 hours to run.
    docsavage
  • extreme nonsense on the front burner

    This global warming thing is getting ridiculous. Humans have been keeping tabs on the weather using scientfic instruments for let's say 100 to 200 years (a generous estimate). Yet the earth had been experiencing weather unrelated to man for BILLIONS of years! Even if accurate weather data existed for all of recorded history (5000 years) it would be but an insignificant blip in the ongoing scenario.

    Yet here we are today running computer programs and "predicting" all kinds of results that, in fact, we have absolutely NO control over. This is a first-class ego rush for somebody, a political minefield, and the modern equivalent of the rain-dance and the witch-hunt all wrapped up in scientific-sounding glitz.

    If someone could simply explain the well-documented coming and going of the ICE AGES that are preserved in the geological record, I would then be inclined to listen to their opinion about other factors that might influence the earth's weather.

    Again, this global warming thing is akin to the "repressed memory" fad of a few years ago wherby children (and even adults) were "interviewed" by experts who claimed they could find proof of past abuse. Innocent parents and teachers were then dispatched to jail. The evil of pseudoscience cannot be overestimated. In today's world there is a large population of scientific illiterates that love easy answers. They absorb crap from the mass media and then permit all matter of hell to break loose, thinking they "know" about something they don't even comprehend.

    Computer geeks, SHUT UP about the weather unless you have real proof and repeatable results based on the application of rigorous science.
    dmennie
    • OK....

      You're not that bright, are you? In fact they do have data and models for earler periods. They take ice cores from those parts of the world that have been frozen for thousands of years and analyze the atmosphere trapped in it. They analyze the "records" kept over centuries by trees. They look everywhere and anywhere to find data to help analyze climactic changes and cycles. CO2 is a greenhouse gas. No rational person should be capable of denying that. We pour billions of tons of it into the atmosphere at the same time we are damaging the planet's systems that might help balance it out. We affect the albedo of the planet with our construction. They do explain things. You just aren't bright enough to find the answers. Check out realclimate.org. They are NOT "computer geeks". They are climatologists. Of course I think you've made up your mind and wouldn't listen to them anyway.
      JimSatterfieldW
      • not OK....

        Here we find a nice, scientific argument "you're not too bright" lobbed forth twice in one paragraph -- probably because the author (JimSatterfieldW) can't muster up any hard facts to support his opinions. ("Rational people" can believe whatever they want, but this does not make it so.)

        Sure, I am aware of trapped gas found in ice cores and the climate "history" represented by tree-ring growth. The problem with all this evidence is in the atribution. Nobody has global weather records, temperature readings, eyewitness accounts, or anything else to go along with the core samples from eons ago. This means composing a THEORY to explain why one tree ring is thicker than the others; why one gas bubble from an ice core has more nitorgen, more oxygen or less carbon dioxide than expected.

        My gripe is that these most pliable THEORIES are being used to justify POLITICAL POSITIONS and thereby ENACT LAWS that affect everybody right now, even though the intellectual underpinning is FLIMSY to NON-EXISTENT. The earth-warming advocates (be they computer geeks, climatologists, or pandering politicians) are empowering themselves to "solve" a problem they do not understand and ultimately cannot grasp given the evidence at hand thus far.

        Again, my example of past ICE AGES should sound a warning. If no one can explain why the Earth warms/cools in cycles that allow mile-thick glacers to form in New England on a regular basis, why should anyone take man-made emissions so seriously GIVEN THE GREATER SCHEME OF THINGS that are already well-established scientific facts based on the geological record (not just theories).

        Would not the eruption of one or two large VOLCANOS change the global atmosphere more in a week than mankind has managed to do over the past 500 years? I believe you really need to look at global weather with these kind of perspectives in mind rather than sniffing the tailpipe of every SUV that rolls down the highway.

        PS: I hate SUVs, would not drive one, do not work for the oil industry or General Motors. I DO respect genuine science and HATE those who twist a few selected, scary "facts" together (typically out-of-context) to secure some career goal or short-term political advantage. We all loose when these types get the upper hand.
        dmennie
  • Earth Wobbles as poles shift

    For a good number of years I have kept track and seen the forecasts of Her Holiness Hehpsehboah A. In which she has the longer and most accurate track record that exists. These extreme weather patterns are the signs of the earth wobbling due to the magnetic poles shifting, at the same time, during this shifting the actions mankind is doing has great effect on how little or harsh these conditions are. Example, war. blowing bombs. the vibration rattles and oil. sucking it from the earth is like sucking the blood out of any living thing. thus creating an imbalance.
    usersmiley