NOTE: As is typical these days, and in keeping with co-author Phil Jones tradition of not giving up anything, the publicly funded scientific paper is not included with the news, and is hidden behind a paywall. All we can get is the press release and abstract and this silly picture of the researcher grinning like a banshee. Speculate away with impunity. I wonder why he has the ozone hole in Antarctica next to the HadCRUT temperature series?
Caption: David W.J. Thompson, professor of atmospheric science at Colorado State University, is the lead author of a Nature paper that shows sudden ocean cooling contributed to a global warming hiatus in the middle 20th century in the Northern Hemisphere. Credit: Colorado State University
FORT COLLINS – The hiatus of global warming in the Northern Hemisphere during the mid-20th century may have been due to an abrupt cooling event centered over the North Atlantic around 1970, rather than the cooling effects of tropospheric pollution, according to a new paper appearing today in Nature.
David W. J. Thompson, an atmospheric science professor at Colorado State University, is the lead author on the paper. Other authors are John M. Wallace at the University of Washington, and John J. Kennedy at the Met Office and Phil D. Jones of the University of East Anglia, both in the United Kingdom.
The international team of scientists discovered an unexpectedly abrupt cooling event that occurred between roughly 1968 and 1972 in Northern Hemisphere ocean temperatures. The research indicates that the cooling played a key role in the different rates of warming seen in the Northern and Southern Hemispheres in the middle 20th century.
“We knew that the Northern Hemisphere oceans cooled during the mid-20th century, but the sudden nature of that cooling surprised us,” Thompson said.
While the temperature drop was evident in data from all Northern Hemisphere oceans, it was most pronounced in the northern North Atlantic, a region of the world ocean thought to be climatically dynamic.
“Accounting for the effects of some forms of natural variability – such as El Nino and volcanic eruptions – helped us to identify the suddenness of the event,” Jones said.
The different rates of warming in the Northern and Southern Hemispheres in the middle 20th century are frequently attributed to the larger buildup of tropospheric aerosol pollution in the rapidly industrializing Northern Hemisphere. Aerosol pollution contributes to cooling of the Earth’s surface and thus can attenuate the warming due to increasing greenhouse gases.
But the new paper offers an alternative interpretation of the difference in mid-century temperature trends.
“The suddenness of the drop in Northern Hemisphere ocean temperatures relative to the Southern Hemisphere is difficult to reconcile with the relatively slow buildup of tropospheric aerosols,” Thompson said.
“We don’t know why the Northern Hemisphere ocean areas cooled so rapidly around 1970. But the cooling appears to be largest in a climatically important region of the ocean,” Wallace said.
Global temperatures 1850-2010 [Nature News]
An abrupt drop in Northern Hemisphere sea surface temperature around 1970
David W. J. Thompson1, John M. Wallace2, John J. Kennedy3 & Phil D. Jones4
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA
- Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195-1640, USA
- Met Office Hadley Centre, Met Office, Exeter EX1 3PB, UK
- Climatic Research Unit, University of East Anglia, Norwich NR4 7TJ, UK
Correspondence to: David W. J. Thompson1 Email: davet@atmos.colostate.edu
Abstract
The twentieth-century trend in global-mean surface temperature was not monotonic: temperatures rose from the start of the century to the 1940s, fell slightly during the middle part of the century, and rose rapidly from the mid-1970s onwards1. The warming–cooling–warming pattern of twentieth-century temperatures is typically interpreted as the superposition of long-term warming due to increasing greenhouse gases and either cooling due to a mid-twentieth century increase of sulphate aerosols in the troposphere2, 3, 4, or changes in the climate of the world’s oceans that evolve over decades (oscillatory multidecadal variability)2, 5. Loadings of sulphate aerosol in the troposphere are thought to have had a particularly important role in the differences in temperature trends between the Northern and Southern hemispheres during the decades following the Second World War2, 3, 4. Here we show that the hemispheric differences in temperature trends in the middle of the twentieth century stem largely from a rapid drop in Northern Hemisphere sea surface temperatures of about 0.3 °C between about 1968 and 1972. The timescale of the drop is shorter than that associated with either tropospheric aerosol loadings or previous characterizations of oscillatory multidecadal variability. The drop is evident in all available historical sea surface temperature data sets, is not traceable to changes in the attendant metadata, and is not linked to any known biases in surface temperature measurements. The drop is not concentrated in any discrete region of the Northern Hemisphere oceans, but its amplitude is largest over the northern North Atlantic.
=============================
hmmm, maybe this graph from ICECAP will help them:
And this too:
The historical variability of the Arctic Oscillation. 1969-1970 was darned cold.
Also see this image from the Climate Prediction Center:
ALSO: Quote from Phil Jones: Reuters
Jones, at the centre of a furore over e-mails hacked from the University of East Anglia in late 2009, was reinstated this year after reviews cleared him of suspicions of exaggerating evidence in favour of global warming.
Thursday’s paper is the first he has since published in Nature. “Maybe it will get them thinking,” he said, asked how climate sceptics would react to his involvement in a paper highlighting a cause of cooling, rather than warming.
——————-
I wonder how good that Southern Hemisphere SST data is back in the 1960s, which is used here to demonstrate “robustness”. From Physicsworld.com
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I think they are trying to lay the groundwork for an excuse they can apply to the approaching global warming hiatus.
Wasn’t that period of cooling previously blamed on aerosols? And the warming that followed was said to be due to the reduction of aerosols due to pollution controls. If that’s not the case then obviously the GCMs are wrong.
What a shock.
That period of cooling couldn’t possibly be due to natural variability, could it? 😉
I, for one, enjoy the cold. Or a warming hiatus or whatever Dr. Backpeddle wants to call it after a 30 year warming period. I had a LOT of fun in the snow of the 70’s. My son loves what he calls “tobogalling”. Always look for the silver lining. Cheers.
Perhaps the effects of aerosol particles was enhanced or multiplied in some means, thereby creating sudden tipping points at which its effects are magnified in a sudden or catastrophic fashion. Isn’t that how the gradual increase of CO2 is supposed to create ocean level rises of 20 meters or whatever?
q/ I wonder why he has the ozone hole in Antarctica next to the HadCRUT temperature series?unq
Because he is an idiot???
regards.
(and no apologies)
Max Hugoson said:
“one still has to explain WHY they would engage in a massive “turn over” and decide to drop temperatures down (absorb significantly more energy than in previous years…)”
More pertinently one would need to explain why a vast body of liquid with an internal system of movement (probably variable) and large areas of temperature and density differentials subject to the rotational forces set up by the planet and affected by highly variable winds would NOT engage in massive changes in “turnover”.
Such changes would be trivial for the oceans but massive for the air due to the density differential between water and air.
The rate of energy absorption by the oceans would be induced primarily by albedo changes as the main cloud bands shift latitudinally on centennial time scales.
The rate of energy release by the oceans would be induced by internal ocean cycling.
What is important about this paper is that these pro-AGW climate scientists to date are recognizing that there are profound natural variations in the climate (mostly driven by unexplainable ocean cycles).
The IPCC reports really downplayed this natural effect but these scientists are confirming that the natural cycles are very important. Having Phil Jones and John J. Kennedy (in charge of ocean SSTs and HadSST at the Met Office) sign off and confirm this finding is a major event in climate science.
It will be disputed (and the quotes from other scientists show this in less than 24 hours) but it should signify a change in philosophy.
Once one goes down this road, the 1976 to 1998 warming period then starts to look more like 50% caused by natural warming. Climate models have to be rewritten and the CO2 sensitivity is reduced by 50% of that previously assumed.
It is a significant event having prominent pro-AGW scientists recognize ocean cycles that cannot be caused by the other typical climate forcings of GHGs, aerosols, volcanoes or the ENSO. It is perfectly reasonable but the community has not been able to make this leap before.
Douglas, you’ld be right ’bout that. The only time I get to enjoy fried steak-sized green toms is when it’s witch-tit cold in August and Septmeber.
That picture is so garbage…
The Mann hockey stick and the Ozone hole…
Thompson is quite a work of art… dart board quality…
REPLY: It’s HadCRUT temperature, not the Mann Hockey Stick – Anthony
It has been a circuitous and costly journey back to what we have known for 30 years. Or is it just me, …..
His grin looks quite sheepish to me.
tom says:
September 22, 2010 at 7:41 pm
I think they are trying to lay the groundwork for an excuse they can apply to the approaching global warming hiatus.
…………………………………………………………….
True story… i know some of the folks in Co. they are throwing out fishing lines in all directions…
This is not the only oceanic phenomenon affecting climate but it is good to see it getting attention. Another one in the Pacific is the PDO which may or may not be related to it in some way. That is because PDO may be influenced by the terminus of the thermohaline circulation which starts in the North Atlantic and snakes south from there along the bottom of the ocean. But when it comes to the North Atlantic temperatures it is abundantly clear that any temperature shift there implies a change in the Gulf Stream. The Gulf Stream comes up along the North American east coast and then turns east and broadens out into the North Atlantic drift. From there its branches spread out towards the North Sea and towards the Arctic Ocean which is reached by passing between Iceland and Scandinavia. This arctic branch of the Gulf Stream keeps the Russian Arctic ice free as far as Novaya Zemlya and beyond. After cooling its water sinks and contributes to the thermohaline circulation, a cold current moving south along the bottom of the ocean. To cool the North Atlantic you either have to slow this system down at some point or to divert it south towards the Bay of Biscay. In either case the Russian Arctic would be affected which should have been checked. Unfortunately I don’t see that any of these possibilities were checked by the authors who seem to be oblivious to what controls the temperature of the North Atlantic. This is par from people who don’t even know that warm currents of the North Atlantic, chiefly the Gulf Stream, are the cause of Arctic warming. It started abruptly at the turn of the twentieth century after a two thousand year, linear, cooling stretch (Kaufman et al., Science 325:1236-1239). This sudden start of warming rules out carbon dioxide as the causative agent despite what Kaufman et al. think about their own discovery. Laws of physics simply don’t allow it. Only a rearrangement of the North Atlantic current system at the turn of the century is capable of suddenly delivering the massive amounts of heat that began to pour into the Arctic at that time. This is one crucial period in the history of the Atlantic that should be studied but nothing has been done so far even though this information has been available since last December. A lesser amount of warm water flowing through the Bering Strait also contributes to Arctic warming. In 2007 more than the usual amount of warm water entered the Arctic this way and melted a large patch of ice on the west side of the ocean while the Gulf Stream side hardly changed. Read:
http://www.amazon.com/What-Warming-Satellite-global-temperature/dp/1439264708/ref=sr_1_1?s=gateway&ie=UTF8&qid=1285209232&sr=8-1
tom says: September 22, 2010 at 7:41 pm
“I think they are trying to lay the groundwork for an excuse they can apply to the approaching global warming hiatus.”
You think so!
ps. “approaching global warming hiatus” should be “ongoing cooling phase of the global climate cycle”
Perhaps Mr/Dr Thompson could explain WTF happened to the Little Ice Age in the Hokey-Schtick graph on his computer screen. As we all at WUWT know, that event was a). REAL, and b). A cooling that didn’t come on “suddenly” but managed to linger for nearly 300 years. Gee, whatever might have caused that?
These Calamit(y)-ologists seem to think they can replicate the past if they just twiddle the GCM knobs a little here and there. But they still can’t explain the 1900-1940 warming because CO2 is the only knob they have for “heat”.
Just another $50-$100 Bn in “research” funding ought to do the “trick”.
“We don’t know why the Northern Hemisphere ocean areas cooled so rapidly around 1970. But the cooling appears to be largest in a climatically important region of the ocean,” Wallace said.
“While the temperature drop was evident in data from all Northern Hemisphere oceans, it was most pronounced in the northern North Atlantic, a region of the world ocean thought to be climatically dynamic.”
====================================
Idiots! No mention at all in the press release of the Pacific Decadal Oscillation or the Atlantic Multidecadal Oscillation where, during 1970, both were in the troughs of those waves.
How ******* stupid do they think we are?
Keep grinning. The grin reminds me of Gavin in the coffee shop in NYC.
Chris
Norfolk, VA, USA
There’s a healthy, detailed discussion of the paper and its implications on Dot Earth: http://dotearth.blogs.nytimes.com/2010/09/22/a-sharp-ocean-chill-and-20th-century-climate/
Where is it written that only one potential impact can act at a time? North American sulfate emissions peaked around 1974 — why can’t that have added to the PDO? Sulfate emissions might have climbed a bit more in the FSU, but it is US sulfate emissions that could cool the adjacent Atlantic.
“We knew that the Northern Hemisphere oceans cooled during the mid-20th century, but the sudden nature of that cooling surprised us,” Thompson said.
These fellows should stop saying they are surprised by things. It only shows how little they know—I think they don’t understand that.
I’m particularly fond of this phrase – “cooling played a key role in the different rates of warming “
This is actually quite a significant result, given its publication in Nature. For years, the CAGW true believers have been claiming that the mid 20th century cooling (which led to the abortive “global cooling” panic in the mid 70’s) was a result of the cooling effects of anthropogenic aerosols masking the greenhouse gas-induced warming. Now we have, in Nature, the warmists’ favorite tabloid, a paper, co-authored by none other than Climategate Phil, that implies an oceanic oscillation was the driver. If oceanic cycles can cause cooling – gee, I dunno Phil, do ya think they could also cause warming?????
But watch, instead the CAGW zealots will now use this result to somehow claim that climate sensitivity has therefore been underestimated and …… it’s worse than we thought!!!! Long live CAGW cargo cult science.
Here comes the return of reason, it will be painful.
To everyone.
It will be blamed on the oceans, those dastardly ocean cycles convinced our leaders the end was near.
But, now it is clear, it is cyclic.
Who knew?
Actually, without reading the paper yet, I see this as very positive erosion of AGW. Aerosols have been “eruditely” tossed about to account for all temperature deviations that differ from the Keeling curve despite very very flimsy data. I suspect we will soon see a few papers that show aerosols as insignificant. So natural variation is all that’s left and they need to look like they are on top of things even when they are out of ammunition.
may have been
I am so sick of this.
It would appear from the Law Dome ice core data CO2 increase took a 20 year hiatus around the same time.