Warming since 1950s partly caused by El Niño
HUNTSVILLE, Ala. (Nov. 11, 2013) – A natural shift to stronger warm El Niño events in the Pacific Ocean might be responsible for a substantial portion of the global warming recorded during the past 50 years, according to new research at The University of Alabama in Huntsville (UAH).
“Our modeling shows that natural climate cycles explain at least part of the ocean warming we’ve seen since the 1950s,” said Dr. Roy Spencer, a principal research scientist in UAH’s Earth System Science Center and the new study’s lead author. “But we also found that because the globe has had more frequent La Niña cooling events in the past ten or fifteen years, they are canceling out some of the effects of global warming.”
The paper detailing this research, “The Role of ENSO in Global Ocean Temperature Changes During 1955-2011 Simulated with a 1D Climate Model,” is scheduled for publication in the Asia-Pacific Journal of Atmospheric Science, and is available online at:
http://link.springer.com/article/10.1007/s13143-014-0011-z.
The results also suggest the world will warm by 1.3 C (about 2.34° F) from a doubling of atmospheric CO2, which is only one-half of the warming expected by most climate researchers.
General circulation climate models — such as those used to forecast global climate change — do not reproduce the tendency toward 30 year periods of stronger El Niño or La Niña activity, as are seen in nature.
Spencer and co-author Dr. Danny Braswell used all of the usual climate modeling forcings — including carbon dioxide and other greenhouse gas enrichment — in their study, but also plugged the observed history of El Niño ocean warming and La Niña ocean cooling events into their model to calculate the 61-year change in global ocean temperature averages from the sea surface to a depth of 2,000 meters.
“We used the observed ENSO (El Niño Southern Oscillation) history since the 1950s as a pseudo forcing factor of the model,” Spencer said.
When they ran their ocean model without ENSO, they arrived at the same general conclusions as the more complex general circulation climate models. When they added data from past El Niño and La Niña events as only a change in ocean mixing, the model indicated a climate system that is slightly less sensitive to CO2-induced warming than has been believed.
But the biggest change was when the model was allowed to change cloud cover with El Niño and La Niña in the same way as has been observed from satellites. The results suggest that these natural climate cycles change the total amount of energy received from the sun, providing a natural warming and cooling mechanism of the surface and deep ocean on multi-decadal time scales.
“As a result, because as much as 50% of the warming since the 1970s could be attributed to stronger El Niño activity, it suggests that the climate system is only about half as sensitive to increasing CO2 as previously believed”, Spencer said.
“Basically, previously it was believed that if we doubled the CO2 in the atmosphere, sea surface temperatures would warm about 2.5 C,” Spencer said. That’s 4.5° F. “But when we factor in the ENSO warming, we see only a 1.3 C (about 2.3° F) final total warming after the climate system has adjusted to having twice as much CO2.”
It was previously known that Pacific Ocean warming and cooling events come and go in roughly 30-year periods of predominance, where El Niño warming events are stronger than La Niño cooling events for approximately 30 years, followed by roughly three decades where the reverse is true.
During the period of this study, cooling events were dominant from the 1950s into the late 1970s. That was followed by a period of strong El Niño warming activity that lasted into the early 2000s. The current phase has seen increased La Niña cooling activity.
Spencer said it is reasonable to suspect that the increased La Niña cooling might be largely responsible for an ongoing “pause” in global warming that has lasted more than a decade. If that is the case, weak warming might be expected to revive when this phase of the El Niño-La Niña cycle shifts back to a warmer El Niño period.
The study was the result of a debate over whether clouds can be part of an active forcing mechanism for global warming, or are just a passive response to temperature change.
“What we found is, to explain the satellite data we had to invoke a change in clouds nine months before the peak of either an El Niño or a La Niña,” Spencer said. “When the clouds change, it takes time for that to translate into a temperature change.
“We get the best fit to the observations when we let clouds cause some of the temperature change. These cloud changes are occurring before the temperature starts to respond, so they can’t be caused by the temperature changes.”
Before an El Niño Pacific Ocean warming event, global cloud cover decreases, allowing more solar energy to reach the Earth’s surface and be converted into heat. On the flip side, before a La Niña Pacific Ocean cooling event, cloud cover increases, shading more of the Earth’s surface and reflecting an increased amount of solar energy back into space.
While changes in cloud cover intensify the warming or cooling of these ocean events,
Spencer and Braswell still found that two-thirds of the sea surface temperature changes during both El Niño and La Niña events are driven by changes in ocean mixing. But the one-third forcing by clouds turns out to be an important component, substantially changing our interpretation of how sensitive the climate system is to CO2 emissions.
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The role of ENSO in global ocean temperature changes during 1955–2011 simulated with a 1D climate model
Abstract
Global average ocean temperature variations to 2,000 m depth during 1955–2011 are simulated with a 40 layer 1D forcing-feedback-mixing model for three forcing cases. The first case uses standard anthropogenic and volcanic external radiative forcings. The second adds non-radiative internal forcing (ocean mixing changes initiated in the top 200 m) proportional to the Multivariate ENSO Index (MEI) to represent an internal mode of natural variability. The third case further adds ENSO-related radiative forcing proportional to MEI as a possible natural cloud forcing mechanism associated with atmospheric circulation changes. The model adjustable parameters are net radiative feedback, effective diffusivities, and internal radiative (e.g., cloud) and non-radiative (ocean mixing) forcing coefficients at adjustable time lags. Model output is compared to Levitus ocean temperature changes in 50 m layers during 1955–2011 to 700 m depth, and to lag regression coefficients between satellite radiative flux variations and sea surface temperature between 2000 and 2010. A net feedback parameter of 1.7Wm−2 K−1 with only anthropogenic and volcanic forcings increases to 2.8Wm−2 K−1 when all ENSO forcings (which are one-third radiative) are included, along with better agreement between model and observations. The results suggest ENSO can influence multi-decadal temperature trends, and that internal radiative forcing of the climate system affects the diagnosis of feedbacks. Also, the relatively small differences in model ocean warming associated with the three cases suggests that the observed levels of ocean warming since the 1950s is not a very strong constraint on our estimates of climate sensitivity.
Dr Norman Page says:
“Check the Christiansen paper..”
Yes lots of polar locations, and check Fig 3 for non polar locations, there’s some with cooling around 1000 AD.
– – – – – – – –
Don Easterbrook,
You have provided a view toward a critical deficiency in the model.
The prior geological knowledge (on all of its timescales) that should be a necessary basis for the model (its priors) appears to be lacking. Therefore it is reasonable to think the model does not have sufficient available knowledge as its grounds.
John
RE the CET (Central England Temp) record.
The CET record from 1650-2013 is indeed remarkable. Virtually every known warm/cool period shows up very nicely if you expand the vertical scale a bit so you can see the variable temps. In a nutshell, here is what it records:
1650-1700 Maunder Minimum cooling
1700-1735 Warming
1735-1770 Cooling
1770-1780 Warming
1780-1820 Dalton Minimum cooling
1820-1835 Warming
1835-1845 Cooling
1845-1875 Warming
1875-1895 Cooling
1895-1900 Warming
1900-1920 Flat
1920-1950 Warming
1950-1975 Cooling
1975-2005 Warming
2005-2013 Cooling
All of these warm/cool periods are well known from other records.
Don Easterbrook says:
“RE the CET (Central England Temp) record.
All of these warm/cool periods are well known from other records.”
See how many of those warming and cooling periods are the inverse of what Greenland was doing:
http://www.21stcentech.com/wp-content/uploads/2012/07/Greenland-ice-core-data.png
Use the actual figures for more precision would help:
http://climexp.knmi.nl/data/tcet.dat
Ulric
Perhaps I am reading your comments out of context. What is the point you wish to make about CET and about Greenland?
Tonyb
Roy Spencer writes;
The first few columns of Table 9.5 from AR5 here;
http://www.friendsofscience.org/assets/documents/CanESM/Table9.5_AR5.jpg
shows the mean equilibrium climate sensitivity for double CO2 of the 30 climate models evaluated by the IPCC is 3.2 deg. Celsius.
Well, 2.2 C is only 69% of the model mean of 3.2 C. I would say that is a lot below, not “somewhat below”, the average of the IPCC models.
All the senior IPCC scientists are adamant that cloud cover can only change in response to a temperature change, that is, they only changes as a feedback response. This paper shows that clouds change before a temperature change, so act as a forcing agent. This is an extremely important result.
The ENSO process causes clouds to change, causing a temperature change.
climatereason says:
“Perhaps I am reading your comments out of context. What is the point you wish to make about CET and about Greenland?”
In this instance the chronology of the MWP, was it Crispin Tickell who chose to use the warm period in Greenland as a direct proxy for Central England from 1195 to 1375? I’m sure I saw somewhere that Lamb noted a cooler period for England starting from around 1200.
Ulric Lyons says:
November 12, 2013 at 7:58 pm
Based upon the chronicles, I’d say the 1250s started to show signs of climatic deterioration. The early 1300s were also bad, but there were still warm decades mixed in during the waning century-plus of the Medieval Warm Period.
Every centuries-long “warm” & “cold” “period” naturally has counter-trend fluctuations annually & by decade. But the depths & peaks in the LIA or Dark Ages Cold Periods are cooler than those in the Roman, Medieval or Modern Warm Periods. Climatic parameters change constantly naturally, fluctuating annually & by decade, which is weather, & by the averages of decades, centuries, millennia & longer intervals & over various regions, which is climate.
JohnWho says: @ur momisugly November 12, 2013 at 6:25 am
It’s logarithmic all the way…..
I originally asked the question because I am under the impression that this concept discusses CO2 in a “pure state” with no other gasses also absorbing IR radiation. With the other gasses present in our atmosphere, there is only so much radiation left for CO2 and there is a point where it absorbs all it can: a “saturation” point.
>>>>>>>>>>>>>>>>>>>>>>
Math models can be used to describe physical responses over a limited range.
On Saturation Point: Support for the saturated greenhouse effect… “…a new paper that supports Miskolczi’s theory of saturated greenhouse effect…. The consequence of the Miskolczi theory is that additions of ‘greenhouse gases’ such as CO2 to the atmosphere will not lead to an increase in the ‘greenhouse effect’ or increase in global temperature…. “
Ulric Lyons
I am currently engaged in reconstructing CET from 1659 to 1086 and am presently at 1538. Obviously it gets much more difficult as I go further back in time. I definitely agree with the CET cooling around 1200 which lasted sporadically for some time, although we can then pick up again on warming during much of the 1300’s, then probable cooling towards the end of the 14th century but then renewed warmth again.
As has been noted elsewhere, warm periods such as the MWP can be punctuated by frequent downturns and similarly the LIA is punctuated by many upturns (such as the 1700 to 1740 period.)
Dr Mann’s chronology appears incorrect which is why I try to compare His and Lambs reconstructions in my article.
tonyb
JohnWho says:
November 12, 2013 at 6:25 am
If logarithmic “all the way”, then there is never a time when additional CO2 doesn’t have some effect, even as it gets extremely minor. Well, all the way until we have a pure 100% CO2 atmosphere. I originally asked the question because I am under the impression that this concept discusses CO2 in a “pure state” with no other gasses also absorbing IR radiation. With the other gasses present in our atmosphere, there is only so much radiation left for CO2 and there is a point where it absorbs all it can: a “saturation” point. Are we close to that or am I under a misunderstanding?
The only misunderstanding I’ve talked about or really can talk about is the idea that if the response is logarithmic, this means that “each doubling has progressively less effect.” It’s not true. With logarithmic response, each doubling has the same effect, because:
log(2x/x) = log(4x/2x), i.e., log(2) = log(2)
What’s true is that each increase of the same size has progressively less effect. For example, 560->840 has a smaller effect than 280->560 (note that 840-560=280).
Oops. looks like I didn’t terminate the boldface. Just testing now to see how this message appears. If it appears in boldface, I apologize.
tonyb:
Mann’s error was in saying that the Arctic and the north temperate zone temperatures move in unison. Unfortunately this false model has infected the whole of contemporary climate science.
And I would like to thank you for the vital work you are doing in collating historical records to allow greater accessibility to our weather history, it often only takes one, well done.
@ur momisugly All who have responded to my post of November 12, 2013 at 6:25 am –
Thanks you for your responses.
I am getting the feeling that there is a consensus (hate to use that word) that there is a “saturation point” regarding atmospheric CO2 although the exact amount of CO2 that reaches the saturation point remains under discussion. 400 ppm may well be beyond that point, however.
In a perfectly stable, nitrogen and CO2 only example, the logarithmic numbers would hold true up to 100% CO2. However, in an ever-changing, turbulent, chaotic environment such as the Earth’s atmosphere which also includes water vapor, methane, nitrous oxide, and ozone, we might not come even close to the mathematically computed model CO2 warming.
Am I getting, uh, warmer?
🙂
I would just remind everyone again that the IPCC have given up on estimating CO2 climate sensitivity
By AR5 – WG1 the IPCC is saying: (Section 9.7.3.3)
“The assessed literature suggests that the range of climate sensitivities and transient responses covered by CMIP3/5 cannot be narrowed significantly by constraining the models with observations of the mean climate and variability, consistent with the difficulty of constraining the cloud feedbacks from observations ”
In plain English this means that they have no idea what the climate sensitivity is and that therefore that the politicians have no empirical scientific basis for their economically destructive climate and energy policies.
The whole idea of climate sensitivity to CO2 is illogical because CO2 follows temperature. – it is like trying to calculate the sensitivity of the sun to the tan.
Dr. Spencer now appearing in Science Daily,
http://www.sciencedaily.com/releases/2013/11/131113152538.htm