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
One of the issues the paper raised was the ENSO and volcanoes do not seem to be able to explain the drop in north Atlantic temperatures in the 1969 to 1975 period (I changed the timeline to more accurately reflect what actually happened). I certainly agree on the volcano front but I’m not so sure about the ENSO. There were some larger La Ninas in 1970, 1973 and 1975.
I’ve also speculated recently about how the AMO sometimes responds to the ENSO with a lag of about 8 months.
I’ve put together some charts to show this. Generally, the correlation is very poor (R^2 of just 0.06) but there certainly does seem to be some periods when there is a secondary affect of the ENSO on the AMO lagging about 8 months (doesn’t appear to be predictable however).
First 1979 to 2010 so one can see it a little better (also note the volcanoes don’t seem to have any impact at all on these two most important ocean cycles).
http://img163.imageshack.us/img163/7276/ensoamolag8mon1979.png
And then all the way back to 1871 which shows similar results.
http://img228.imageshack.us/img228/2963/ensoamolag8mon1871.png
Take anything generated in Boulder CO, Berkley CA and Madison WI with a grain of salt.
So it’s warming in Hiatus Port, so what?
“Doh” Homer Simpson, Atmospheric Brain
Cliff,
“They just were unable to persuade the majority of scientists that AGW is not a serious threat.”
The way I understand, it is IPCC reports that provide the climate science storey lines, which are handed down in a Mt. Sinai fashion to the rest of the world. This is not to be derogatory towards the IPCC (that would be OT), but simply to make an observation of the way things work. Is it therefore pertinent to consider that the chapters of the IPCC reports are controlled by a handful of lead authors, who have total control of the contents of these chapters.
We also need to consider that the only place in the IPCC report that addresses the question: what effect does manmade GHG’s have on the climate? occurs in one place – chapter 9 of WGI. Although about 500 authors are cited in the references, they do not write the text of this chapter (or any chapter), nor contribute to the text in any meaningful way. Indeed, many of them have written reviews highly critical of the contents of the text and conclusions drawn. Yet they have no power to change a single word.
The idea that sceptical papers are unable to convince the majority of scientists that AGW is not a threat, should thus be restated as: sceptical papers have been unable to convince the 50 lead authors and authors of chapter 9 that AGW is not a threat. But judging by the recent response of Mann and Schmidt to the M&W paper which is the latest in a long line of papers debunking Mann’s hockey sticks, I fear that nothing short of hell freezing over will convince them.
But feel free to remain worried.
Why the HadCRUT series on the monitor screen ends in 2002?
Vince,
What about the NAS report from this year? I understand all of the hubbub about the IPCC but dispatching its reports doesn’t quite dispatch AGW (or should I say, the majority science view that AGW is a serious threat). That view was taken in the NAS report. After Climategate. After the Hockey Stick fights. After all or most of the 800 skeptical papers cited above.
In particular, as to the Hockey Stick debate, if that’s all that AGW rested upon, I’d feel better. But that’s not the case. I don’t know the details of that fight, but my impression is that (a) temperature proxies and reconstructions are difficult, imperfect and (b) the two sides are now fighting over what reasonable minds can disagree about. Neither side has quite proven the other wrong anymore.
Tenuc,
Are you saying the cooling period is back in the data? Things have been pretty hot this decade. Maybe you can point me to that (not saying you’re wrong, I just don’t know where that is).
Maybe you’re saying it’s going to start real soon now – that’s fine, but is the basis for that expected lower solar activity? I keep reading there’s been no correlation between the recent warming since the 70s and solar activity. In fact I read that solar activity has been down while temperatures have been up. Or at best any solar activity cannot account for all of the warming. Do I have that wrong?
Bob Tisdale says:
September 23, 2010 at 6:49 am
Arno Arrak says: “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.”
Nope. The PDO is an aftereffect of ENSO that’s also influenced by the Sea Level Pressure of the North Pacific. Refer to:
If it is ENSO that is driving PDO, what is it that causes the ENSO to switch pattern and frequency every 30 odd years to give the phenomenon of the oscillating PDO? It could be a spontaneously emerging nonlinear pattern emerging from the system itself. Or have some solar / planetary forcing – or possibly both, a forced oscillatory nonlinear pattern.
Additionally, the North Pacific SST residuals (North Pacific SST anomalies MINUS Global SST anomalies) are inversely related to the PDO, meaning, on a decadal basis, the North Pacific contributes to Global temperatures when the PDO is negative, and subtracts from global temperatures when the PDO is positive.
Pursuing the nonlinear pattern possibility, the North Pacific SST would represent damping or friction in the global PDO related temperature oscillation (i.e. going in the opposite direction to PDO). Damping or friction is an important pre-requisite for a system to enter a regime of non-equilibrium / nonlinear emergent oscillatory pattern.
Just ideas – thanks for the solid data as usual to keep us on the straight and narrow.
“”” Richard S Courtney says:
September 23, 2010 at 11:00 am
Ben:
At September 23, 2010 at 12:24 am you say:
“Correct me if I’m wrong, but if the cooling wasn’t down to aerosols, then doesn’t that in itself invalidate most or all of the IPCC climate models…”
You are not “wrong”. Indeed, you are very, very right and this invalidation of the models has been known for a long time. “””
“””” The latter could happen, for example, if the extra energy went into a more vigorous hydrological cycle with resulting increase to low cloudiness. Low clouds reflect incoming solar energy (as every sunbather has noticed when a cloud passed in front of the Sun) and have a negative feedback on surface temperature.
Alternatively, there could be an oscillation in cloudiness (in a feedback cycle) between atmospheric energy and hydrology: as the energy content cycles up and down with cloudiness, then the cloudiness cycles up and down with energy with their cycles not quite 180 degrees out of phase (this is analogous to the observed phase relationship of insolation and atmospheric temperature). The net result of such an oscillation process could be no detectable change in sensible heat, but a marginally observable change in cloud dynamics.
However, nobody understands cloud dynamics so the reality of climate response to increased GHGs cannot be known.
Richard “””
Well Richard, I suspect the answer can be found in the paper by Frank Wentz et al; SCIENCE for July-7, 2007; “How Much More Rain will Global Warming Bring ?”
They report from actual satellite observations, that a one deg C increase in mean global (surface?) Temperature, results in a 7% increase in total global evaporation; a 7% increase in total atmospehric moisture content; and a 7% increase in total global precipitation. They also reported that the GCMs agreed with their 7% increase in total atmospheric moisture; but placed the total evap/precip at only 1-3%; not 7%. So the GCMs disagree with reality by as much as a factor of 7.
What they did not say; but which I have opned m,any times now, is that one migth treasoanbly expect a 7% increase in total global precipitation to be accompanied by maybe something like a 7% increase in total global (precipitable) cloud cover; since it is traditional to have dark clouds with your rain. That cloud increase could of course be an increase in cloud area; an increase in cloud optical density (with water content) or an increase in the cloud persistence time; or some combination of all three.
And I submit that a 75 increase in precipitable clouds is an astronomical negative feedback that would crush whatever was trying to do the one degree C temperature rise.
I have also observed that nobody has ever observed the Temperature to increase in the shadow zone when a cloud passes in front of the sun. That also is true no matter what altitude the clouds happen to be; so I do not constrain your postulate to only low clouds. High clouds also block sunlight from the surface.
the argument that high clouds warm the surface; and the higher the clouds the more the warming is just plain silly. Simple Optical theory would demonstrate that simpley isn’t possible.
And I would point out that climate is about changes that take place and persist over some considerable time (some say at least 30 years. So we are not interested in what happened to last night’s weather, because the warm humid daytime temperatures created some high wispy clouds at night when the atmosphere cooled to the dew point. I suggest those high clouds are the result of the daytimne mugginess; not the cause of it.
So in my book; any increase in total global cloud cover; no matter where the clouds are, is always a negative feedback cooling effect.
When GHGs and clouds inhibit the escape of surface emitted LWIR thermal radiation; daytime temperatures tend to increase; because the sun keeps on feeding in extra solar energy during that propagation delay for the escape of the surface radiation; and it is that extra solar input during that delay that is the cause of the warming.
But when that interception occurs at night with say high clouds; there is no sunlight to be pouring in more solar insolation, so there is no warming; just a slowing of the overnight cooling which is still going to happen. It never warms up after the sun sets; just cools slower if there are clouds; but as I said that is last night’s weather not climate.
Stephen Wilde says:
September 22, 2010 at 6:52 pm
Then one only has to introduce a bottom up oceanic forcing as observed here in this new paper and here:
http://esciencenews.com/…h.past.climate.anomalies
to see the beginnings of establishment support for my basic propositions
I would love to see papers on “bottom up ocean forcing”, internal ocean oscillation seems very compelling as a source of climate oscillation.
But your above link is broken – can we have another one?
ArndB at 6:01 am:
“…even J. Hansen et al (Science, 1981) does not object the mid century cold period : ‘In fact, the temperature in the Northern Hemisphere decreased by about 0.5°C between 1940 and 1970….’ ”
It’s a mystery how a 0.5°C decrease http://hidethedecline.eu/media/Northern%20hemisphere%20temperatures/NHNatGeo76small.jpg became a mere 0.1°C dip http://woodfortrees.org/plot/gistemp/from:1900/mean:25/plot/gistemp/from:1940/to:1970/trend.
Where is the evidence that sulphate aerosols caused cooling after 1940, then warming again due to “Clean Air Acts” of the 70’s ? 3rd world fossil fuel consumption outstripped 1st world consumption around this time. The 3rd world had no “Clean Air Acts” …
Phlogiston,
I repeated the post a bit later on with links that work. For convenience I’ll repeat it again here:
The important question is whether such cooling (or warming) events are generated by internal ocean variability which is largely independent of other factors such as events in the air.
I have proposed just that for nearly three years now – and rather tiresomely described some of the potential implications for the global energy budget and the actual climate observations.
The variations in TSI alone are clearly not enough to explain what we see and I’m with Leif Svalgaard on that.
However the effect on albedo and the energy flux generally from changes in the spectrum of energy received from the sun is a different matter.
This article has been referred to before but it is highly relevant :
http://iopscience.iop.org/1748-9326/5/3/034008/fulltext
Not everyone agrees with Leif as to a lack of potential for solar variability to have a top down effect and that paper substantially supports my propositions about the effect of solar variability on the polar oscillation, jetstream positioning, speed of hydrological cycle and albedo changes.
As you will see in the article the effect only really comes to the fore on centennial time scales which is something I have been saying for quite some time.
Then one only has to introduce a bottom up oceanic forcing as observed here in this new paper and here:
http://esciencenews.com/articles/2009/08/14/changes.net.flow.ocean.heat.correlate.with.past.climate.anomalies
to see the beginnings of establishment support for my basic propositions
I found myself thinking that if this coincided, as stated by Jones, with a large influx of cold non-saltwater from the Arctic, that the obvious candidate is some kind of under ice volcanic warming (not necessarily an eruption) melting a large amount of arctic ice at one time to pour all that fresh cold water into the Atlantic.
It once again does make me wish the satellite coverage of the Arctic started sooner than 1979. . .I wonder what the extents would have looked like 1968-1979 given this information?
George E Smith
September 23, 2010 at 8:56 am
I’m not sure that it is necessary for a faster hydrological cycle to produce more clouds overall. If the whole cycle speeds up to retain global optical depth as it does seem to do then rather than having more clouds one just sees the water in cloud form for a shorter period of time before it falls to Earth.
I don’t necessarily contend that there is NO change in total cloudiness, there may well be some but on it’s own I didn’t see the cloudiness change as an adequately large enough or obvious enough effect on it’s own to achieve the observed change in the overall energy budget.
Hence my suggestion that the factor most likely to have a large enough effect would be a change in albedo for the entire globe resulting from a change in the angle of incidence of solar input onto the clouds when all the air circulation systems and all the associated clouds shift latitudinally.
Unfortunately there is currently no adequate data to resolve that issue definitively.
It’s the music of the spheres, keeping everything in time.
At the top level we have grand minima controlled by the Neptune/Uranus 172 yr cycle, the current solar slowdown is right on track as predicted.
The next level down is the 60 year cycle controlled by Jupiter/Saturn that as Scafetta has noticed sync’s with the PDO. Both of these cycles are working together but can experience a phase change as we saw during the MWP. Also the amplitude of the 60 year cycle is governed by the 172 yr cycle. Notice how the PDO modulation is weaker when N/U are apart.
The next level down is the atmospheric teleconnections (NAO, AO, SAM etc), which look to align themselves with solar UV output which of course is related to the first cycle.
“”” Stephen Wilde says:
September 23, 2010 at 3:01 pm
George E Smith
September 23, 2010 at 8:56 am
I’m not sure that it is necessary for a faster hydrological cycle to produce more clouds overall. “””
Well I don’t know where you got that “faster hydrological cycle stuff from; I certainly said nothing about it. It seems like something that you and Dr Judith Curry understand between you.
I’m rather simple minded. If I expect to get more rain; I also expect to get more clouds; simple as that.
If you can get precipitation without clouds; then good for you; I can’t.
Cliff, the difference is, one side admits this shortcoming of knowledge, and the other is forecasting impending doom with absolute certainty (using the same information). As no doom-sayer has been correct (we are still here), I know which horse I am backing. The honest, conscientious, humble, hard-working, straight shooting (shall I go on?) side. Try peddling the fence sitting position over at RC or DePropaganda blog and see how far you get.
It was ocean cooling!
If El Niño will be more frequent because of CO2, then we are to believe CO2 also causes a rise in SSTs? What caused the ocean to cool? I didn’t catch the explanation of that…
Hi George E. Smith, I just wanted to chime in real fast. It is possible that the hydrological cycle could speed up with less clouds if the amount of precipitation per event increased faster than the frequency of the events decreased. I don’t think that is at all likely, but it is possible.
David,
“Cliff, the difference is, one side admits this shortcoming of knowledge, and the other is forecasting impending doom with absolute certainty (using the same information). ”
Respectfully, that’s a bit of an overstatement or at least overgeneralization. Even the IPCC talks in terms of what is likely or very likely, not a certainty. Also, the NAS report from this year is much more restrained than your characterization. But then I can’t get a single person here to acknowledge or deal with that report.
“As no doom-sayer has been correct (we are still here), I know which horse I am backing.”
But even the extreme doomsayers are talking about the future. Not current conditions.
“The honest, conscientious, humble, hard-working, straight shooting (shall I go on?) side. “. Really, all those authors of the NAS report and yes the IPCC reports are dishonest and arrogant? I find that really hard to believe.
Wow! They’ve finally noticed that it was bloody cold a lot of the time in the 1970’s and not just in the northern hemisphere.
This surely must go down in the annals of science as a historic discovery and must surely be a consideration for at least another 3 year’s worth of grants.
And it was bloody cold here down under as well but what would I as an ordinary old Australian country farmer who had to live and work and make a living out in the that 1960’s and 70’s weather actually know about the climate of the times?
And I don’t have a number of letters after my name so I guess I would have to produce reams of data to support my claims.
Sigh! Could have been so easy if I had got a corn flake packet degree in climate science.
Make a claim, no backup verification data required as I had all those letters after my name and therefore was a leading authority on any subject so couldn’t be doubted.
Much, much easier and far more profitable farming for tax payer’s grant money than farming to grow food and you can do it from an airconditioned office.
I’m late to the party but the banshee bit covered by PaulH
September 22, 2010 at 6:55 pm, really grated me too. Like chalk scraping a blackboard or a banshee screaming.
Cliff says:
September 23, 2010 at 6:20 pm
“The honest, conscientious, humble, hard-working, straight shooting (shall I go on?) side. “. Really, all those authors of the NAS report and yes the IPCC reports are dishonest and arrogant? I find that really hard to believe. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~That is quite a leap , Cliff 🙂 and cleverly avoiding the point of my post.