Ancient cold period could provide clues about future climate change

This is the room in the cave where the scientists obtained the stalagmite used in the research CREDIT Raf Rios

This is the room in the cave where the scientists obtained the stalagmite used in the research CREDIT Raf Rios

From the UNIVERSITY OF TEXAS AT AUSTIN

Researchers at The University of Texas at Austin have found that a well-known period of abrupt climate change 12,000 years ago occurred rapidly in northern latitudes but much more gradually in equatorial regions, a discovery that could prove important for understanding and responding to future climate change.

The research, published Sept. 2 in Nature Communications, focuses on the Younger Dryas, a cooling period that started when the North Atlantic Current, an ocean current, stopped circulating. The event caused Earth’s northern hemisphere to enter into a deep chill, with temperatures in Greenland dropping by approximately 18 degrees Fahrenheit in less than a decade.

The event also caused rainfall to decrease in places as far away as the Philippines. However, whereas temperatures in Greenland responded quickly to the ocean current shutdown and subsequent reboot 1,000 years later, it took hundreds of years for rainfall in the Philippines to be affected and to recover.

“We found that the temperature in Greenland is like a small ship that you can stop and turn quickly because of the influence of sea ice in the region, while rainfall in the tropics is like a big ship that takes a long time to course correct,” said Jud Partin, a research associate at the University of Texas Institute for Geophysics (UTIG) who led the study.

The changes in temperature and rainfall are linked to a common cause: the slowdown of the ocean currents in the North Atlantic, which affect climate and temperature as they move warm water from the Gulf of Mexico toward the Arctic. As the world warmed after the last ice age, glaciers melted and diluted northern seawater with freshwater. The resulting change in ocean water density disrupted the current and, in effect, the climate, causing a period of global cooling.

The event also inspired the premise of the 2004 disaster flick “The Day After Tomorrow,” which exaggerates the speed and strength of the cooling by depicting the planet entering an ice age in a matter of weeks after the ocean current collapses.

Although other studies well document the changes in temperature and precipitation around the world, this new study concludes that these changes do not occur or recover at the same rate, as had been previously assumed.

Understanding the relationship between temperature and precipitation in the wake of climate change is particularly important because it previews what could happen if the planet’s ice sheets continue to lose mass and add freshwater to the North Atlantic.

At a conference in Paris during July of more than 2,000 climate scientists, the potential collapse of the North Atlantic Current’s circulation was identified as a possible catastrophic consequence of climate change.

“A slowdown of the ocean circulation is a double-edged sword: If we see some temperature changes associated it … and somehow are quick to act and alleviate the change, then we have the potential to stop it before it impacts rainfall globally,” Partin said. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”

The researchers discovered how rainfall in the Philippines was affected by the Younger Dryas event by analyzing minerals deposited in a stalagmite growing from the floor of a cave in Puerto Princesa Subterranean River National Park in Palawan. They found that it took more than 550 years for drought conditions to reach their full extent in the region, and about 450 years to return to pre-Younger Dryas levels after the North Atlantic Current began circulating again. The record suggests rainfall was about 25 percent lower than present levels during the cold snap.

They then compared these findings with previously published ice core data. According to these records, it took a decade or less for temperatures in Greenland to drop by approximately 18 degrees Fahrenheit once the current collapsed and about 40 years to rebound after it returned.

Partin conducted the work with UTIG Director Terry Quinn and collaborators from the National Taiwan University and the University of the Philippines-Diliman. UTIG is a research unit of The University of Texas at Austin Jackson School of Geosciences.

Computational models of the Younger Dryas temperature and precipitation also provided insight into the role of sea ice in Greenland’s abrupt temperature change.

“Sea ice around Greenland acts as a ‘switch,’ causing that region to respond more quickly than the rest of the planet does by insulating the air from heat stored in the deep ocean,” said Yuko Okumura, a UTIG research associate and a co-author on the study.

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The study was funded by a grant from the National Science Foundation.

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166 thoughts on “Ancient cold period could provide clues about future climate change

  1. So it happened naturally before, but man is causing it now, and we have the power to stop it. Pull the other one.

    • They studied temperature and precipitation. Hopefully, they got that bit right. The rest is pure speculation using models based on … Dinsdale’s rules. So of course they found what they found. There was nothing else there (ie, in the models) to find.

    • And research identified the cause then, and research has identified the cause in the industrial era…mans burning of fossil fuels, the resulting 40% increase in atmospheric CO2, and a corresponding increase in the greenhouse effect. Well established science.

      • warrenlb
        Appeals to authority are not science. There is no published scientific research that has proven the existence or magnitude of anthropogenic warming. If established dogmatic theories fail to match observations from the real world, nothing has been established. Furthermore, catweazle666 hasn’t made anything up, his claim refutes a wild assertion that has yet to be proven. The onus is not on him/her to prove that CAGW is unproven.

      • @rob Morrw
        Absolute baloney. NASA and every Science Academy confirms AGW. Evidence you’ll find on the NASA link I gave you—unless you are illiterate. When Science concludes AGW, it’s up to a Science D**r to publish his contradictory evidence, which none have done.

      • Warren,

        Why do you keep referring to supposed sources which all here know do not say what you claim?

        If you imagine that there are actual data supporting the repeatedly falsified hypothesis of AGW, please present them here. If the data are so abundant, why can’t you ever do as asked over an over again and state what they are, yourself?

        Your scientific betters here have shown you evidence after evidence against the failed hypothesis of AGW, for which facts you have no answer. What makes you so anti-science as to reject incontrovertible evidence against AGW while being unable to provide a single shred of real data in support of the fantasy?

        Please start by explaining why the planet cooled so strongly all during the first 32 years of postwar CO2 rise. Next kindly tell us why the planet has stopped warming (as it did briefly in the 1980s and ’90s) and is once again cooling despite even more rapid gains in this century.

        Thanks.

      • warrenlb,
        The webage you linked to offers no proof, as proof is defined in a scientific context. The first two items of AGW confirmation on the “evidence” page are nothing more than appeals to authority:

        “Scientific evidence for warming of the climate system is unequivocal.”
        – Intergovernmental Panel on Climate Change
        Scientific Consensus
        “Ninety-seven percent of climate scientists agree that…” blah blah

        The rest of the page also contains no evidence, as evidence is defined. Evidence of the validity of a theory tends to come from observation. Since CAGW theories are incapable of producing a unique forecasting result, they have very little predictive power. And the forecasts produced by averaging of CAGW model outputs have failed to match observation. Perhaps you would be kind to point out the proof that I am clearly too inept to find.

      • @Gloria Swansong
        So you too are taking the position of the monkey covering it’s eyes to make sure it can’t see the evidence, so it can claim it’s not there. You do not impress.

      • Warren,

        For the umpteenth time, there are no actual data in evidence to support your baseless assertion of AGW.

        Please post them here is you have them. You keep your eyes firmly shut to reality.

        Why won’t you reply to the indisputable fact that rising CO2 for most of the time since 1945 has been associated with global cooling rather than warming?

      • warrenlb: “Select ‘Facts’ then ‘Evidence’ on the menu.”

        Warren old bean, you wouldn’t recognise a fact if it scampered under your foetid, slimy bridge, leapt up, and sank its fangs into your snout!

      • warrenlb says:

        NASA and every Science Academy confirms AGW.

        As usual, warrenlb misrepresents the issue. There is indirect evidence that anthropogenic global warming exists, and like many commenters here, I accept that AGW is occurring.

        But it is simply too minuscule to measure. That’s why there are no empirical, testable measurements of AGW. There’s a Nobel Prize waiting for the first person who produces replicable, verifiable, accurate data that directly measures the fraction of man-made global warming (MMGW) out of total global warming from all sources, including the planet’s recovery from the LIA.

        But saying some ‘authority’ or other “confirms AGW” is meaningless.

        Is AGW 50% of all global warming? We don’t know.

        Is AGW 3% of all global warming? We don’t know.

        Is AGW 0.005% of all global warming? We don’t know!

        We just don’t know. At all. But the fact that MMGW is too small to measure indicates that it isn’t a problem. And the fact that there has been no global warming at all for almost twenty years is pretty conclusive evidence that at current concentrations, CO2 is not the culprit that the alarmist crowd claims.

        Honest scientists admit it when the facts contradict their conjectures. The only honest kind of scientists are skeptics. Draw your own conclusions…

      • DB,

        IMO AGW hasn’t been observed in the real climate system because, if it exists, it is promptly counteracted by negative feedbacks.

        Now, researchers recently claimed to have observed the GHE from CO2, but their work is marred by reliance on models. But for the sake of argument, even if increased CO2 is from human activity, and this observation/model reflects reality, the fact is that global temperature has not warmed despite lots more CO2 in the air.

      • @Gloria Swansong and DBStealey.
        I don’t buy the snake oil you’re selling. When amateurs start making claims that contradict peer-reviewed science and claim they ‘can’t see the evidence’ that all peer-reviewed science sees, and all the world’s science institutions confirm, it’s time to hold on to one’s wallet.

      • warrenlb
        Sorry, I did use “proof” incorrectly. Thanks for the help. Now if you could point to the link that shows evidence of theory matching observation that would be super. Oh, and you had better post another link that shows natural forcings are net zero at any time scale, which is a requirement of “consensus” climate theories. Saying that they are zero over long time scales and omitting them entirely from models is the same thing. Every reader here knows that your “evidence”, which you may or may not have even read, let alone understand, is entirely reliant on models which haven’t been validated by observation.

      • and warren,
        You haven’t quoted any peer reviewed research in this thread. Instead you posted a link to NASA’s main climate page as evidence, and you are calling your fellow posters amateurs?

      • warrenlb,

        All you’ve done is make another baseless assertion. But then, you’re an amateur.

        Wake me when you find an empirical, testable measurement quantifying MMGW. Until you can do that, you’ve got nothin’ but baseless assertions, and your endless appeals to bought-and-paid-for ‘authorities.

        So enough deflecting and misrepresenting. Either post a measurement quantifying AGW, or admit that all you’ve got is a conjecture.

      • dbstealey: “Either post a measurement quantifying AGW, or admit that all you’ve got is a conjecture.”

        “Conjecture”? As good as that?

        Downright mendacity would be my take.

        And stupid with it.

      • warrenlb
        September 3, 2015 at 3:47 pm

        Peer review doesn’t exist in “climate science” and doesn’t work anyway. It’s all pal review and utter garbage.

        If you imagine that there really is evidence for AGW, why can’t you state it in simple, declarative sentences?

        Why can’t you reply to the actual, observed facts which show the hypothesis of AGW false?

        What makes you think I’m an “amateur”? And even if I were, many of the greatest scientists in history were amateurs. Your appeal to bogus authority is laughable.

        The charlatan, snake oil salesman Michael Mann isn’t a pimple on the posterior of a real scientist, like Freeman Dyson, if the the good Dr. Dyson, heir to Einstein, will forgive such a rude comparison.

      • catweazle666,

        It’s hard to argue with your conclusion that scientists are mendacious. I don’t really think they’re stupid, though.

        Anyway, a conjecture is the first step in the hierarchy: Conjecture, Hypothesis, Theory, Law.

        It’s only the starting point; an opinion. A conjecture is an educated guess, nothing more. In general this whole debate is over the conjecture that rising CO2 is the cause of global warming.

        The problem that warrenlb and his alarmist folks have is that all 4 of those levels of certainty (not that anything in science is certain) is that each of them must be capable of making repeated, accurate predictions. The higher in the scientific hierarchy, the more accurate the predictions. But they all have in common the requirement that they must be able to make accurate predictions. And not just once; the spike in global T in 1997 was a one-off event. They have been wrong ever since.

        The CO2=cAGW conjecture has never been able to make repeated, accurate predictions. Their central assertion, which forms the basis for all climate alarmism, is the prediction that rising CO2 will cause runaway global warming.

        That has not happened. In fact, despite steadily rising CO2, there has not been any global warming for the past 18 years, seven months. At what point will they throw in the towel, and admit that their original conjecture has been falsified? Some scientists are already saying that. But there aren’t enough of them yet.

        In any other scientific discipline, the abject failure to make any accurate predictions for almost twenty years would falsify a conjecture. Normally, scientists are then supposed to go back and try to understand where they went wrong: why has their conjecture failed so spectacularly?

        But that would require them to admit that at current concentrations, rising CO2 causes no measurable global warming. They would have to admit that they were just plain wrong. But since CO2=AGW is their central premise, and the source of the “climate studies” federal money hose and their job security, they have apparently decided that mendacity is preferable to the alternatives.

        Also, by now they would realize that such an admission would be a climbdown from their absolute certainty that their original conjecture was right — and at this point, that’s what it would be: a climbdown. They have waited far too long; the evidence keeps piling up against them.

        Instead, they should have gone with Dr. Phil Jones’ statement that if no global warming resumed for 15 years, that their conjecture was wrong. But $1 billion+ in annual grant money shouts a lot louder than the skeptics of dangerous man-made global warming. And of course the media plays a part in what is now simply a hoax.

        So now they’ve switched gears. They rely on warrenlb’s ‘Appeal to Authority’ logical fallacy, and on baseless assertions, and they use other non-scientific arguments in place of the only evidence that would rescue their conjecture: verifiable measurements of AGW, and/or repeated, accurate predictions. But they don’t have any real world evidence. All they have are their repeated assertions that they’re right.

        I don’t think they’re stupid at all. They know what they’re doing. Yes, it’s mendacious, and it harms science in the long term. I used to believe that NASA was above reproach. I used to look up to all priests, and especially the Pope. I used to believe that cops were honest.

        But like Lily Tomlin famously said: No matter how cynical you get, it is impossible to keep up.

      • dbstealey: “I don’t think they’re stupid at all. They know what they’re doing.”

        If they have effectively bet their entire credibility on a prediction that is as much of a hostage to fortune as global temperature, they are not very bright, no matter how intelligent they are in their narrow field.

        Do not equate academic excellence with non-stupidity, I have known a number of incredibly academically intelligent individuals with enough PhDs and professorships to paper a decent sized living room who are truly not fit out on their own. Some of their life choices demonstrate levels of truly Olympian stupidity, in fact.

      • DB,

        The conjecture was born falsified. The cooling after WWII despite rapidly rising CO2 falsified the AGW (thought beneficial) hypothesis proposed in the 1930s. The cooling of 1945 to 1977 also pre-falsified the AGW conjecture spewed in the 1980s and ’90s.

      • Gloria,

        You’re right about the conjecture being falsified, but the man-made global warming narrative was on the back burner for a long time.

        Like a lot of folks, I began to pay attention when the great El Nino of 1997 caused global T to rise very fast. I tried to keep an open mind, but that event was not followed in later years. CO2 kept rising, but temperatures didn’t. And then Anthony Watts started investigating the government’s Surface Station network, which showed that its numbers were simply unreliable. They were giving us tenth and hundredth of a degree temperature records, when a majority of the stations were off by 2º – 5º or more.

        I worked in a Metrology lab, and we recieved all the current literature, gratis, from instrument vendors. When I began that job in 1973 global cooling was in the news. That didn’t happen, either. Now my attitude is, ‘I’ll believe it when I see it’, whether it’s cooling or warming. For almost 20 years now, it’s been neither.

        The big difference now is the really huge amount of money propping up the scare. It wasn’t anything like that in the ’70’s. I have no doubt that if that money flow was cut off, the ‘dangerous man-made global warming’ scare would promptly disappear. Because it’s all based on smoke, mirrors, assertions, and endless appeals to bought-and-paid-for ‘authorities’.

      • DB,

        In the 1970s, global cooling had already happened for three decades. The issue was whether the world would continue cooling.

        The AGW conjecture of the 1930s had been shown false by the pronounced post-war cooling, yet given the short memory of AGW proponents, the already falsified proposition was revived in the 1980s. But now alleged man-made warming was considered scary rather than beneficial.

        As I’ve mentioned before, a leading proponent of beneficial AGW in the 1930s, Callendar, had to admit that his conjecture was falsified by the severe cold of the 1960s, particularly the winter of 1962.

        But Hansen, et al, not being climatologists, either ignored or didn’t know about the extreme cold of the ’60s and ’70s. How they could have missed the many reports by government scientists in the 1970s predicting more and worse cold, however, I don’t know.

      • And of course you’re right that now a vast, global conspiracy and academic-government-Green-industrial complex is supported by the AGW fantasy.

  2. I wonder if the Single Stalagmite is as telling as the Single YAD tree and if it has a bladed end?
    There is a definite problem where the sampling size = 1 or the sampling area = 1

    • “There is a definite problem where the sampling size = 1 or the sampling area = 1”

      Certainly makes it easier to prove a point, as it eliminates any nasty sample correlation issues when N>1

    • It is called the New Statistics of Climate Seance and it involves a round table of half spiritualists and the other half climate seanceists with the latter being funded by huge grants from NSF, DOE, NOAA, NASA, etc., etc. of which they impart a minuscule amount of the grants (say a $million or two which is in the accounting uncertainty of the Green $Blob) to the spiritualists and their publicity agents.
      All it takes is one Ouija board for each scientific conclusion. Samples of size 1 are most appropriate for this “Round Table Group”.

      • the Church of Scientology
        =====================
        the Church of Scientology is tax exempt no less. You are likely not. So who has the last laugh?

        if the government was giving away $1 million dollars for every one armed, one legged person, within a very short time 1/2 the country would be cutting off arms and legs.

      • I used to smoke 10 packs of cigarettes a day till I got lung cancer. Had half of my lungs removed…So now i’ve cut my smoking in half and only smoke 5 packs a day. Works out pretty good too. Saved 1/2 the money.

  3. “A slowdown of the ocean circulation is a double-edged sword: If we see some temperature changes associated it … and somehow are quick to act and alleviate the change, then we have the potential to stop it before it impacts rainfall globally,” Partin said. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”

    Climate science can now control ocean currents.

    • And they say nothing about the drainage of the lake Agassiz into Hudson bay, which stopped the North Atlantic current.

      • More likely via what is now St. Lawrence seaway. The scour was powerful, and the extent of seafloor sediment fan supports the hypothesis. No Lake Agassiz, no possibility of another such event. Melting and calving glaciers are just too slow.

      • There really isn’t much support for the idea that freshwater flows from the Great Lakes or Greenland actually suppressed the NAC. That was a popular idea decades ago, much less so now. For instance see Jim Steele’s recent article on the “Arctic Iris Effect” here on WUWT.

      • That’s still the standard explanation for the cause of the YD (from 2008):

        http://www.ncdc.noaa.gov/paleo/abrupt/data4.html

        What caused the Younger Dryas?

        The Younger Dryas occurred during the transition from the last glacial period into the present interglacial (the Holocene). During this time, the continental ice sheets were rapidly melting and adding freshwater to the North Atlantic. Figure 6 shows the reconstructed freshwater flux from the melting Laurentide ice sheet through the St. Lawrence River. Just prior to the Younger Dryas, meltwater fluxes into the North Atlantic increased dramatically. In addition, there was probably a short-lived period of particularly high freshwater flux about 13,000 years ago that is not shown in this figure, resulting from a large discharge of freshwater from a glacial lake in North America. Scientists have hypothesized that meltwater floods reduced the salinity and density of the surface ocean in the North Atlantic, causing a reduction in the ocean’s thermohaline circulation and climate changes around the world. Eventually, as the meltwater flux abated, the thermohaline circulation strengthened again and climate recovered.

        The record from Dome C in Antarctica supports this explanation. If the thermohaline circulation were to slow, less heat would be transported from the South Atlantic to the North Atlantic (Crowley, 1992; Broecker, 1998). This would cause the South Atlantic to warm and the North Atlantic to cool. This pattern, sometimes called the “bipolar see-saw”, is observable when comparing the GISP2 and Dome C records for the Younger Dryas.

        Notice the second period of large freshwater discharge following the Younger Dryas in Figure 6. Interestingly, this discharge did not cause a second major climate change similar to the Younger Dryas. One possible explanation for this is that, after the Younger Dryas, the thermohaline circulation had become more vigorous as the climate finally entered the interglacial. A vigorous thermohaline circulation might be less susceptible to freshwater discharges.
        Some important datasets related to the Younger Dryas:

        Alley (2000), Temperature and accumulation from the GISP2 ice core in Greenland
        Hughen et al. (2000), Sediment grayscale from core PL07-58PC in the Cariaco Basin
        Lea et al (2003), Sea surface temperature in the Cariaco Basin inferred from Mg/Ca of forams
        Wang et al. (2001), δ18O measurements from Hulu Cave in China
        EPICA Community Members (2004), δD measurements from the Dome C ice core in Antarctica

      • Duster (@6:55) gets it right. There were many outlets for the water coming off the ice as it melted. Two that frequently get lost are : The Columbia River on the west coast and, the Mohawk/Hudson on the east coast.
        For the first search for: Missoula Floods
        For the second search for: Glacial Lake Iroquois

        Other flows were north to the Arctic Ocean and south to the Gulf of Mexico.

      • err? theres a lake up that way somewhere growing very large , I read about it some yrs ago
        its swamping towns n farms
        I thought it was Agazziz reforming?
        anyone else know of it?

      • Trouble is, as Berenyi Peter has pointed out many times and Wallace Broecker would likely now agree, the thermohaline circulation cannot be a heat engine. The thermohaline circulation may not even exist in any form remotely like the fanciful “conveyor belt”.

  4. and somehow are quick to act and alleviate the change, then we have the potential to stop it…

    I’m investing heavy in Evinrude/Johnson

  5. If climate scientists think they can somehow control the thermohaline circulation of the oceans, then that makes about as much sense as their ability to control the earth’s volcanic activity. The ego thinks it can do a great many things, but there is a distinct line between reality and fantasy, except for the deluded.

  6. l think Paris and european climate science needs to worry far more about a shut down of the Westerly air flow across europe then it does about a shut down of the North Atlantic drift. l really do think that climate science is barking up the wrong tree . When it try’s to pin major climate change largely down to the ocean currents.

    • “…to pin major climate change largely down to the ocean currents”

      Did I misunderstand? I could see ocean currents causing major climate change, but I just can’t wrap my head around 0.8C over 150 years changing ocean currents enough to matter?

      • Where l think climate science are getting it wrong is that it believes solely changes to the ocean currents are what causes changes to the weather. l think there wrong, Am convinced that long term changes to the weather are also a major cause of change to the ocean currents. Because is climate science suggesting that the North Atlantic drift shut down during the whole of the ice age.?

      • “…convinced that long term changes to the weather are also a major cause of change to the ocean currents.”

        Chicken & egg? I find the earth’s climate and our Sun very interesting, The less you know, the simpler it appears.

        I truly wish that climate science was taken seriously. I feel the next decade will be the decider, but I’m pretty convinced that a few ppm of CO2 is not the driver they’re looking for.

      • Climate science reminds me of Psychoanalysis. Lots of great sounding theories that make tons of sense logically. But after 100 years of careful study, all will prove worthless.

  7. The total daily contribution to the surface mass balance from the entire ice sheet (blue line, Gt/day). Bottom: The accumulated surface mass balance from September 1st to now (blue line, Gt) and the season 2011-12 (red) which had very high summer melt in Greenland. For comparison, the mean curve from the period 1990-2013 is shown (dark grey). The same calendar day in each of the 24 years (in the period 1990-2013) will have its own value. These differences from year to year are illustrated by the light grey band. For each calendar day, however, the lowest and highest values of the 24 years have been left out.

    • Ren, I’ve pointed out to you before that without a link to your data you are just jerking our chain. I note that you have very carefully arranged things so that nobody can verify or check your work.

      Please jump aboard the 21st century and start citing your data sources. For all we know, you just made this up on your computer.

      w.

      • Thanks, ab. As I read it the net Greenland ice sheet accumulation in the worst year (red line, lower plot) was zero … and every year except that the ice sheet has gained mass.

        Is that correct?

        w.

      • ren, here’s why sources are important. It turns out that the graph you posted is the result of a model. Not observational results. A model.

        Now, I’m not saying that means that the model is wrong, and it’s clearly not useless … but because you didn’t tell folks it was model results and you didn’t provide a link, you’ve unintentionally misled folks.

        Bad plan. Folks don’t like that.

        w.

  8. Yesterdays article on the “Arctic Iris Effect” gives a completely different take on how these events occur. Unless what they’re talking about here is a different circumstance.

    • It is different. You are correct. A fresh water pulse sufficient to shut off the NA thermohaline circulation must be vast and very abrupt. paleo lake Agassiz suffices; breached ice dams. Nothing in today’s world does. Not even remotely.

      • And there is no evidence Lake Agassiz did so either. The freshwater shut down is based on the incorrect ocean conveyor belt that suggests changes in buoyancy drives poleward heat transport. That idea is falling apart in most circles except Rhamstorf and Mann’s. As Lozier (2010) wrote, “the conveyor-belt model no longer serves the community well—not because it is a gross oversimplification but because it ignores crucial structure and mechanics of the ocean’s intricate global overturning

  9. “They then compared these findings with previously published ice core data. According to these records, it took a decade or less for temperatures in Greenland to drop by approximately 18 degrees Fahrenheit once the current collapsed”
    This would seem to present more of a problem than global warming.

  10. While those geniuses are manipulating ocean currents, I wish they’d go ahead and do something about Earth’s orbital velocity, because I’m getting really tired of leap years.

    • Plus several shed-loads.
      Fortunately my red wine was on the side, not to my lips, so I don’t need a new computer!

      Auto

  11. As the world warmed after the last ice age, glaciers melted and diluted northern seawater with freshwater. The resulting change in ocean water density disrupted the current
    =======
    yep, that works

    • This map helps to make my point in a earlier post.
      They are claiming that the melting of all this ice is what caused the North Atlantic drift to shut down.
      So if that is the case, than clearly the North Atlantic drift must have been running during the ice age.
      So if the cause of the cold during the ice age was not the shutting down of the North Atlantic drift, then what was.!

      • Global warming causes global cooling – i.e. they will be blaming any future cooling on global warming, when in fact, global warming and cooling have been cyclically following each other naturally for eons.

      • Yes. There are visible several indicators. One is the outline of Florida. Others are the extra peninsula and oversized channel islands off the coast of Southern California.

      • The map clearly uses present sea level, not glacial.

        During the LGM, the Grand Banks or Newfoundland and Georges Bank off New England were exposed and the Bahamas were mostly a single island.

        Across the Atlantic, the English Channel and North Sea were dry land, as was the Rockall Bank in the NE Atlantic, which is now a little rock islet.

        The Arctic and Pacific Oceans were separated by Beringia, a vast subcontinent connecting North America and Europe. In SE Asia, Indonesian islands were connected to the mainland.

    • WHOA!! Even that far back in time there was so much hot air in the DC area that even a glacier couldn’t cross the Potomac. Good to know I’ll be able to get by (as long as I can heat this place.

    • Yes, and that seawater was depleted in O18 which then evaporated and showed up as a doubly depleted band in the Greenland ice cores. The Younger Dryas was actually a warm period when rapid glacial melting produced a deluge of fresh water in the North Atlantic and a false low temperature indication in the ice cores.

      • Dang … now there’s an interesting theory. The d18O was from the fresh water and not from an actual temperature drop. Do you have any citations on that one?

        w.

      • Nice try pochas, but the younger dryas was established using palaeobotany, long before anyone measured isotopes.

      • @Willis, Smart Rock

        From
        http://www.geol.lu.se/personal/seb/Publ%202006-10/Global%20YD%20last%20edition.pdf

        “The idea that a sudden fresh-water event triggered the onset of Younger Dryas, such as the diversion of the outlet of Lake Agassiz from the Gulf of Mexico to an eastern outlet with a more or less catastrophic drainage through the St. Lawrence River (Broecker,et al., 1988) and a simultaneous Baltic Ice Lake drainage (Björck,et al., 1996) into the North Sea, is a mechanism that is supported by coupled atmosphere-ocean modeling (Manabe and Stouffer, 1988). A sudden decrease in salinity in areas where NADW normally occurs would have a rapid and disturbing effect on the THC. This would seriously hamper the northwards meridional heat advection, and this model ofexplaining the sudden onset and exceptional length of the Younger Dryas has been widely acknowledged as the most plausible mechanism for the onset of the oscillation”

        As stated above, the freshwater blanketing the North Atlantic would be depleted in O18 which would affect the O18 content of subsequent precipitation on Greenland. The sudden freshwater event could only come from a sudden warming. Attendant flooding of the Mississippi Valley and probably large areas of Europe would cause all sorts of confusing botanical stratigraphy.

    • Did anyone else happen to notice that the image shows very little sea ice in the Arctic during an Ice Age? That seems very interesting to me. I wonder if there is any basis to the drawing or if it’s pure conjecture.

      • on that theme it is interesting to note temperatures just below 80 degrees north have been cooler for much of the arctic summer than those above . much ice still lingering in hudson bay .

  12. I’m starting a new ocean current rapid response engineering team. I need grants and grant-supported loans to get it started and make it operational. Never mind if it works or not. Want to see my political connections and donor track record?

  13. If they’re taking requests can I have some nice weather (not too hot, not too cold) here in the East Midlands UK for the next 3 weeks? My family are coming over from Seattle and it would be nice to show them round without the bother of coats and umbrellas. Thanks.

  14. So now we have spatial two-point correlation as causation. It’s nice to add another dimension. Or is that one-point with a model on the other end?

  15. “…They found that it took more than 550 years for drought conditions to reach their full extent in the region, and about 450 years to return to pre-Younger Dryas levels after the North Atlantic Current began circulating again. The record suggests rainfall was about 25 percent lower than present levels during the cold snap…”

    So 50 years of cold weather is a “cold snap?” And a 25% drop in rainfall is “a drought?”

    A cold snap, by definition: “a sudden onset of a relatively brief period of cold weather.”
    A drought: “a long period of time during which there is very little or no rain.”

    These people have lost the ability to speak English. I strongly suspect that the thousand year dry “snap” disappears if you include some error bars.

  16. I love all the ‘coulds’ that the speculative scare mongering reports come up with.

    If my sheep started to hunt foxes I ‘could’ look forwards to lambing seasons when I no longer have to worry about foxes taking new-born lambs.

    The chances of that are Nil and as my grandmother used to say ‘if wishes were horses then tinkers would ride’.

    That for me about sums up ‘climate science’ – a basket-case of wishful thinking.

  17. I’m quite curious- what physical data show traces of changes in the circulation of ocean currents? Is it the content of sediments? What physical clues would such changes leave behind?

  18. Climate Science the place where hubris and incompetence meet. Can we stop calling it science now? The climate predictions should be right next to the horoscopes. Although horoscopes may be more accurate. Like if Jupter is up in Venus’s business then it’s going to get warmer or something or however the lingo goes.

  19. “They found that it took more than 550 years for drought conditions to reach their full extent in the region, and about 450 years to return to pre-Younger Dryas levels after the North Atlantic Current began circulating again.”

    If this is a cave that depends for its timelines on water dripping from the ceiling then it could have changed very quickly in the Philippines but it may have taken a long time for the aquifer to dry up, which it would do by slowly losing its flow volume. Then when it started raining again it would a long time for the aquifer to recharge and leak again into the cave at ‘full flow’. For this reason I am not sure this proxy has the sharpness of resolution that is available from an ice core.

    Is there any indication that this cave has such a sharp resolution and that it is capable of recording the temperature quickly? They state that the deposition of minerals was tracked, which is to say it is a flow-dependent proxy building up thin or thick layers per year or per decade. Have they assumed in their analysis that the flow is from a short, low capacity aquifer? It seems so. Maybe they didn’t think of it. The rainfall may have changed as abruptly as in Greenland and it would still give the pace they report.

    • Crispin, It the ‘leak’ might also have healed up during the dry period with salts in the shrinking water in the aquifer and it took, possibly a earthquake to refracture it. You know that most of these climate scientists are physicists and not geologists. They even have the temerity to wax strongly on botany. Recall the recent post on planting trees in Urban centres to cool off UHI. There they said the cooling by trees was caused by evapotranspiration, like sweat on human skin, without apparently being aware that part of the coolness in the shade is the endothermic photosynthesis and partly albedo from the canopy (~ 0.2, small but not insignificant).

  20. I thought that the causes of the Younger Dryas event were still hotly debated.
    As to the claim that there was a big surge of cold water from the NA continent, that too has been proposed, but never demonstrated using real world data. Nor is it proven that a surge of fresh water would stop the N. Atlantic conveyor, or that there would be a dramatic cooling if it did.

    • MarkW, read up more on YD. Was going to have an essay on YD in the book, but after months of evening/weekend research decided the science was (for me) sufficiently convincingly settled by many papers and counter papers to skip it. That science is pretty well settled.

    • Mark
      Yes its not the North Atlantic drift that keeps europe warm, that’s down to the Westerly air flow across the Atlantic. As shown by the winter of 1962/63 in europe, when blocking shut off the mild westerly winds.

  21. Funny how one small item can be used to deduce global weather patterns.

    By the way, no droughts so far in the West Coast have come even close to the Great Drought 500 years ago. Most of the native farming communities in Arizona perished and they left broken pottery all over the Tucson valley from Kitt Peak to Mount Lemmon.

  22. This research shows the issue l have with claims that ocean currents are the leaders in climate change.
    The claim been that the melting of the NA ice sheets were the cause of the cooling in the YD. Yet in order for the melting to cause the shut down of the North Atlantic drift then that would mean it must have been running during the ice age.So how could its shut down have caused cooling during YD and yet still there was a bitter cold climate in the NH for much longer during the ice age when the North Atlantic drift was up and running.

    • What is far less known is that there were two freshwater discharges at the end of the ice age. But only the first one caused a cooling event. The second one around 9500 years ago had little effect on the climate.
      Why should that be? my guess is because by this time the weather patterns had become far to variable for it to have a lasting impact. Because when there a increase in the variation of the weather from year to year. lt blocks the formation of major climate change from happening.

      • Exactly, and the opening of the Bering Strait was the cause? Principal fresh water input to the Arctic is the Strait?

  23. Hmmm…. they are sneaking in cooling! We will see more of this has bolder young scientists push back against near retirees of consensus climate. I laughed when they remarked that we had to do something to prevent the slowing of the Gulf Stream to prevent a 1000yrs drought in the Philipines, not thinking that other things might have slowed down the drip and maybe even sealed it off:

    https://wattsupwiththat.com/2015/09/02/ancient-cold-period-could-provide-clues-about-future-climate-change/#comment-2019906

    Where the drying up of aquifers could take hundreds of years to refill up again before the ‘drip’ in the caves could resume after the rains got started up and…

    https://wattsupwiththat.com/2015/09/02/ancient-cold-period-could-provide-clues-about-future-climate-change/#comment-2019976

    at the end of the drought the increasing salts in solution in the shrinking acquifers likely sealed off the ‘leaks’ to the cave delaying for a long time after the rains resumed the ‘drip’ on this single stalagmite.

  24. Do the authors of the paper mention Bond Events?

    The North Atlantic ice-rafting events happen to correlate with most weak events of the Asian monsoon for at least the past 9,000 years,[4][5] while also correlating with most aridification events in the Middle East for the past 55,000 years (both Heinrich and Bond events).[6][7] Also, there is widespread evidence that a ≈1,500 yr climate oscillation caused changes in vegetation communities across all of North America. https://en.wikipedia.org/wiki/Bond_event

    and

    … many if not most of the Dansgaard–Oeschger events of the last ice age, conform to a 1,500-year pattern, as do some climate events of later eras, like the Little Ice Age, the 8.2 kiloyear event, and the start of the Younger Dryas.

    There has been a lot of research on Bond Events; they seem like well accepted science. I haven’t seen the paper but it sounds like these guys are ignoring (or are ignorant of) them. Here’s a link to the paper: link

  25. I have never trusted using ice as a proxy for temperature… I just do not see how they can correct for certain events and conditions. Especially when they compare proxy readings using one approach (like O18) on Greenland ice versus proxies using another approach (like Deuterium) on Antarctic ice.

    For example, if the water vapor in an air mass moves over some mountains (or other obstruction that causes air to lift) it should produce rain that contains O18 at a slightly elevated ratio. If that same air mass then moves north and produces say snow…It is missing some of the O18 it was “expected” to have, and the temperature record proxy will be moved to a colder reading. (Am I right?) Also, they may interpret this in conjunction with other proxies to mean there is more fresh water, therefore more rainfall, therefore warmer weather.

    Opposite happens if the air mass take up water evaporated from water that is high in O18, the water vapor is now naturally rich on O18 and it will tend to have proxy readings showing warmer temperatures. So if the water vapor comes from fresh water or snow, it should have elevated O18.

    If you “assume” all the water vapor came from the ocean, and that the ratio does not change over time, then you can assume the proxy readings work reasonably well – but how do you know?

    By the time they add in all of their “adjustments”, they can make the proxies read just about anyway they want (kind of like the land temperature adjustments).

    At least with cave formations, you can reasonably tell that the formation was dryer or wetter over time – as long as the acidic conditions don’t change of course (if something were to remove some acidity from ground water, it will dissolve less limestone and therefore deposit less limestone, so it will look dryer at that period).

    So the finding that Greenland’s supposed temperature changes happened at a different speed then the supposed temperatures near the tropics doesn’t mean much – there are too many “assumptions” in proxy measurements.

  26. The magnitude of the ice sheets melting at that time were far greater than what is left in the Northern Hemisphere currently. The icecap over Sweden alone back then likely matched Greenland’s now.

    The oceans all over the entire planet were 400 feet lower. How much ice was that? Compare it with how much the the oceans would be expected to rise if Greenland melted in a hurry (which seems highly unlikely). As much as 30 feet?

    In terms of magnitude, this is a case of comparing apples with watermelons.

    • Caleb
      Did you know that they were two freshwater discharges at the end of the ice age.?
      Which begs the question “why did the second event have no impact on the climate” if these events are such a strong cause of climate change.

      • That is an excellent question, and is one I’m sure the better minds are grappling with. Better minds are humble, and know we are very ignorant concerning the most basic plumbing of deep-sea currents, and how they are engineered, and better minds also know that if their study is to benefit mankind they should begin by being able to forecast what leads to what. It is the more puny minds that march off to Paris with some flimsy concept, dreaming they can control what we can’t even forecast.

  27. I was under the impression that the YD came about because of a cosmic impact. How did that event turn off the conveyor?

  28. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”

    I am going to hazard a guess that NASA will use the GPM Core spacecraft in tandem with some other satellite yet to be named to begin to detect this horrifying Circulation Event unfolding in the oceans below, right before our very eyes.

  29. After reading the full paper and some its citations I conclude:

    1. Their results are in full agreement with the Arctic Iris Effect that I cross-posted here at WUWT yesterday http://landscapesandcycles.net/arctic-iris-effect-and-dansgaard-oeschger-event.html

    2. Suggestions that transition into and out of the Younger Dryas is based on previous assumptions that the AMOC turned off due to freshwater flooding. However they do not provide any new evidence to support that assertion. The turning on and off of the AMOC assumption has 2 problems. First that the AMOC is NOT driven by buoyancy the conveyor belt model assumes. The conveyor belt is rapidly being deconstructed. As Lozier 2010 wrote, ““the conveyor-belt model no longer serves the community well—not because it is a gross oversimplification but because it ignores crucial structure and mechanics of the ocean’s intricate global overturning.” Wunsch calls the conveyor a myth that has set back oceanography for decades.

    Second even if freshwater flooding could shut down the AMOC, there is no consensus if flooding ever happened and a growing number of papers presenting contradictory evidence as discussed at WUWT here https://wattsupwiththat.com/2011/10/05/evaporation-not-outflow-drained-ancient-lake-agassiz-during-the-younger-dryas/

    Finally the shutdown of the AMOC is based on proxies that measure Deep Water formation. A covering of ice will prevent water from contacting the freezing air temperatures and thus prevents formation of cold sinking water. However because Deep Water shuts off, the inflow of warm water does not! And water flowing into the Arctic simply exits at a different depth.

    The 2 models in their paper had very different sub-models with different sea ice extent and changes. The rapid change happened in the model with greater changes in sea ice, but not in the other model without the sea ice change, even though both models were being hosed with ad hoc fresh water.

    The Arctic Iris Effect readily explains the YD. Increased ice causes poor heat ventilation and rapid cooling, while reduced sea ice causes rapid warming. As in the rapid warming event of Dansgaard Oeschger events, Greenland and other ice caps experienced greater ice accumulation that was double the amount during the colder periods. That ice accumulation would readily cause rapid glacier expansion and calving that then traps sea ice preventing the ice from being flushed from Arctic and causing it to thicken.

    This paper’s only addition to our knowledge of the YD was demonstrating very little tropical temperature changes and reinforcing expectations of changes in precipitation. Changes in the ITCZ that coincide with changes in ice cover are well established, their observations merely added to that understanding. The lack of temperature changes in tropical waters simply supports the notion that minor changes in ocean temperature can be amplified by the iris effect

  30. “… what could happen if the planet’s ice sheets continue to lose mass and add freshwater to the North Atlantic.”

    Present day ice sheets melting into the North Atlantic? Who wrote this thing? There are only two ice sheets left, in Greenland and Antarctica. Jud Partin and his associates can’t possibly be suggesting that Antarctic melting adds freshwater to the North Atlantic.

  31. Freshwater Arctic ice melt is an effect, not a cause, of ocean driven climate change.

    (Confusion of cause and effect effect is a universal feature of the political narrative of self justification of totalitarian regimes, according to historian Anthony Beevor.)

    There is a fundamental difference between millenial scale ocean oscillations in the north and south hemispheres.
    In the NH changes between cold and warm periods are abrupt and more frequent.
    In the SH, changes are smooth, gradual and less frequent.
    This is explained by the chaotic nonlinear (Lyapunov) stability of the oceans in both hemispheres.
    The Atlantic Meridional Overturning Circulation (AMOC) contains a positive feedback between North Atlantic Deep Water (NADW) formation in the Norwegian Sea, and salinity arising from the Gulf Stream.
    And as we all know, a positive feedback within a dissipative oscillatory system will introduce chaotic fluctuation, sure as night follows day.
    This was well described in this paper by Weaver et al 2003:

    http://home.sandiego.edu/~sgray/MARS350/deglaciation.pdf

    This constitutes a positive feedback between the overturning circulation and the salinity in the North Atlantic first described by Stommel (33). Specifically, the intensified formation of NADW advects more saline subtropical waters to the northern North Atlantic, which increases surface density there and further intensifies the overturning circulation.

    This positive feedback between the Gulf stream, which carries saline water to the North Atlantic, and NADW, drives the chaotic fluctuation of the AMOC and (consequently) NH temperatures, which contrast with the slow smooth and serene ocean temperature oscillations in the SH. This contrast is what makes oceanography on our planet interesting – at least in our current continental configuration.

  32. Everything but the science is settled. Summary report: We don’t now what we think we know. Some of us knew that.

  33. There are piles and piles of Zombie theories associated with: the Younger Dryas, what causes cyclic abrupt climate change, what is the effect of changes in atmospheric CO2 on planetary climate, and related to what causes the glacial/interglacial cycle. Zombie theories fill the void when the true cause of what is observed is not known. The big barrier to solving the climate puzzle is the sun is significantly different than the standard model. There are piles and piles of astronomical anomalies and paradoxes that support that assertion.

    Back to the Zombie theories.

    As noted in the next linked paper, the melt pulse occurred a 1000 years prior to the Younger Dryas event which has been known for at least a decade. No cooling at that time. There is not even correlation in time with the melt pulse and the abrupt onset of cooling in North America and Europe. There is no discrete conveyor to interrupt. Regardless modeling indicates a complete interruption to the North Atlantic drift current would only cool Europe and North America a couple of degrees.

    https://www.rug.nl/research/portal/files/6661387/2000QuatIntRenssen.pdf

    Reduced solar activity as a trigger for the start of the Younger Dryas?
    …We discuss the possibility that an abrupt reduction in solar irradiance (William: sun causes what is observed when the solar cycle restarts) triggered the start of the Younger Dryas and we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an & 2500 year quasi-cycle * also found in the 14C record* that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere.

    It is interesting that the YD 1200 year cooling occurred when summer insolation at 65N was maximum. The theory that summer solar insolation at 65N controls the glacial/interglacial cycle is also a Zombie theory.

    There is the largest C14 change in the Holocene during the Younger Dryas. The cause of the largest C14 change in the Holocence is the cause of the YD. The cause of cyclic abrupt climate change is the sun which causes abrupt changes to the geomagnetic field. During a geomagnetic excursion multiple poles appear on the earth, include a low latitude geomagnetic pole which cause a more than doubling of GCR in the vicinity of the pole which explains the low latitude cooling. There is a delay in the change in low latitude magnetic pole occurrence due to the back emf that is generated to resist the change in the liquid core. The first change in the field occurs at the site of massive change in the field which is where the burn marks are. The burn marks are caused by a massive movement of electrical charge from the ionosphere to the surface of the planet. That creates the high temperature debris with no impact and no iridium.

    P.S. The paleo data supports the assertion that Interglacial periods end abruptly not gradually. There is a new computer model run that has published in Nature by the cult of CAGW to push the Zombie theory that interglacial periods end gradually.

    This is the Greenland Ice sheet temperature data for the last 100,000 years. Can you see the cyclic abrupt changes?

    ClimateMyth/Zombie Theory 1- An interruption to the discrete Gulf Stream (a discrete deep water return for the North Atlantic Drift Current (aka The ‘Gulf Stream’) does not exist, see below, but even if it did so a melt pulse could interrupt it) would not result in significant cooling of Europe or America. The Gulf stream myth has been perpetuated for almost 20 years.

    http://www.atmos.washington.edu/~david/Gulf.pdf

    Is the Gulf Stream responsible for Europe’s mild winters?
    By R. SEAGER1¤, D. S. BATTISTI2, J. YIN2, N. GORDON1, N. NAIK1, A. C. CLEMENT3 and M. A. CANE1

    Is the transport of heat northward by the Gulf Stream and North Atlantic Drift, and its subsequent release into the midlatitude westerlies, the reason why Europe’s winters are so much milder than those of eastern North America and other places at the same latitude? Here, it is shown that the principal cause of this temperature difference is advection by the mean winds. South-westerlies bring warm maritime air into Europe and north westerlies bring frigid continental air into north-eastern North America. Further, analysis of the ocean surface heat budget shows that the majority of the heat released during winter from the ocean to the atmosphere is accounted for by the seasonal release of heat previously absorbed and not by ocean heat-convergence. Therefore, the existence of the winter temperature contrast between western Europe and eastern North America does not require a dynamical ocean.

    Two experiments with an atmospheric general-circulation model coupled to an ocean mixed layer confirm this conclusion. The difference in winter temperatures across the North Atlantic, and the difference between western Europe and western North America, is essentially the same in these models whether or not the movement of heat by the ocean is accounted for. In an additional experiment with no mountains, the flow across the ocean is more zonal, western Europe is cooled, the trough east of the Rockies is weakened and the cold of north-eastern North America is ameliorated. In all experiments the west coast of Europe is warmer than the west coast of North America at the same latitude whether or not ocean heat transport is accounted for. In summary the deviations from zonal symmetry of winter temperatures in the northern hemisphere are fundamentally caused by the atmospheric circulation interacting with the oceanic mixed layer.

    http://www.americanscientist.org/issues/feature/2006/4/the-source-of-europes-mild-climate

    The Source of Europe’s Mild Climate
    The notion that the Gulf Stream is responsible for keeping Europe anomalously warm turns out to be a myth

    All Battisti and I did was put these pieces of evidence together and add in a few more illustrative numerical experiments shutdown of the North Atlantic thermohaline circulation. Their modeled climate cooled by a few degrees on both sides of the Atlantic and left the much larger difference in temperature across the ocean unchanged. Other published model experiments went on to show the same thing. Further, the distinction between maritime and continental climates had been a standard of climatology for decades, even centuries.

    Why hadn’t anyone done that before? Why had these collective studies not already led to the demise of claims in the media and scientific papers alike that the Gulf Stream keeps Europe’s climate just this side of glaciation?

    It seems this particular myth has grown to such a massive size that it exerts a great deal of pull on the minds of otherwise discerning people.

    This is not just an academic issue. The play that the doomsday scenario has gotten in the media—even from seemingly reputable outlets such as the British Broadcasting Corporation—could be dismissed as attention-grabbing sensationalism. But at root, it is the ignorance of how regional climates are determined that allows this misinformation to gain such traction. Maury should not be faulted; he could hardly have known better. The blame lies with modern-day climate scientists who either continue to promulgate the Gulf Stream-climate myth or who decline to clarify the relative roles of atmosphere and ocean in determining European climate.

    This abdication of responsibility leaves decades of folk wisdom unchallenged, still dominating the front pages, airwaves and Internet, ensuring that a well-worn piece of climatological nonsense will be passed down to yet another generation.

    The comet/asteroid impact theory is a zombie theory. As noted by an astrophysicist who commented on a NOVA program. He noted also that no one asked the astrophysics community for their input on the YD impact theory. It is physically impossible for a single comet/asteroid to cause ten burn marks with observed pattern. It would take eight to nine separate comets and/or asteroids which is ridiculous as the burn marks occurred almost simultaneously.

    There are ten burn mark sites (nine in the North America and one in Europe).

    http://www.pnas.org/content/suppl/2007/09/20/0706977104.DC1
    It is not possible for a single object to ‘break up’ to cause the burn marks. Look at the locations where the burn marks were found.

    Fig. 9. Research sites with calibrated YDB ages, including Lommel, Belgium, shown in Inset. High-Ir sites are shown in green. For the Bays, three of five sediment analyses revealed detectable Ir values, although radiocarbon ages of the Bays are inconsistent. Sediments from sites with no detectable Ir values (<0.5 ppb) are shown in brown. Sites with black mats are marked with inverted triangles. The approximate extent of the North American ice sheets at 12.9 ka is shown in blue-green, which is consistent with our observations that all sites were ice-free at the time of the YD event.

    • Greenland temperatures from the ice cores during the last ice age above.

      First issue is that the temperature change is miscalibrated by the use of faulty borehole models. The temperature change was not 20C but more like 8C to 10C. The correct formulae for the oxygen isotopes are only 8C of temperature change, 3C in the Younger Dryas.

      Second, the Younger Dryas is a very small part of the downspike in temperatures during the period. Temperatures started crashing at 14,300 years ago, well before the Younger Dryas period which started at 12,800 years ago. Why are they so fixated on the Younger, when the change in the climate started about 3,000 years earlier when there was rapid warming followed by rapid cooling and then there was another period of cooling called the Younger Dryas.

      Third, the entire ice core record shows extreme variability. There were more 30 Younger Dryas-type events in the 100,000 years of the ice age. Why is the Younger Dryas so special. What about the Older Dryas. Why is there no papers about it. If one is going to try to explain the Younger Dryas, maybe one should start with explaining the 30 similar events which happened during the whole ice age.

      Climate science is focused on cash and splash; not true understanding.

  34. Really nothing much new in this paper. Problem is that Greenland is and always has been a “regional” teleconnection point. Opposite phase downstream(and upstream).

  35. “As the world warmed after the last ice age, glaciers melted and diluted northern seawater with freshwater. The resulting change in ocean water density disrupted the current and, in effect, the climate, causing a period of global cooling.”

    I assume that the glaciers melt at the end of every “ice age”

    Is there evidence for a Younger Dryas type event at the end of each glacial period???

  36. Seems to me, I recall something of a theory that the YD was due to a “sudden” release of fresh water.

    I don’t see that happening to day. The ice is already melted considerably in the NH.

  37. I still await an EXPLANATION – not a description – of what CAUSED the warming that ended the ice ages.
    Was it elevated levels of CO2??
    If so, from where did this CO2 come?

    • It was the same cause as the ends of the previous ice ages. CO2 had nothing to do with it. A warmer world meant more CO2 in the air. The raised concentration was a result of warming, not the cause.

      Milankovitch Cycles, ie orbital and rotational mechanics, cause the cyclic ice ages, ie NH glaciations. The key factor is insolation at 75 degrees N.

  38. This is my thought about the bigger picture of why the climate changes. D/O events and the Arctic Iris theory which I sent in an earlier post simply being superimposed on this bigger picture and adding to the climate instability y during glacial times all though this Arctic Iris Effect is always in operation but not as dramatic during inter- glacial periods of time.

    Below are my thoughts about how the climatic system may work. It starts with interesting observations made by Don Easterbrook. I then reply and ask some intriguing questions at the end which I hope might generate some feedback responses. I then conclude with my own thoughts to the questions I pose.

    From Don Easterbrook – Aside from the statistical analyses, there are very serious problems with the Milankovitch theory. For example, (1) as John Mercer pointed out decades ago, the synchronicity of glaciations in both hemispheres is ‘’a fly in the Malankovitch soup,’ (2) glaciations typically end very abruptly, not slowly, (3) the Dansgaard-Oeschger events are so abrupt that they could not possibility be caused by Milankovitch changes (this is why the YD is so significant), and (4) since the magnitude of the Younger Dryas changes were from full non-glacial to full glacial temperatures for 1000+ years and back to full non-glacial temperatures (20+ degrees in a century), it is clear that something other than Milankovitch cycles can cause full Pleistocene glaciations. Until we more clearly understand abrupt climate changes that are simultaneous in both hemispheres we will not understand the cause of glaciations and climate changes.

    My explanation:

    I agree that the data does give rise to the questions/thoughts Don Easterbrook, presents in the above. That data in turn leads me to believe along with the questions I pose at the end of this article, that a climatic variable force which changes often which is superimposed upon the climate trend has to be at play in the changing climatic scheme of things. The most likely candidate for that climatic variable force that comes to mind is solar variability (because I can think of no other force that can change or reverse in a different trend often enough, and quick enough to account for the historical climatic record, and can perhaps result in primary and secondary climatic effects due to this solar variability, which I feel are a significant player in glacial/inter-glacial cycles, counter climatic trends when taken into consideration with these factors which are , land/ocean arrangements , mean land elevation ,mean magnetic field strength of the earth(magnetic excursions), the mean state of the climate (average global temperature gradient equator to pole), the initial state of the earth’s climate(how close to interglacial-glacial threshold condition it is the ice dynamic/ average global temperature) the state of random terrestrial(violent volcanic eruption, or a random atmospheric circulation/oceanic pattern that feeds upon itself possibly) /extra terrestrial events (super-nova in vicinity of earth or a random impact) along with Milankovitch Cycles, and maybe a roll for Lunar Effects.

    What I think happens is land /ocean arrangements, mean land elevation, mean magnetic field strength of the earth, the mean state of the climate, the initial state of the climate, and Milankovitch Cycles, keep the climate of the earth moving in a general trend toward either cooling or warming on a very loose cyclic or semi cyclic beat(1470 years or so) but get consistently interrupted by solar variability and the associated primary and secondary effects associated with this solar variability, and on occasion from random terrestrial/extra terrestrial events, which brings about at times counter trends in the climate of the earth within the overall trend. While at other times when the factors I have mentioned setting the gradual background for the climate trend for either cooling or warming, those being land/ocean arrangements, mean land elevation, mean state of the climate, initial state of the climate, Milankovitch Cycles , then drive the climate of the earth gradually into a cooler/warmer trend(unless interrupted by a random terrestrial or extra terrestrial event in which case it would drive the climate to a different state much more rapidly even if the climate initially was far from the glacial /inter-glacial threshold, or whatever general trend it may have been in ) UNTIL it is near that inter- glacial/glacial threshold or climate intersection at which time allows any solar variability and the associated secondary effects, and or other forcing no matter how SLIGHT at that point to be enough to not only promote a counter trend to the climate, but cascade the climate into an abrupt climatic change. The back ground for the abrupt climatic change being in the making all along until the threshold glacial/inter-glacial intersection for the climate is reached ,which then gives rise to the abrupt climatic changes that occur and possibly feed upon themselves while the climate is around that glacial/inter-glacial threshold resulting in dramatic semi cyclic constant swings in the climate from glacial to inter-glacial while factors allow such an occurrence to take place. Which was the case 20000 years ago to 10000 years ago.

    The climatic back ground factors (those factors being previously mentioned) driving the climate gradually toward or away from the climate intersection or threshold of glacial versus interglacial. However when the climate is at the intersection the climate gets wild and abrupt, while once away from that intersection the climate is more stable.

    Although random terrestrial events and extra terrestrial events could be involved some times to account for some of the dramatic swings in the climatic history of the earth( perhaps to the tune of 10% ) at any time , while solar variability and the associated secondary effects are superimposed upon the otherwise gradual climatic trend, resulting in counter climatic trends, no matter where the initial state of the climate is although the further from the glacial/inter-glacial threshold the climate is the less dramatic the overall climatic change should be, all other items being equal.

    The climate is chaotic, random, and non linear, but in addition it is never in the same mean state or initial state which gives rise to given forcing to the climatic system always resulting in a different climatic out-come although the semi cyclic nature of the climate can still be derived to a degree amongst all the noise and counter trends within the main trend.

    QUESTIONS: The Arctic Iris Effect goes to some degree in answering some of these questions combined with my other thoughts for the bigger picture in my opinion.

    Why is it when ever the climate changes the climate does not stray indefinitely from it’s mean in either a positive or negative direction? Why or rather what ALWAYS brings the climate back toward it’s mean value ? Why does the climate never go in the same direction once it heads in that direction?

    Along those lines ,why is it that when the ice sheets expand the higher albedo /lower temperature more ice expansion positive feedback cycle does not keep going on once it is set into motion? What causes it not only to stop but reverse?

    Vice Versa why is it when the Paleocene – Eocene Thermal Maximum once set into motion, that being an increase in CO2/higher temperature positive feedback cycle did not feed upon itself? Again it did not only stop but reversed?

    My conclusion is the climate system is always in a general gradual trend toward a warmer or cooler climate in a semi cyclic fashion which at times brings the climate system toward thresholds which make it subject to dramatic change with the slightest change of force superimposed upon the general trend and applied to it. While at other times the climate is subject to randomness being brought about from terrestrial /extra terrestrial events which can set up a rapid counter trend within the general slow moving climatic trend.

    .

    Despite this ,if enough time goes by (much time) the same factors that drive the climate toward a general gradual warming trend or cooling trend will prevail bringing the climate away from glacial/inter-glacial threshold conditions it had once brought the climate toward ending abrupt climatic change periods eventually, or reversing over time dramatic climate changes from randomness, because the climate is always under a semi extra terrestrial cyclic beat which stops the climate from going in one direction for eternity.

  39. Savlatore,

    “From Don Easterbrook – Aside from the statistical analyses, there are very serious problems with the Milankovitch theory. For example, (1) as John Mercer pointed out decades ago, the synchronicity of glaciations in both hemispheres is ‘’a fly in the Malankovitch soup,’ (2) glaciations typically end very abruptly, not slowly, (3) the Dansgaard-Oeschger events are so abrupt that they could not possibility be caused by Milankovitch changes (this is why the YD is so significant), and (4) since the magnitude of the Younger Dryas changes were from full non-glacial to full glacial temperatures for 1000+ years and back to full non-glacial temperatures (20+ degrees in a century), it is clear that something other than Milankovitch cycles can cause full Pleistocene glaciations. Until we more clearly understand abrupt climate changes that are simultaneous in both hemispheres we will not understand the cause of glaciations and climate changes.”

    I see no problems.

    1) Why is synchronicity a problem? The orbital mechanics affect both hemispheres. Perhaps you’re concerned about rotational mechanical effects, such as axial tilt. Both hemispheres are affect equally by insolation, but just at different times of the year. What controls the Pleistocene glaciations however is indeed the Northern Hemisphere, since the SH has been covered by ice sheets of varying extent since the Oligocene.

    2) Glaciations most certainly do not end abruptly. From the depths of the LGM to the onset of the Holocene took about 9000 years (20 Ka to 11 Ka), and to continued deglaciation down to today’s levels thousands of years more. Even the period of most rapid deglaciation took thousands of years, with interrupted by cold snaps like the Dryases.

    3) Why do D/O events have to be controlled by orbital mechanics? They occur throughout glacial epochs, not just during deglaciations. Celestial mechanics might contribute to them, but they well could have other causes.

    4) Sorry, but “since the magnitude of the Younger Dryas changes were from full non-glacial to full glacial temperatures for 1000+ years and back to full non-glacial temperatures (20+ degrees in a century), it is clear that something other than Milankovitch cycles can cause full Pleistocene glaciations” makes no sense. The YD was during a deglaciation, not during a glaciation, ie ice sheet build up. Whatever caused the Dryas and other rapid cooling episodes is associated with deglaciation, not glaciation. That should be obvious.

  40. They keep avoiding all the evidence. Before the last advance of ice, there were mammoths feeding on flowers in the northern latitudes. The mammoths and all other animals and trees were shredded apart by extremely high winds and some were frozen solid with their last, undigested meal in their stomach. The ice spread rapidly and the North Atlantic circulation shut down as a result, not as a cause.

    The mechanism that drove this sudden change was an anomalous buildup of heat in the Atlantic ocean, which drove the Gulf Stream clear up to the Labrador and Norwegian seas. The heated waters at such high latitudes created an intense polar vortex, with two major super hurricanes operating simultaneously. At the high latitude, where the atmosphere is considerably shallower, the heat columns from the hurricanes punctured the upper atmosphere and pumped large quantities of heat in the form of infrared radiation into space. The leftover moist air was super cooled and fell to the Earth as ice. The momentum of the storms were so great, they created a mountain of ice over ten miles high that dented the Earth’s crust causing volcanic ruptures in Massachusetts, Connecticut, and Pennsylvania while also sending enormous rivers of ice flowing across the North American continent and all the way down to Illinois.

    Enough of this crap about North Atlantic ocean currents causing the Ice Age, the sudden halt of circulation was the result of the Ice Age.

  41. “At a conference in Paris during July of more than 2,000 climate scientists, the potential collapse of the North Atlantic Current’s circulation was identified as a possible catastrophic consequence of climate change.”

    Well they have misunderstood the fundamental dynamics then. Increased forcing of the climate (positive NAO/AO) increases AMOC rates, and certainly will not promote the any growth of ice shelves that could disrupt ocean overturning at the Achilles Heel of the North Atlantic below Greenland.

  42. I think if one subscribes to the Arctic Iris Effect theory(as I do) this takes away from the importance of the role the AMOC/NAO-AO relationship may play in the resultant Arctic temperature trends.

    Time will tell but if this theory is correct and the heat ventilation from the Arctic Ocean subsides partly due to the solar insolation trends going forward then the Arctic is going to cool despite the AMOC /NAO relationship.

    The Arctic Iris Effect theory explains abrupt climate change and the random nature of D/O events and why the magnitude of these D/O is greater during glacial times versus non glacial times while nevertheless still being present in the non glacial times at a much reduced magnitude.

    I was never sold on the 1470 year semi quasi climate cycle per say and the last 20,000 years of the historical climatic record supports this in my opinion ,although I do believe in a semi loose climate cycle due to Land/Ocean Arrangements, Initial State Of The Climate -Ice Dynamic, Milankovitch Cycles, Geo Magnetic Field Strength, with Solar Variability superimposed upon these climatic items..

  43. That is not to say the AMOC /NAO relationship may not play any role at all. One has to be careful in the elimination or total embrace of any one theory, especially those that has the single cause and effect which is what climate scientist consistently try to do. It is very likely a combination of factors and maybe for example the resultant Arctic temperature trends going forward is a greater combination of factors then even just the Arctic Iris Effect , or the AMOC/NAO relationship theories combined ,let alone these two theories not inclusive of one another although I think the Arctic Iris Effect has the most merit and probably the greatest overall impact on the Arctic temperatures for my money.

    One fact that I am certain of is, it is not the warming surface air temperatures which has caused the thinning of the sea ice , but rather the other way around as this Arctic Iris theory suggest.

    .

    • warrenlb flubbed the link; replace the 2nd letter of the host’s url with an ‘o’ and you’ll go where warrenlb wants you to go, but I’m not going to do his work for him.

      • What does that have to do with anything relevant?

        Please do as repeatedly asked and explain how AGW can possibly exist when rising CO2 coincided with global cooling from 1945 to 1977 and again from 2005 until now, which cooling was preceded by flat temperatures from 1997 to 2004.

        Thanks!

    • A totally discredited load of bull ordure which has been left to rot since 2015/02/24, of course.

      Your advocacy of such a sad, worthless unscientific effort clearly shows you really haven’t a clue.

      What a sad, bitter little specimen you are.

  44. Another thought .. relative to ending ice ages…
    When we approach ‘snowball earth,’ some of the ocean’s water is on continents as ice. The normally used estimate is that during the last ice age, ocean levels were more than 100 meters lower than at present. It has been theorized that methane formed from decaying biological material deposited in the oceans as clathrates, which decomposed rather quickly when the hydro static head declined sufficiently.

    Sound plausible. Methane is a wonderful greenhouse gas.

  45. “A slowdown of the ocean circulation is a double-edged sword: If we see some temperature changes associated it … and somehow are quick to act and alleviate the change, then we have the potential to stop it before it impacts rainfall globally,” Partin said. “The longer the circulation event lasts means that it will take that much longer for rainfall to recover.”

    This is the funniest part as we have absolutely no chance of preventing something like this from happening ever. First you have to make km’s of ice, place them over Canada and parts of USA and then melt trillions of gallons of water into the North Atlantic ocean. It is therefore impossible to prevent a scenario that occurred with conditions that the planet no longer has. The change was huge around North Atlantic Ocean, Iceland and Western Europe. The UK would have ice flows going up against it’s western coast even in Summer. Polar arctic waters were to the western side, with temperatures that resemble what are seen around Southern Greenland’s coast now.

    • Here’s some actual science being practiced by paleoclimatologists, a rarity these days (the YD has been called HE 0):

      http://www.nature.com/ngeo/journal/v7/n2/full/ngeo2045.html

      Nature Geoscience | Article

      Muted change in Atlantic overturning circulation over some glacial-aged Heinrich events

      Jean Lynch-Stieglitz, Matthew W. Schmidt, L. Gene Henry, William B. Curry, Luke C. Skinner, Stefan Mulitza, Rong Zhang & Ping Chang

      Heinrich events—surges of icebergs into the North Atlantic Ocean—punctuated the last glacial period. The events are associated with millennial-scale cooling in the Northern Hemisphere. Fresh water from the melting icebergs is thought to have interrupted the Atlantic meridional overturning circulation, thus minimizing heat transport into the northern North Atlantic. The northward flow of warm water passes through the Florida Straits and is reflected in the distribution of seawater properties in this region. Here we investigate the northward flow through this region over the past 40,000 years using oxygen isotope measurements of benthic foraminifera from two cores on either side of the Florida Straits. These measurements allow us to estimate water density, which is related to flow through the thermal wind balance. We infer a substantial reduction of flow during Heinrich Event 1 and the Younger Dryas cooling, but little change during Heinrich Events 2 and 3, which occurred during an especially cold phase of the last glacial period. We speculate that because glacial circulation was already weakened before the onset of Heinrich Events 2 and 3, freshwater forcing had little additional effect. However, low-latitude climate perturbations were observed during all events. We therefore suggest that these perturbations may not have been directly caused by changes in heat transport associated with Atlantic overturning circulation as commonly assumed.

      • “However, low-latitude climate perturbations were observed during all events. We therefore suggest that these perturbations may not have been directly caused by changes in heat transport associated with Atlantic overturning circulation as commonly assumed.”

        That’s because there has been no evidence that the Gulf stream paused or stopped during changes in heat transport associated with AMOC. Warm waters were transported further South and East instead of North via the Gulf Stream. A polar ocean gyre that developed prevented this from happening. Therefore climate was able to function near normal in low latitudes only being slightly cooler. (still 1-2 c below normal)

  46. my memory is trying to remind me something of a power generation scheme the euros were promoting years ago. Seems like they were trying to use ocean currents as a massive power source for electric power. oops

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