Guest essay by Eric Worrall
The alleged weakening of the Atlantic Meridional Overturning Circulation appears to be triggering a growing amount of speculation about abrupt cooling, like the plot of the movie “The Day After Tomorrow”.
Crippled Atlantic currents triggered ice age climate change
The last ice age wasn’t one long big chill. Dozens of times temperatures abruptly rose or fell, causing all manner of ecological change. Mysteriously, ice cores from Greenland and Antarctica show that these sudden shifts—which occurred every 1500 years or so—were out of sync in the two hemispheres: When it got cold in the north, it grew warm in the south, and vice versa. Now, scientists have implicated the culprit behind those seesaws—changes to a conveyor belt of ocean currents known as the Atlantic Meridional Overturning Circulation (AMOC).
These currents, which today drive the Gulf Stream, bring warm surface waters north and send cold, deeper waters south. But they weakened suddenly and drastically, nearly to the point of stopping, just before several periods of abrupt climate change, researchers report today in Science. In a matter of decades, temperatures plummeted in the north, as the currents brought less warmth in that direction. Meanwhile, the backlog of warm, southern waters allowed the Southern Hemisphere to heat up.
AMOC slowdowns have long been suspected as the cause of the climate swings during the last ice age, which lasted from 110,000 to 15,000 years ago, but never definitively shown. The new study “is the best demonstration that this indeed happened,” says Jerry McManus, a paleo-oceanographer at Columbia University’s Lamont-Doherty Earth Observatory, and a study author. “It is very convincing evidence,” adds Andreas Schmittner, a climate scientist at Oregon State University, Corvallis. “We did not know that the circulation changed during these shorter intervals.”
…
Another question is whether the AMOC—currently known to be in decline—could drop off suddenly today, as depicted in the 2004 movie The Day After Tomorrow, causing temperatures to plummet across northwestern Europe. Schmittner says the past provides an eye-opener. “It’s evidence that this really did happen in the past, on short time scales.” But McManus says that studies looking deeper into the ice ages have found that the 1500-year climate oscillations tend not to be nearly as strong during interglacial periods. “It would suggest that this kind of thing isn’t so likely to happen today,” he says. On the other hand, he adds, “In most interglacials, Greenland didn’t melt … and Greenland is currently melting.”
Read more: http://www.sciencemag.org/news/2016/06/crippled-atlantic-conveyor-triggered-ice-age-climate-change
The abstract of the study;
North Atlantic ocean circulation and abrupt climate change during the last glaciation
The last ice age was characterized by rapid and hemispherically asynchronous climate oscillations, whose origin remains unresolved. Variations in oceanic meridional heat transport may contribute to these repeated climate changes, which were most pronounced during marine isotope stage 3 (MIS3), the glacial interval twenty-five to sixty thousand years ago. We examined climate and ocean circulation proxies throughout this interval at high resolution in a deep North Atlantic sediment core, combining the kinematic tracer Pa/Th with the deep water-mass tracer, δ13CBF. These indicators suggest reduced Atlantic overturning circulation during every cool northern stadial, with the greatest reductions during episodic Hudson Strait iceberg discharges, while sharp northern warming followed reinvigorated overturning. These results provide direct evidence for the ocean’s persistent, central role in abrupt glacial climate change.
Read more: http://science.sciencemag.org/content/early/2016/06/29/science.aaf5529
Is the Atlantic Meridional Overturning Circulation slowing? Models suggest it should be – but observation based studies have not found evidence of a slowdown.
Who else is speculating about abrupt cooling? One name which might surprise you is former NASA GISS director James Hansen. From Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming could be dangerous p3774;
… Global temperature becomes an unreliable diagnostic of planetary condition as the ice melt rate increases. Global energy imbalance (Fig. 15b) is a more meaningful measure of planetary status as well as an estimate of the climate forcing change required to stabilize climate. Our calculated present energy imbalance of ∼ 0.8 W m−2 (Fig. 15b) is larger than the observed 0.58 ± 0.15 W m−2 during 2005–2010 (Hansen et al., 2011). The discrepancy is likely accounted for by excessive ocean heat uptake at low latitudes in our model, a problem related to the model’s slow surface response time (Fig. 4) that may be caused by excessive small-scale ocean mixing.
Large scale regional cooling occurs in the North Atlantic and Southern oceans by mid-century (Fig. 16) for 10-year doubling of freshwater injection. A 20-year doubling places similar cooling near the end of this century, 40 years ear- lier than in our prior simulations (Fig. 7), as the factor of 4 increase in current freshwater from Antarctica is a 40-year advance.
Cumulative North Atlantic freshwater forcing in sverdrup years (Sv years) is 0.2 Sv years in 2014, 2.4 Sv years in 2050, and 3.4Sv years (its maximum) prior to 2060 (Fig. S14). The critical issue is whether human-spurred ice sheet mass loss can be approximated as an exponential process during the next few decades. Such nonlinear behavior depends upon amplifying feedbacks, which, indeed, our climate simulations reveal in the Southern Ocean. …
Read more: http://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016.pdf
Naturally most of the climate scientists who make such predictions expect the cooling to occur over a relatively short timescale, before the ice melt forcing which causes the predicted cooling is overwhelmed by our continued sinful emissions of CO2. But a fallback prediction of imminent abrupt cooling does conveniently make it rather difficult to falsify anthropogenic climate theories based on temperature alone, should global temperatures suddenly drop.
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temperatures shall drop. Poulos has proven it in a recent paper.
.
http://opagos.tumblr.com/post/146358209620/documentation-of-the-solar-activity-variations-and
I guess “proof” is in the eye of the reader.
Poulos has answered to the critique that tidal forces from orbiting planets are very weak to produce any visible effect to sun
http://opagos.tumblr.com/post/146837451515/dimitris-pouloss-answer-to-the-critique-that
The Sun’s rotation period varies with latitude on the Sun. Equatorial regions rotate faster than polar regions. The equatorial regions rotate in about 25 days. The regions at 60 degrees latitude rotate in about 31 days. Polar regions rotate in about 36 days.
The cooling has to come accompanied of a slowdown of AMOC, and be of regional nature, otherwise it is of not use to Hansen’s hypothesis. Very difficult conditions to meet indeed. A global cooling wouldn’t cut it.
In the real world where the data is even modestly scrutinised, not the kind of imaginary mal-constructed number series, as the so called global temperature is, the CET data is among the best or perhaps the best long term data set we have.
The most recent data shows that the short term average temperature has followed the fall in the solar activity with about five years delay. It may be of some concern that this is the sharpest fall since 1870.
http://www.vukcevic.talktalk.net/CET2015.gif
here I used 11 year (solar cycle length) low pass filter, but a very similar result is obtained by 11 year moving average, the LPF processing is preferable since the moving averages introduce some minor artefacts.
Vukcevic – thanks
I did not know what CET temp meant. I found this:
“The Central England Temperature (CET) record is a meteorological dataset originally published by Professor Gordon Manley in 1953 and subsequently extended and updated in 1974, following many decades of painstaking work. The monthly mean surface air temperatures, for the Midlands region of England, are given (in degrees Celsius) from the year 1659 to the present.
This record represents the longest series of monthly temperature observations in existence. It is a valuable dataset for meteorologists and climate scientists. It is monthly from 1659, and a daily version has been produced from 1772. The monthly means from November 1722 onwards are given to a precision of 0.1 °C. The earliest years of the series, from 1659 to October 1722 inclusive, for the most part only have monthly means given to the nearest degree or half a degree, though there is a small ‘window’ of 0.1 degree precision from 1699 to 1706 inclusive. This reflects the number, accuracy, reliability and geographical spread of the temperature records that were available for the years in question.”
I can see that its value is in the length of time within the record. What is you view on the “precision of 0.1 C” from 1722 onward” How is this possible in the 18th and 19th century?
A question for statisticians: If enough stations, over enough time, are measured to precision 0.5-1 C, can the mean be calculated to 0.1 C? Stupid question?
Mr. Carter, thanks for your comment
The Central England Temperature (CET) records cover the triangle London-Bristol-Liverpool. Yes, I would agree that 0.1C accuracy for the early records as the result of averaging from number of meteorological stations may appear problematic. However from the climate change point of view, when data are further averaged over period of years as in the graph above these errors make very little difference.
I did a following test: all monthly temperatures before 1900 rounded to the nearest degree C, than calculated annual average (using monthly weighted values), than calculated 11 year average to one decimal point, the result for all practical purposes was identical to using the officially quoted values, to calculate the same average.
The UK met office changed their method of the CET annual calculations to using monthly weighted values in January 2015 after my personal urging them to do so, outlining the advantages of the method.
The CET data are available from here: http://www.metoffice.gov.uk/hadobs/hadcet/cetml1659on.dat
typo: then
Vukcevic – thanks
Before one can ask if there is global warming or global cooling one must first establish what is the norm!!! How can we determine climate change if we don’t have a established reference point?
No melting, fewer minerals for the oceans. No El Nino and no occasional Big Dusts from inland Australia mean fewer minerals for the ocean. Phytoplankton need their vitamins. All meant to happen. What goes around etc…
Just enjoy this warm moment in the Holocene before we get clobbered by a Bond Event or Laki-scale eruption. (We can put our climate experts to work wiping down solar panels, more as punishment than help.)
So true. There are many more natural disasters with higher catastrophic effects than pumping CO2 into the atmosphere. A large San Andreas Fault earthquake in the L.A. basin, or Laki-style eruption, or landslide from La Palma in the Canary Islands, have the potential to collapse entire economies of nations around the world. These are the “known unknowns” that should be researched for survival’s sake, much more than trace atmospheric gases.
The Storegga Slides, with tsunamis, occurred a mere 8000 years ago. And Northern Europeans now worry about a bit of chill coming off things?
“In most interglacials, Greenland didn’t melt … and Greenland is currently melting.”
How could they possibly know what went on in “most” interglacials? We have a good chunk of Eemian ice left over from the last one, which was for 4000 years warmer than this one, but as far as I know there ain’t nuthin’ left up there of the prior interglacials.
The reason for NH instability and oscillation contrasting with SH stability and smoother, slower transitions is well established oceanography. The NH has more land and more complex ocean shapes and this leads among other things to the AMOC. The AMOC contains a positive feedback involving salinity, and in the context of the dissipative quasi-chaotic ocean system this positive feedback leads inevitably to spontaneous nonlinear oscillation.
The salinity positive feedback works as follows: the gulf stream brings warm and high salinity water to the north east Atlantic from the Carribean. In the Norwegian sea thus water is rapidly cooled, where its higher salinity gives it exceptionally high density causing it to sink to the ocean floor, forming the cold bottom water downwelling that drives the THC. This bottom cold water flows south, which impells the contrary surface flow of warm water northward, that is, reinforcing the gulf stream.
This positive feedback leads to rapid excursions of strong gulf stream which warm the NH high latitudes. These excursions are ultimately terminated by Greenland melt freshwater interrupting the downwelling.
In contrast to this NH instability, the larger SH oceans and glibe-encircling southern ocean isolating Antarctica lead to slower more stable oceanography. This contrast is clearly sern in these proxy reconstructions of temperatures in Greenland and Antarctica:
http://s12.postimg.org/9ctilkusd/NGRIP_NEEM_EDC_Global_135kya.png
Sorry for the iphone fat finger typos
A useful summary – thank you
What was that massive warm period 120 to 130 thousand years ago?
Man, that was hot !
Good graph, puts things in perspective.
What was that massive warm period 120 to 130 thousand years ago?
It’s called the ‘Eemian’. Much warmer than now. But CO2 was much lower, therefore CO2 can be disregarded as a major cause of global warming.
We see that current global temperatures are nothing unusual, and that the real threat comes from global cooling:
When natural AMO and PDO ocean cycles both are in their respective 30-yr cool cycles from 2020, and as natural solar cycles continue to crash, I expect to see many more spurious papers and predictions from the warmunists suggesting manmade global warming is causing global cooling, rather than admitting the painfully obvious that the CAGW hypothesis was a complete and utter failure, and the biggest and most expensive scam in human history.
Unfortunately, there will be many Lefitsts that will continue to believe man is a scourge upon the earth, and will gleefully accept any alternative weather explanation as long as man is the cause of all calamity…
You could be correct Sam.
The global warming alarmists have utterly failed in every prediction they have made.to date, but that will not likely stop them from trying to spin their new falsehood that “global warming really means global cooling”. The warmists’ deceitful conduct to date predicates their false response.
The warmists’ honest response should be that global temperature is INsensitive to increasing atmospheric CO2, and they were completely wrong in their scary predictions of catastrophic humanmade global warming due to fossil fuel combustion.
I wrote in an article in the Calgary Herald published on September 1, 2002, based on a phone conversation with Paleoclimatologist Dr. Tim Patterson:
“If (as I believe) solar activity is the main driver of surface temperature rather than CO2, we should begin the next cooling period by 2020 to 2030.”
This now-14-year-old global cooling prediction is looking increasingly probable, plus or minus a few years. Global cooling will not be caused by atmospheric CO2 – the cause will be entirely natural.
just like the global warming we see now is entirely natural, seen the fact the LIA ended only in 1850-1900 (depending which source).
this whol cycle MWP- LIA – current warming corresponds with the holocene “bond events”: the LIA was a sudden drop of 2-2.5 degrees that lasts 300-500 years followed by a slow recover during 250-350 years. (with cyclic ups and downs in this recovering event)
so if we reached now an anomaly of +1°C, that would be entirely normal as either way which starting point you take: we’re roughly “halfway the warming cycle of that Bond event.
At the current rate, with the cyclic warming and cooling we would reach the permanent + 2°C mark somewhere around 2140 – 2180.
this is without science to back it up except all the very interesting articles and findings posted here on WUWT: when i connect the dots, i suspect if solar cycle 25 will be as weak as they forecast it, the AMO and PDO will flip both negative in the coming 5 to 10 years, we may see a 0.5 to 0.7°C drop. that if everyhing goes well in synch, then if solar activity will turn back up to the levels in 1900, it will rise again sharply with a positive amo and PDO.
lots of warmists forget that even with the much adjusted data we are now on a top of a warm cycle and just reaching the +1°C anomaly mark. it will go down for the coming 30 years. this last el nino was perhaps the warmest episode for a long time to come. unless the coming 5 years we would see another strong el nino, we aren’t going to see any “hottest year ever” s for a while…
unless they torture the data to make it worth that we are living in the adjustocene….
so seen this bond event, we are half way
yesterday I read the item at breadnbutterscience that this item contains
I found it staggering the listing of the scale of disasters way back when due to mostly…cold
it also mentions the crossover of the wind currents.
http://iceagenow.info/little-ice-ages-bring-famine-disease/#more-18416
now imagine the outcries and the insurers going broke if this was to happen in todays times.
They know the AMO will soon turn cold, which will at the very least ensure that the 18-year pause extends for another 30 yrs.
They need to prepare the ground for that.
Evil “theyists”. Whether its turns hot or cold they are evil.
When you stop using your already falsified predictions as an excuse to implement world socialism, then perhaps fewer people will think you are evil.
tony,
“Whether its turns hot or cold they are evil.”
What planet are you from? On mine, evil people controlling/exploiting vast populations is not at all unusual, it’s pretty much normal.
I’m still trying to work out exactly who some of you guys think “they” are. You’re going for socialists William?
Socialist scientists I guess?
tony mcleod commented: “…I’m still trying to work out exactly who some of you guys think “they” are….”
A common question begging an answer. Whether AGW is real or not the amount of effort and money directed to promote the narrative is massive and must come from somewhere. Personally I think “they” are mostly willing or naive useful id*ots, environmentalists, carpet baggers, crooks taking advantage, well funded NGO’s, and some wealthy patrons who have succumbed/been persuaded to the Marxist/Socialist meme after they acquired their money through Capitalism and now think their legacy (or perhaps penance) is to back a One World Government to save us. Well organized, funded, protected, and directed. Take your pick.
tony,
I’m pretty sure it’s people with enough money/power to select a given scientific hypothesis they see as useful for controlling/exploiting vast populations (like the CAGW (catastrophic anthropogenic global warming) hypothesis obviously is) and hype the hell out of it. Which ones exactly by name is not particularly relevant to me. There’s always bound to be some arrogant and ruthless ones among the hyper-wealthy elite of this world, it seems to me. And don’t get me started on the incredibly low probability that all people with degrees in some scientific realm are incorruptible angels or saints . . please ; )
markl,
” … and some wealthy patrons who have succumbed/been persuaded to the Marxist/Socialist meme …”
I feel it wise to remember, always, that the idea of socialism/communism is a fine way to convince many people to agree to handing over sweeping powers . . to people who will, once they have the sweeping power, institute whatever they feel like. It doesn’t have to actually be socialism/communism as advertised.
markl you may well be right.
However when you look at the resources of the powerful vested interest whose business model is threatened existentially by limits placed on the emission of CO2 and those resources and power are magnitudes greater then on the balance of probabilities I have to disagree with you.
tony mcleod commented: “…when you look at the resources of the powerful vested interest whose business model is threatened existentially by limits placed on the emission of CO2 and those resources and power are magnitudes greater then on the balance of probabilities I have to disagree with you….”
Except the “vested interest(s)” haven’t actively attacked the AGW meme…..have they? Those “vested interests” have donated more money to the AGW causes than the skeptics side…..no? And “maginitudes greater” is questionable when you consider many entire nations are supporting AGW. In fact the absence of the “vested interests” in the debate has been conspicuous and only a propaganda point manufactured by the alarmists.
Tony, says, “resources and power are magnitudes greater then…???
===============]
Then what Tony?
Where is your evidence that fossil fuel companies “A” are controlling the narrative, and B, have more financial backing then the combined resources of all Governments pushing CAGW alarmism?
Leif S asked for names of who “they” are. When I provided dozens of names he then changed the subject.
The great irony is that politicians demanding greater tax revenue (and political power over others) from society via the CAGW scam would, were they successful, very shortly economically destroy the source of their revenue. This has been repeated by central governments over and over throughout history. (See Brazil for the latest example)
Another irony is governments gain far more profit from fossil fuels then the companies actually doing the work, and it is now dawning on their dense minds that wind and solar companies will fail to generate any net tax revenue without massive increase in energy billing rates. Raising the cost of energy to this degree would of certainty put those societies on the wrong side of the Laffer curve, and yet again the wealth they desire to accumulate would end in tragedy. Wash, rinse and repeat for every society that turns to central authority and control of people and economies. The “invisible hand” is real and rooted in human nature, and statists ignore it at societies peril.
Reminded of something said a long time ago.
“”There are men in all ages who mean to govern well, but they mean to
govern. They promise to be good masters, but they mean to be masters.”
Noah Webster
have their cake and eat it too
Paul H says, “They know the AMO will soon turn cold, which will at the very least ensure that the 18-year pause extends for another 30 yrs.”
=======================================
Indeed, just as Mann was well aware that the AMO and PDO was taking a positive turn in the 1980s. The magicians trick is dependent on hiding the cause.
Models predicting the future are the way to riches – provided the right future is predicted
Seemingly with climate change models any future does it, right or wrong.
[snip – an ALL CAPS rant -mod]
I`m not impressed by any soothsayer talking about climate.
There are some established facts. There have been some energy uptake, and som ocean heating. Shorter timespan than 60 years is of no interest whwn we are talking of climate change.
And I think heat storage in oceans will counteract all global cooling of timespans more than 60 years.
So let`s improve statistics for the last 250 years, and take some conversation from that.
Stabilize the world’s temperature. Remove the Isthmus of Panama!
Yes indeed, I have mentioned this in the past. The Ice Ages coincide with that change in circulation. Previous, small changes in solar energy output didn’t do much but cool down somewhat, our planet.
Now, it spins out of control with vast ice sheets whenever the stellar output of energy slacks off a tad!
Low MOC events occur during negative NAO/AO episodes, and negative NAO/AO drives a warm AMO and Arctic.
http://www.rapid.ac.uk/
http://notrickszone.com/2016/06/29/u-turn-scientists-at-pik-potsdam-institute-now-warn-of-a-mini-ice-age/#sthash.baguOZQA.QlP04Wq8.dpbs
“But a fallback prediction of imminent abrupt cooling does conveniently make it rather difficult to falsify anthropogenic climate theories based on temperature alone, should global temperatures suddenly drop.”
difficult but possible. since amoc is just a heat distribution system it neither adds heat to the planet nor removes heat from the planet and so those who want to prove AGW under cooling conditions in europe must show a heat balance in which the earth is still gaining heat net of changes in ice and snow albedo effects if any.
There have also been more stories about noctilucent clouds being caused by human generated CO2 and methane. Wanna bet the next part of the story will be noctilucent clouds cool the earth?
I look at the graph from 1850 to 2016, I see minor perturbations, that’s history. I look at the graph from 2016 to 2200, I see perturbations that are magnitudes of order greater than those of 1850 to 2016. I’m going to have to go with ‘my gut’ on this one, “They currently don’t understand the climate enough for their projections to warrant consideration.”
Oh look, these “scientists” have just added a new brand of lipstick to the CAGW pig! How refreshing.
Meh, CAGW theory has covered all the bases. Warming or cooling, it’s all Man’s fault.
“evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming could be dangerous”
This is just an alarmist spin of James Hansen. What it means without the spin is Greenland glacier melting is a negative feedback that mitigates global warming. When North Atlantic cools it will cool Greenland and reduce glacier melting. AMOC will stabilize. There will be no runaway cooling nor runaway warming. It’s not dangerous
Fingers crossed Dr Strangelove.
This study found that variability in heat transport of the AMOC warms and cools the North Atlantic. The currents brought more warm during warm periods and transported less warm water during cold periods. These are shocking revelations, next they’ll discover that charcoal and ash often appear after fires.
The scientific domain is infamously limited through the application of the scientific method. Scientists need to stop conflating logical domains, substituting models/estimates for physical systems and processes, and restore a separation of the scientific from the philosophical.
Now wait, if it cools even a bit and even for a short period, the failure of the AGW hypothesis will be trumpeted by its opponents. But if the cooling might be caused by weird, mysterious, cyclical ocean currents then this conclusion is forestalled. Being on both sides of a debate means never being wrong.
Reading comprehension FAIL. Try again.
It has already failed at the rate that so called needs action taken and now over a few decades there are no signs this positive feedback from CO2 gases are there at all. 40 years is plenty long enough to show it’s FAIL and this period is almost up.