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.
A major step in the right direction.
Roy, how did your model account for the other major mode of natural variability, the AMO?
Reblogged this on Bob Tisdale – Climate Observations and commented:
A giant step in the right direction.
Bob beat me to it!
But this NOAA graphic shows the influence the AMO has on NH temperatures.
http://www.aoml.noaa.gov/phod/faq/faq_fig2.php
I suppose CO2 has to be thrown into the study in order to get it published, or, am I getting too cynical?
That is so correct, if one plots El Nino events versus La Nina events versus temperature changes one will find a rather strong correlation.
ENSO, is a major factor for temperature change when the climate is in a particular climatic regime, but in order to have a more dramatic sustained change one has to look to the sun.
I have stated the solar average parameters that are needed many times in order to achieve this result.
Certainly, we have a lot more to understand in the study of natural climate variability, and it would be easy to get into quantitative and chicken/egg arguments over over ENSO cycles vs. PDO and AMO and cosmic rays and so on. But the important question here is whether or not we wholeheartedly acknowledge that this work is far superior to the IPCC conclusions that CO2 is the primary driver of climate change and that humans are to blame.
If you agree that this paper represents a far superior understanding of climate variability than what the IPCC is selling, state that first before diving into the minutia. Please, don’t throw the baby out with the bath water.
Cmon, another case of discovering what is a known, that warm pdo.s have more el ninos and so there is global warming. Joe D Aleo has shown that the average warm PDO el nino is longer and stronger, the opposite in the cold pdo where el ninos average only 9 months and la ninas 21 months. Since el ninos spike the global temps, more el ninos mean cumulative warming
cold pdos mean temps start down, as we have seen the past 4 years, The leveling years are the atmosphere reaching a balance from the added heat from this. Its like turning on a hot shower, the bathroom warms until it can warm no more. Shut the shower off, the bathroom cools
How is this some brilliant finding
Its amazing watching knowns, things observed years ago being funded and now somehow coming to light as a brilliant discovery. This is a known among nuts and bolts forecasters that have worked in this field for years.
Simply amazing
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.
This is the way to model climate – base the modeling directly on experimental data (here satellite data). Yes – clouds CAN be included in climate modeling. But the results shown here – halving of CO2 sensitivity – show why the establishment have resisted so hard including clouds.
Meanwhile the warmist establishment spout nonsense about aerosol cans and CFCs and ignore clouds completely.
Old news.
The bit that would be more interesting would be to confirm why there are upward temperature steps from one positive phase to the next during a warming spell such as LIA to date and probably downward steps from one negative phase to the next during a cooling spell such as MWP to LIA.
I have proposed that the cause is solar variability affecting global cloudiness which skews ENsO towards El Nino when the sun is becoming more active and towards La Nina when the sun is becoming less active.
But, that can’t be true. If it is then, in order for National Geographic’s proposed rise of 22F will require us to double the current CO2 level approx 17x to …. well a REALLY high % of atmospheric content (something approaching 100% I believe). So, it can’t be true
We been sayin. This whole time we’all been sayin. With our snaggle tooth grin and flat Earth think’n, we all been sayin. My ol’ kin in Ireland say it. My great-great-great grandpa say it. My great-great grandpa say it. My great-grandpa say it. My grandpa say it. And my pa say it. And all the women folk been sayin it longer than that. Since a’fore the American Revolution the weather she come an she go, sometime a’blowin at our back and sometime a’blowin up our kilt. We all known it cuz we cross the ocean more’n once on nut’n but a rickety boat. Yet these here whipper snappers think they be sayin it for the fust time.
Lord A’mighty!
Wake me up when you have shown your model has made a real prediction, within narrow useful boundaries, that future data collection confirms. Doing it twice would be even more impressive.
Half is slight!? It is these ‘slight’ amounts that are fueling the debate.
models all the way down
C’mon Joe, we’re on the same side, dude. 😉
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. Without that, El Nino warmth would just be a near-surface phenomenon (because it coincides with approximately equal cooling in the 100-200 m layer), and incapable of explaining the increase in ocean heat content.
We also quantify how much it reduces diagnosed climate sensitivity by. This goes far beyond just handwaving that “stronger El Ninos cause warming”.
AND to get it published is no small task, given today’s peer review bias.
Jimbo says:
November 11, 2013 at 10:06 am
The “slightly” refers to the reduction in CS from ocean mixing alone. They found reduction by half when clouds were added in. This confirms what so many have long suspected, ie that IPeCaC leaves clouds out of its GIGO model because they knew what the result would be if included. Their lame excuses for not including clouds have never held water, so to speak, or were vaporous.
I’m with Joe Bastardi and Jimbo on this – and not only unremarkable, but an apparent concession to some of the false claims of CO2 sensitivity put forth by the alarmists. Yeah, temps are sensitive to CO2 – but in reality, it’s too small to quantify accurately or attribute correctly. It seems pointless to discuss the sensitivity in this context, and it gives the alarmists an opening to say “See? We told you so! Climate is still very sensitive to CO2 even in your scenario, and you admit it!”
I remain convnced that we skeptics need to maintain a hard line and not give ground to alarmists. Their meme is so wrong and so thoroughly discredited that I see no reason to make any sort of concession to them. If we are wrong on this, our error will be minuscule compared to the alarmists’.
Time to show the trend changes since 1850:
http://woodfortrees.org/plot/hadcrut4gl/from:1850/to/plot/hadcrut4gl/from:1880/to:1912/trend/plot/hadcrut4gl/from:1912/to:1944/trend/plot/hadcrut4gl/from:1944/to:1976/trend/plot/hadcrut4gl/from:1976/to:2005/trend/plot/hadcrut4gl/from:2005/to/trend/plot/hadcrut4gl/from:1850/to:1880/trend
Yup, as many of us have been saying for years, the climate is driven by the oceans. I commend Dr. Roy for getting this knowledge into the peer reviewed literature. While I think the sensitivity is still a bit high it is low enough to end the alarmism and that is more important than getting a perfect answer. From where we are at it will take around 200 years to double CO2 again and with only a 1.3C temperature rise we are less than the 2.2 C of net beneficial warming found by Dr. Richard Tol.
Congratulations Roy and Dan, great work. Now prepare yourself for the coming ad hominem attacks.
Any mention of the theory advanced here recently that the clean air act cleared the smog
aerosols away and led to sudden spurt of warming after 1980?
Roy Spencer said:
“there is more radiant energy coming in during El Nino, about 0.6 W/m2 per unit MEI Index value. Without that, El Nino warmth would just be a near-surface phenomenon (because it coincides with approximately equal cooling in the 100-200 m layer), and incapable of explaining the increase in ocean heat content. ”
Exactly, which is why one needs the cloud reduction first.
That is what led to my emphasis on a top down solar effect to kick start the cloudiness changes as per my New Climate Model which is just a summary of observed events in the correct sequence.
True, the El Nino once in progress will add energy to the air above and in doing so widen the equatorial air masses but one has to stoke up the energy for a strong El Nino in the first place and replace the lost energy when it occurs.
During the late 20th century warming spell more energy was entering the oceans than leaving them despite a string of powerful El Ninos.
Now, less energy is entering the oceans than leaving them despite ENSO neutral conditions.
The current recharge rate is much reduced by increased global cloudiness so the skids are being put under the prospects of strong future El Ninos. If we do get a strong El Nino despite the current low recharge rates the subsequent cooling will be undeniable.
Hope I’m still alive when someone in authority ‘gets’ it.
The general result of this study is perfectly consistent with other studies recently published (Curry’s work, Chylek’s work and my own works) showing that natural cyclical variability would account for 50% of the warming during the last decades. Therefore the climate sensitivity to CO2 needs to be reduced by about half.
What remains unexplained is the physical origin of this natural variability. In fact, here ENSO is used as an input of the climate model, not as the output (as it should be). In fact, Spencer and others are “assuming” that this is just an internal unforced variability of the climate system that exists by itself. However the fact remains that the observed natural climatic oscillations are synchronous to evident astronomical cycles of lunar/solar/planetary origin.
Thus, the observed natural variability is likely astronomically induced, as explained in my papers.
For more details see
Scafetta, N. 2013. Discussion on climate oscillations: CMIP5 general circulation models versus a semi-empirical harmonic model based on astronomical cycles. Earth-Science Reviews 126, 321-357.
http://www.sciencedirect.com/science/article/pii/S0012825213001402
or my website.
Stephen, your downfall is failing to take the next step beyond your “belief”: proving your “belief” wrong. You dismiss neutral (as others have so don’t feel too bad) as if nothing is going on that neutral conditions have an affect on. However I think ENSO neutral is the new scientific frontier in climate investigation. We should be delving into this span of data as diligently as we have La Nina and El Nino because neutral incorporates such a large area on Earth and a great deal of data, maybe even more than the two extremes combined. Long live El Nado and La Nada. Possibly the elephant in the room.
“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.”
Is that for every doubling: 50 ppm to 100 ppm, 100 ppm to 200 ppm, 200 ppm to 400, etc. or just to the most current move toward doubling from 250 ppm to about 400 ppm now as it rises?
Is there a recognized saturation point where additional CO2 makes absolutely no difference?
This seems to be conflating the immediate with the cumulative effects of ENSO. For the cumulative effects, multi-year or stronger La Nina episodes should be causing and preceding the up steps in global temperature.
The usual attack will now commence. The pro-warmers cannot settle for a climate sensitivity value that is so low and so benign if not beneficial.