Study finds massive climate change in North America before there was even an argument about it

From Vanderbilt University and the “climate has never been static” department:

Reconstructing topsy-turvy paleoclimate of western US 21,000 years ago

Improves climate models developed to predict future rainfall patterns

Reconstruction of the climate 21,000 years ago at the peak of the last ice age in the western US found that the transition between the dryer zone in the north and wetter zone in the south ran diagonally from the northwest to southeast. Credit :Jessica Oster, Vanderbilt University

Reconstruction of the climate 21,000 years ago at the peak of the last ice age in the western US found that the transition between the dryer zone in the north and wetter zone in the south ran diagonally from the northwest to southeast. Credit :Jessica Oster, Vanderbilt University

Climate scientists now put the odds that the American Southwest is headed into a 30-year “mega drought” at 50/50. Meanwhile, the forecast for the Pacific Northwest is continued warming with slightly drier summers and even wetter winters.

However, 21,000 years ago, at the peak of the last Ice Age, a period known as the Last Glacial Maximum, the Southwest was wetter than it is today – much wetter – and the Northwest was drier – much drier.

A team of scientists from Vanderbilt and Stanford universities have created the first comprehensive map of the topsy-turvy climate of the period and are using it to test and improve the global climate models that have been developed to predict how precipitation patterns will change in the future. Their efforts are described in a paper published online on Feb. 23 by the journal Nature Geoscience.

“Most of the previous research of the past climate in this region is based on detailed studies of specific sites,” said the lead author Jessica Oster, assistant professor of earth and environmental sciences at Vanderbilt University. “We combined these records to create a detailed map of past climate change in the American West. We then compared this map to computer climate models to understand what caused these changes.”

“Our previous research used field studies to understand the history of climate change in the Western US,” said study coauthor Kate Maher, assistant professor of geological and environmental sciences at Stanford University. ” It was amazing to see how our results, when combined with work of many other research groups and compared to the newest generation of climate models, revealed a consistent story about how rainfall patterns were altered in the past.”

One of the reasons that Oster and her colleagues picked this region to map is because the mid-latitudes, in general, and the western United States, in particular, are regions where the climate models tend to disagree on the magnitude and, in some cases, even the direction that precipitation patterns will change in the future.

“This is a transition zone. There are strong competing effects such as changes in the large-scale atmospheric circulation, sea surface temperature changes like El Niño and La Niña and the dynamics of westerly storm tracks that all interact at the mid-latitudes,” said Stanford co-author Matthew Winnick who contributed to the study with fellow doctoral student Daniel Ibarra. “As a result, understanding the exact nature of how these different effects express themselves to form the north/south transition zone will be extremely important for freshwater resource management in major population centers across the Western US.”

Of course, there aren’t any direct records of precipitation levels thousands of years ago. So climate scientists rely on indirect means, called proxies, to reconstruct past variations in precipitation patterns. In this case, the researchers combined records of ancient lake levels, location and extent of glaciation, variations in the composition of stalagmites in caves, and evidence for changes in vegetation and subsurface soil deposits associated with water table depth. (One of the smelliest proxies that they used is pollen preserved in ancient packrat middens.)

During the Last Glacial Maximum, Canada was completely inundated by the massive Laurentide Ice Sheet. A number of the site-specific studies in the Northwest had provided evidence for a drier climate during the period, while similar studies in the Southwest found evidence for a wetter climate. For instance, a 1997 vegetation study from the University of Wisconsin found that much of the Northwest was covered by polar desert or tundra while the Southwest was covered by extensive conifer and broadleaf forest. However, there was also conflicting evidence of drier conditions at some sites in Utah and Colorado and of wetter conditions in Idaho and Montana.

“People hypothesized that the transition between the two climate zones ran along a straight east-west line, but that didn’t work very well,” said Oster. “Our study indicates that the transition zone is angled from the northwest to the southeast.” This explains the drier conditions in Utah and Colorado. Their analysis also found that the wetter sites in the north were situated next to large inland lakes that existed at the time, so they attribute them to local, lake effects.

Two basic theories have been advanced to explain the dramatically different rainfall patterns of this period:

  • One is that the cold air above the Laurentide Ice Sheet created a tremendous high pressure system that shifted the polar jet stream to the south, pushing the track followed by winter storms down into the Southwest, which had the effect of dramatically reducing the amount of rainfall in the Northwest while increasing it in the Southwest.
  • An alternative explanation is that the subtropical jet stream was enhanced, increasing the frequency with which the Southwest was hit by “Pineapple Expresses:” water-saturated subtropical plumes of air that periodically swing up from Hawaii and hit the West Coast and these days cause serious flooding. When combined with a strengthened summer monsoon, this could also explain the wetter conditions in the Southwest.

When the researchers compared their results with the output of a number of climate models, they found that several of the newer models that have higher resolution and use updated ice sheet configurations do “a very good job” of reproducing the patterns observed in the proxy records.

“According to these models, it is the high pressure cells that are really important in steering winter storms, and in determining the shape and location of the transition zone,” said Oster. “Some models do hint at an increase in subtropical winter moisture, but we don’t see evidence of an enhanced summer monsoon.”

Given the prospect of continued global warming, there is no chance that this ancient weather pattern will return in foreseeable future. Curiously, however, a similar pattern re-emerges periodically during the warm phase of the El Ni?o-Southern Oscillation, which produces drier than normal winters in the Northwest and wetter than normal winters in the Southwest.

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The research was supported by National Science Foundation grants AGS1203701 and EAR0921134.

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90 thoughts on “Study finds massive climate change in North America before there was even an argument about it

  1. Here in the last chapter is a great example of how ludicrous the whole thing is.
    Given the prospect of continued global warming, there is no chance that this ancient weather pattern will return in foreseeable future.
    Notice the no chance in the foreseeable future. And then just a sentence later.
    Curiously, however, a similar pattern re-emerges periodically during the warm phase of the El Ni?o-Southern Oscillation, which produces drier than normal winters in the Northwest and wetter than normal winters in the Southwest.
    No chance and yet it happens. It is the blind leading the blind and they don’t even recognize it.

    • What this is saying is, during ICE AGES the West Coast is mainly DRY and warmer than the rest of North America.
      Geeze, as I freeze here on the East Coast well within the glacier zone in the past, it being often below zero, we have the same conditions today: the eastern half of all of North America is extremely cold while the west coast is warm and dry.

  2. Improves climate models developed to predict future rainfall patterns

    Why am I thinking of Australian desalination boondoggles?

  3. All I want for Easter is that the cAGW cultists live long enough for their grandchildren to beat them senseless with snowballs in Florida, and make them spend the night outside in the doghouse.

  4. “Given the prospect of continued global warming, there is no chance that this ancient weather pattern will return in foreseeable future.”
    Oh, you just had to spoil it, didn’t you. The agenda is alive and well.

  5. Yes, there has been massive climate change in North America before, and there will be again. Archaeologists who have studies the Anasazi (“Ancient Enemy” to the Navajo) have recorded their migration south into Mexico during climate change in the 12th and 13th centuries.

    Current opinion holds that the Ancestral Puebloans responded to pressure from Numic-speaking peoples moving onto the Colorado Plateau, as well as climate change that resulted in agricultural failures. The archaeological record indicates that it was not unusual for ancient Pueblo peoples to adapt to climatic change by changing residences and locations.

    http://en.wikipedia.org/wiki/Ancient_Pueblo_peoples#Migration_from_the_homeland

    • When I visited the 4 corners area last summer a Park ranger told me the local Indians (or whatever they call themselves now) claimed the ruins as their own and the government accepts that interpretation. I asked on what basis and he replied the locals said they are direct decedents. I asked about DNA tests on those ancients who are buried there and he said they weren’t allowed to test them.

      • Ever here of cultural continuity? It has been well established that the Hopi are the descendents of the Anasazi. Recently, it has been established the the O’odham are descendents of the Hohokam. Old Oraibi has been continuously inhabited since 1100 AD.

      • The ‘local Indians’ happen to be Utes and Mountain Utes. They most definitely are not descendents of the ‘ancient ones or Ancestral Puebloans’ (Anasazi is now considered derogatory to the Hopi and modern Pueblo Indians, that is it is no longer PC to use the terms.) I think there is a good deal of agreement that the modern day Pueblo Indians, located primarily along the Rio Grande in New Mexico are the descendents of the Ancestral Puebloans. To these are added the Zuni and Hopi. The Hopi in particular intrigue me because they have preserved so much of their historical culture and traditions. I would bet that there is a great deal that they could tell us ‘white folks’ about their history but probably never will as this history is interwoven in their oral history and religious beliefs – totally off-limits to outsiders.

      • It is part of the oral tradition of present day Pueblo Indians of northern New Mexico that their ancesters migrated from the Mesa Verde area centuries ago. This tradition was ignored by archaeologists until recently, when it has been taken seriously.

  6. “One of the smelliest proxies that they used is pollen preserved in ancient packrat middens.” Smelliest? – After how many thousands of years? The whole study stinks.

    • One has to dig through the fresh stuff to get to the fossilized stuff. If they are using it as a historical record of weather conditions then that implies that it is a layered type of material, lain down over many years. If the sites are still actively inhabited, then they might want to wear air masks. Guano fumes can be deadly – literally, I’ve heard.

  7. According to these models, it is the high pressure cells that are really important in steering winter storms
    1. Find some data
    2. Find some models that match the data
    3. Decide what in the models that match the data is the driving force.
    That all the other models must be wrong (by their evidence and logic) they simply gloss over. That these models may also be wrong, but match this particular curve fitting exercise because of other errors, they don’t seem to consider.
    Well at least they didn’t average a bunch of models together to get an result that fits their data. But it is still cherry picking to simply take the models that match the data for that specific time period in that specific geography and call them right.

  8. I know you guys do not like Wikipedia but for what it may be worth only as a means of comparison , whatever it could be worth for:
    Wikipedia
    “The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the northern United States, multiple times during Quaternary glacial epochs. It last covered most of northern North America between c. 95,000 and c. 20,000 years before the present day. At times, its southern margin included the modern sites of New York City and Chicago, and then followed quite precisely the present course of the Missouri River up to the northern slopes of the……..”
    and from BBC NEWS/Science /nature,,,,,,,, Friday 12 November, 2004, 12:54 GMT
    “Now, new fossil evidence suggests brown bears actually made their way through Canada more than 25,000 years ago, well before ice sealed their path. ………….
    Fossilised brown bear fragments dating back about 25,000 years have been uncovered in Alberta, Canada, for the first time………….
    The remains prove that brown bears must have made it through into mainland Canada before heavy ice closed the corridor from Beringia about 23,000 years ago. ….”
    ——————
    Apparently these brown bears must have made it successfully through the Canada, which at that time must have been covered mostly and under the Laurentide Ice Sheet.
    anyway just a point.
    cheers

    • Actually the Last Glacial Maximum was quite unusual in that the Cordilleran and Laurentide Icecaps coalesced for a while. There has normally been an ice-free corridor between them.
      Ever noticed that there is quite often a snow-free zone on the prairies just east of the Rockies? Same phenomenon, rain-shadow and föhn effect.

  9. And I thout this was a good argument.
    Signs of 400-Year-Old Human-Produced Air Pollution Found in Andean Ice Cap
    Feb 10, 2015 by Sci-News

  10. Wow, so it’s a 50/50 bet. You need complex computer models to arrive at that number? I wonder what the error bars are around that estimate and the confidence levels – and do 97% of client scientists agree?

    • “Wow, so it’s a 50/50 bet.”
      Notice also that it is stated negatively, ‘put the odds that the American Southwest is headed into a 30-year “mega drought” at 50/50.’ It is just as likely (50/50) that the SW will not experience serious drought (assumed definition of ‘mega drought’ – I’m not a climate scientist) in the next 30 years. Climate scientist papers must include DRAMA!

    • Google Laurentide Ice Sheet and you’ll get a great many more maps, some of which actually agree with the geology of the region where I live. This one doesn’t.
      If interested look up “The Driftless Region” and see where it is and what it means.

      • It does not mean that the “driftless” area was surrounded by ice (N,S,E,W) at the same moment. And it does not mean that the map (above) does not represent the situation at some moment.

      • John,
        You are correct. The map you provided supports your post regarding an ice free corridor and not necessary the fullest extent of ice cover.
        The Driftless region was indeed ice free to the south most if not all of the last ice age.

    • Hello….Brown bears in Alberta Canada ~25K years ago. not the same as per you above mentioning. And these bears did not go any south than that.
      Ok, if you say no Laurentide Ice sheet in Alberta at that time, and Alberta a brown bear paradise at that time, I will not complain.:-)
      cheers

    • Hultquist, take a good look at the map. You have an ice free Rocky Mountain chain in Canada during the ice age. Interesting

    • Two major theories (Wegener’s continental drift and Milankovic’s planetary cycles) gained general acceptance since 1950s.
      And now there is some evidence that the rapid de-glaciations follow changes in the rate of the N. Atlantic’s tectonic plates shift.

  11. Never see these patterns again? Given that global warming is at most 3K more likely 1k and the ice ages were -6-8k from today. Global warming is hardly going to hold back the ice age patterns. The milankovitch cycles will still occur with or without global warming

  12. Somewhere in my dim and distant memory I read a report that the Laurentide Ice Sheet created an ice dam during its melting period. When the ice dam broke and released the water, this raised global sea levels about a metre or so. In the Mediterranean, the centre of civilisation at the time, this ‘flood’ carried Noah’s Ark up into the hills.

  13. “A team of scientists from Vanderbilt and Stanford universities have created the first comprehensive map of the topsy-turvy climate of the period”
    Actually it is the othar way around. Since it is glacial climate 90% of the time and interglacial 10%, its the glacial climate that is normal and the present that is topsy-turvy.
    By the way that computer medal is a bit off (as usual). While much of the southwest was certainly wetter than at present there is evidence that the Los Angeles basin was, if anything, slightly drier than today.

  14. Reblogged this on CraigM350 and commented:
    The models are woeful, so let’s use the models. Love also the circular thinking about the jetstream for the Laurentide. Clue for them…look up! 🙂

  15. First, the Laurentide ice-sheet did not go over the Rockies as depicted by Vanderbilt and J. Oster.
    Second, when CO2 was as low as 185 ppm 21,000 years ago, you are not getting any conifer forests growing in the US southwest or in any area that does not get more than 50 inches of rain per year like the US southeast, the Amazon and the African equatorial did at the time. C3 trees and bushes need extensive rainfall to grow properly with CO2 levels this low.
    Run a climate model, publish a paper. That is what this science is about now.

    • Well at least they are trying to match models to the data.
      “you are not getting any conifer forests growing in the US southwest or in any area that does not get more than 50 inches of rain per year”
      The southwest did get much more precipitation during glacial periods, the evidence for this comes from lacustrian layers, and that for vegetation cover from packrat middens. The question for the study was whether the precipitation supporting the conifer forests was because of high-pressure displaced jet stream or because of tropical moisture trap.

  16. To prove climate “change” is dangerous isn’t it necessary to first prove that climate “stasis” is possible ?

    • We don’t seem to have any historic data in the proxy records that supports the existence of any periods of prolonged stasis. So if a static climate could be achieved, it would be the first truly UNPRECEDENTED event in a long, long while.

  17. All that is required for climate stasis to be possible is for you to pay a huge amount of tax money to someone else. If you do not make this payment, climate stasis is not possible.
    this has been proven repeatedly throughout history, where sacrifices have been made at the temple to ensure the gods will remain happy and bless us with continued climate stasis.
    It is only when we fail to make these sacrifices that the gods turn angry and the climate changes for the worse. We get extreme weather, super-storms and mega droughts.
    We know this to be true because throughout history we have had extreme weather, super-storms and mega droughts. Only now have we finally understood the solution is greater sacrifice.

  18. Given the prospect of continued global warming, there is no chance that this ancient weather pattern will return in foreseeable future.
    From the study which makes this study null and void.

  19. Interesting.
    If it was drier near the ice sheets, and wetter further south, this rather suggests that the low-pressure systems were tracking further south than they do today. Is this how/why ice sheets grow?
    Is there a jet-stream mechanism that keeps low-pressures further south, and stops them spinning great hunks of warm air into the higher latitudes? Much of the UK’s warm weather is gusts of tropical air, provided by deep depressions. Take that away and the UK would be very cold, no matter what the Atlantic Conveyer and Atlantic temperatures were doing.
    So are Ice Ages characterised by a stratification in climate, with the tropics keeping all their heat to themselves, and thus allowing the poles to cool?
    R

  20. Nice. Last week “super” was invoked as in super-greenhouse effect. This time someone broke out “Mega” waiting to hear “hyper” something or other. Overblown rhetoric is fun.

  21. 50:50 results are considered scientifically important results?
    Models are run to match the records. 111 errors out 114 are good enough to satisfy the “scientific” label of CAGW. I’ll be impressed when something unknown is predicted and then found.

    • AGW needs no further falsification. It was born falsified.
      There is not a shred of evidence in support of the hypothesis of man’made global warming. Humans have caused local warming in some places, as for instance central cities which used to be desert, swamp, woods or grassland. But human activities also arguably cool the planet, so even the sign of our net effect is not known, but is sure in any case to have been negligible so far.
      Please, as asked previously, present what you consider to be the evidence showing that AGW exists, with a high degree of probability. You could win a Nobel Prize for doing what IPCC & national science academies have not been able to do. Thanks.

      • OK. So the first response to my question is an answer that doesn’t stand up in the Court of Reason: “AGW needs no further falsification. It was born falsified.”
        The answer to your question ‘what is the evidence for AGW” is that the evidence is overwhelming. If you wish to read it, go to the IPCC 5th Assessment, which summarizes 10,000 papers by peer-reviewed independent researchers from all over the world.
        Have you read this evidence?

      • warrenpound:
        #######
        Have you read it? What we want is for someone like you to briefly summarize the main evidence in support of AGW. No one has so far. No one never will. You are fooling no one with your dodges.

      • There is not a shred of evidence demonstrating AGW in any IPCC report or anywhere else.
        If you know of some, please, for the umpteenth time, present it. If you imagine it to be overwhelming, that should be easy for you.
        Thanks.

      • @warrenlb:
        Planet Earth is busy falsifying the IPCC, AR-1 through AR-5.
        You don’t like it? Tell the planet she’s wrong.
        The rest of us will laugh at you.

      • As I said, the hypothesis was born falsified, in its revived 1980s version.
        Callender recognized that his hypothesis was falsified in the early ´60s by pronounced cold, to his disappointment, since in the ´30s he hoped that man-made global warming would benefit humanity & other living things.
        Despite rapidly rising CO2, the world cooled from the late ´40s to late ´70s. Some slight warming might have occurred from then until the late ´90s, accidentally coinciding with a continued rise in CO2. Since then, for going on 20 years, the world has stopped warming & appears to be cooling, again despite a further rise in CO2 levels.
        Thus was AGW stillborn. Abundant other evidence supports the same conclusion.
        QED.

      • Warren pound,
        The consensus opinion on you is that you will never present here, in your own words, the most compelling evidence of AGW.
        Now, all you need to do is just present one item of evidence that supports the AGW hypothesis, just one, that’s all, and we are wrong.

  22. With the conditions described in the article being the norm of that epoch, How can we dictate what the norm should be now? The scary statistics of this Carbon-crazy diversion into a climate twilight zone are based on anomalies… from what norms? to pick out a century or two when climate was at a different juncture and focus on that as a norm, is like choosing one or two minutes of a year to calculate against the anomalous variations in the remaining minutes.
    I see optimism in human ingenuity and adaptability. We need to get back on the main road of science and put off predicting the future for a while, to take care of completely understanding the present.
    I sure don’t doubt climate change, but I seriously doubt any ability to predict it’s course.

  23. These people have no knowledge of even basic natural history. 21,000 years ago, much of Utah was covered by Lake Bonneville, which was 1,000 feet deep and larger than Lake Michigan. (the Great Salt Lake is a very small remnant) And it was far from the only great lake in the region – there were lakes covering large portions of Nevada as well.
    So ya think it was a bit wetter then than now?
    btw, it’s kind of funny to see warrenlib preach the True Faith of the IPCC. Warren, you’ll do better by finding some organization that isn’t run by a self-aggrandizing sex offender. Trust me on that one.

      • As always, Stealey has no ability to falsify AGW or its evidence, and certainly not this study, which is the question at hand.

      • As always, Warren the Numpty doesn’t understand. The planet herself is busy falsifying AR-1 thru AR-5.
        So, who should we believe? warrenlb? Or Planet Earth?
        Because one of them has to be wrong.

      • So far, still no evidence presented by Mr. #. Rest assured that he never will present any such evidence.
        One cannot escape the impression that pound lacks sufficient grasp of the matter to be able to articulate the science that he claims as support for AGW.

      • While AGW theoretically exists, it has not been able to make it’s presence felt in nearly 20 years. I suggest that your favorite culprit of climate change might actually be the ant trying to move the elephant out of the room.

      • Where is the evidence that AGW is driving the climate? You have been asked numerous times now, and all you have is dodge, in reply. Give us an example with details, Warren.
        You a Los Angeles Dodger fan?

    • So ya think it was a bit wetter then than now?

      You’re right about the lakes. There’s a map at http://gec.cr.usgs.gov/projects/paleo_hyd/paleolakes.shtml However in a addition to probably being wetter back then, it was also presumably colder — there was, after all, a major glaciation in progress. That probably means evaporation was lower. Cut back on the evaporation enough and wait a few millenia and even the meager flow of the Truckee, Walker, Owens, Humboldt, Virgin Rivers is probably going to fill up all the low spots in the Great Basin.

  24. It was an interesting read….. until Climatodrastic Global Warming was invoked to justify the implausibly short sighted statement “….there is no chance that this ancient weather pattern will return in foreseeable future.” Sounds similar to other hyperbole assertions like“Children won’t know what snow is!”, doesn’t it?
    The climate models do not reflect reality: 18 years of no warming while atmospheric CO2 has continued its ploddingly regular annual increases. They are unsuitable for forecasting, by any reasonable standard. Even their ‘hind casting’ outputs are little better than ‘hind cast’ products produced in ‘rest rooms’ world wide.

  25. Mostly, these folks seem to be trying to describe the climate of Western North America during the last glacial period. Seems a reasonable undertaking. And nothing they are working with seems objectionable.
    OK then, very possibly we had arctic tundra in regions adjacent to the Laurentide ice sheet and cool, reasonably well watered forests of conifers South of the tundra. Seems pretty reasonable, no? (At least if you ignore the existence of literally hundreds of substantial mountain ranges and deep intermountaine valleys that probably have different climates at different elevations).
    As for climate models When the researchers compared their results with the output of a number of climate models, ‘they found that several of the newer models … that use updated ice sheet configurations do “a very good job” of reproducing the patterns observed in the proxy records.’ No offense to the modelers, but if climate science is so damn rigorous, why don’t ALL the models do a good job? If you fire shots pretty much at random, you’re bound to hit a target every now and then. That’s luck, not science.

  26. “Cold air from Canada and moisture from the Gulf of Mexico will clash to bring a significant winter storm with accumulating snow and an icy mix in a large part of the South at midweek.”
    It will also be more moisture in California.

  27. I’m sorry, but I remain skeptical that the degree of accuracy they are claiming in these models is available from proxy data. You may be able to get a general trend but I would be surprised if it was useful for calculating anything to any useful degree of accuracy.

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