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.
Fancy running a sweepstake on how many hours will pass before the APJAS editor carries out a pre-publication retraction and then resigns in shame at letting this paper nearly get through the gates? Put me down for 48.
Roy Spencer says:
As I mention on my blog, others have indeed “known” about this, but we put actual numbers in an energy-conserving model to show that there is more radiant energy coming in during El Nino, about 0.6 W/m2 per unit MEI Index value.
And you got it published.
Thanks.
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.
It is good to see the cloud cover getting more attention. It would be nice to think that the authors had been reading Willis Eschenbach. Still, this is just another model. If it makes predictions for the future, or other out of sample data, then it can be tested.
With the Earth surface being warmer now than in 1950, it’s possible that sensitivity to future CO2 is even lower.
Dr Norman Page says:
November 11, 2013 at 1:13 pm
Thanks for the comparison in your Fig 4 between reconstructed CO2 levels & paleoclimatic proxy temperature observations during the Holocene. Would you attribute the apparent rise in CO2 during the LIA to a lag effect from the oceans heated during the preceding Medieval Warm Period?
The ENSO affects the global temperature.
That is the most obviously true statement there is regarding the climate. I mean, other than the Sun heats the Earth, there is no more clear example of a fact that cannot be disputed than that.
Now why climate science finds it so hard to work with can only be described as deliberate wilful ignorance. Which is the worst thing that can be done in science period.
Joseph Bastardi: How is this some brilliant finding
It permits a quantitative estimates of the ENSO cloud effects and the purported CO2 effect, and the 9-month lag is new. Whether it is “brilliant” depends on how well the model does against out-of-sample data. And it has been published in the peer-reviewed literature where more graduate students are likely to find it and write about it. Now that it has been publlshed, there is a good chance that it will be elaborated in fairly obvious ways, such as separating N and S hemispheres, adding other known and hypothesized energy flows, and so on.
Surely you would not object to newer nails being introduced into the market place just because everyone already knows that nails are useful?
““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.””
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Hmmm, “when we let clouds cause some of the temperature change” — interesting.
What would happen if you don’t let CO2 do any of the warming?
Oh yeah, I forgot, nothing gets published at all.
Jim Cripwell: Roy does not go far enough. We can take into account all natural forcings by noting that Beenstock et al and Mora et al have shown that there is no CO2 signal in any modern temperature/time graph. So it follows that there is a strong indication that the CS of CO2 is indistinguishable from zero.
Like everyone else, Beenstock et al (whose paper prompted me to buy two new books on that statistical technique) may be wrong. Their model is strictly a vector autoregressive model with no energy flows or other physical phenomena that might be in the full causal picture. This model here quantifies for the first time the actual energy flows controlled by the cloudiness changes produced by ENSO. Others, perhaps including Spencer, can go farther now that this has worked as well as it has and has been published. I don’t think it is realistic to expect that one paper is ever going to be so influential as to settle the policy and scientific debates. I think that Spencer and Braswell are to be applauded for taking a good step forward.
I’ll give Judith’s blog a try on Friday. Thanks Joe, I’ll take a look at that but not so sure that’s a good explanation as water absorbs a great deal of energy around those wavelengths as well. Which would further diminish the impact of increasing CO2 levels.
AND, half of a small number is yet a SMALLER number …
Steven Mosher: a 1.3C TCR translates into a 2.6C ECS.. thereabouts
That depends on assumptions, and even then requires a derivation rather than a bald assertion. And the time scale matters: if the response of the surface to a doubling of CO2 is fast, then TCS of the surface is the ECS of the surface (thereabouts), and if the response of the deeper ocean requires another 1,000 years to be nearly complete, the entire public policy debate is changed. The history of the climate is a series of transients, and the concept of the “equilibrium” has never been shown to be pertinent to a system that can’t have an equilibrium.
Steven Mosher: 2. CS for C02 cannot be zero or close to zero
It depends on the state of the climate at the time that CO2 concentration is rising. Starting where the climate is now, it is possible that doubling the concentration from 400 to 800 will have no net effect on global mean temperature.
Without wanting to sound too critical but a 40 layer one dimensional model mmmmm! That will assume a constant effect over the entire three dimensional globe or at a minimum over the region or zone that ENSO is operating which seems a stretch given the model’s limited dimensionality. Or am I missing something (not saying ENSO does not have an effect)? But has the model been verified and validated or is this another tongue-in-cheek simulation.? Can’t say I’m overwhelmed by the results or conclusion. Not all that convincing at present it just seems to want to confirm the IPCC that sensitivity is less than previously thought.
But like someone said “baby steps”. Next step change it to two dimensions and then maybe 3D. There you are – plenty of future work for attracting additional grants Dr Spencer.
Jim Cripwell says:
November 11, 2013 at 2:33 pm
“… The correct conclusion to come to is that science, physics, cannot tell us what happens when you add more CO2 to the atmosphere from current levels.”
Not quite, Jim! For the last 17 years, CO2 has been added to our atmosphere, from 360 to 400 ppm. Insofar as global atmospheric temperature is concerned, the answer is quite clear, and I can tell you EXACTLY what happened: Nothing!!!
On another tack, check out the cumulative Snow Cover Extent (SCE) as well as cloud cover. For the past few years, Asia has led the record books, and snow/ice cover reflects incoming sunlight at wavelengths that CO2 does not, and cannot, re-radiate. Thus that energy is lost to the planet, and atmospheric temperatures react accordingly.
Put more floating ice into the southern ocean (2 record years in a row) and you cover absorbing water, even at shallow angles (when the Sun returns) with albedo – same result as above.
Needed: More Meteorologists and fewer climate pundits!!!
@John, Here is a good graph for you to ponder.
http://globalwarmingskeptics.info/thread-188-post-3677.html#pid3677
But models are notoriously unreliable, aren’t they?vanloonha@yahoo.com
Dr. Spencer,
You noted “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.”
Is the 9 month gestation the .pregnant pause of climate change, before the next ‘child’ is arrives?
MtK
Many thanks, S and B. This is another big step back towards sanity. Brett Keane, NZ
1.3 degrees per doubling is very close to the calculable sensitivity of 1.23 degrees.
http://climatephys.org/2012/06/28/climate-sensitivity-and-the-linearized-response/
Thanks Gary, looks like there is enough carbon dioxide up there right now to scavenge most of the available photons in the CO2 bands. I suppose a spectral analysis from space of the Earth would confirm if that is the case….
Implicit in the argument that is made by the authors of this paper is the assumption that the equilibrium climate sensitivity (TECS) is a constant. This assumption is, however, neither proved nor provable. In view of its non-provability, TECS does not exist as a scientific concept.
Dunno where the idea comes from that “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.”
They do–and other ones, too, which may or may not be seen in nature. See, for instance, this paper:
http://www.gfdl.noaa.gov/bibliography/related_files/atw0901.pdf
Roy Spencer says:
“Ulric, that’s the point of the study….to examine the cumulative effects of ENSO during the ~30 yr periods when either El Nino or La Nina are stronger.”
Your:
“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,”
seems counter-intuitive to me, as El Nino episodes discharge upper OHC and La Nina episodes recharge upper OHC. From the recharges would should see the OHC do step up changes most strongly from 1976, 1989/90 and 2001/02, i.e. following stronger/longer Nina episodes, and to lesser degree from 1986:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears_1971-2000_climo.shtml
http://www.drroyspencer.com/wp-content/uploads/APJAS-1D-model-Fig-51.jpg
And seen from a solar forcing perspective, El Nino episodes are a response to a weaker solar output, which reinforces the evidence that Nino episodes are times of net heat loss so cumulative effects would be negative. 1997/98 and 2009/10 El Nino episodes: http://snag.gy/UtqpX.jpg
mickyhcorbett75 says on November 11, 2013 at 2:01 pm:
“Roy
If we as sceptics, keep trying to model the climate and do all this other XBox type stuff then we are just as bad as the theoreticians who have a grip on the current thinking and policy.
People need to start doing some experiments.”
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Yes, mickyhcorbett75, If only – if only people would understand how. They all seem to feel it necessary to involve the ‘so called’ greenhouse gas (GHG) CO2. – However that is not necessary, at all, because the global warming theory (GWT) according to “The Kiehl & Trenberth energy budget plan 1997” (and later editions) 324 Watts per square meter (W/m²) of “Back Radiation” is being absorbed by the ‘surface’.
Well then, as you and I and indeed all (or most) human beings have a body temperature (T) of around 37º C which is well above twice that of the ‘average’ surface temperature (ST), which is said to be ± 15º C. – And, furthermore, as I do believe that as long as we have a temperature that is above that of 0 K, we all must emit IR radiation accordingly. Furthermore it is reasonable to assume that the walls that hold up the ceiling above your head are also capable of absorbing IR radiation as they (the walls) will probably be made up from some kind of “surface material”.
If you possess one of these newfangled IR – non contact – thermometers, which by the way are very accurate down to 0.1 or 0.2º C, then now is the time to use it to measure the T of any one of the four walls of your own choosing. – Is T, say between 22.4 to 22.5º C? Well, whatever it is, do invite someone else into the room, the spouse perhaps – oh you may as well invite a couple of friends and neighbors in too. – Ah, if you get too eager and invite more than just a few people, don’t forget to keep a check on the ‘T Ceiling’ (TC) as well as on ‘T Wall’ (TW) as convection from many bodies may make it warmer up there.
If you find that the walls do get warmer from “body IR radiation”, it may be necessary to do a “check experiment” against an outside wall, please let me know as it will be time for me to eat my hat.
Thank you Dr.s Spencer and Braswell for your persistence through peer review to publication of your research.