Warming since 1950s partly caused by El Nino

Nov 14, 2013
Dr. Roy Spencer’s models show that a natural shift to stronger warm El Niño events might be responsible for a substantial portion of global warming during the past 50 years. Credit: UAH

(Phys.org) —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 cycles explain at least part of the 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 10 or 15 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 the deep ocean on multi-decadal time scales.

"As a result, because as much as 50 percent 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 , 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 the interpretation of how sensitive the climate system is to CO2 emissions.

Explore further: Researchers construct a model of impact for El Nino / La Nina events

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User comments : 18

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omatwankr
2.4 / 5 (26) Nov 14, 2013
"I finally became convinced that the theory of creation actually had a much better scientific basis than the theory of evolution," The Evolution Crisis by Dr. Roy Spence
Grallen
2.9 / 5 (17) Nov 14, 2013
@ omatwankr: Thank you for pointing out this information is coming from a madman.
jscroft
2 / 5 (25) Nov 14, 2013
Yup: impugn the messenger and change the subject. That's what true-believing morons do when they can't refute an argument.
orti
1.7 / 5 (18) Nov 14, 2013
A hearing for a denier on extreme advocacy site phys.org? Heads will roll for this.
orti
1.5 / 5 (17) Nov 14, 2013
"The Evolution Crisis by Dr. Roy Spence"
Almost. Actually its Testing Truth with an Open Mind, Dr. Roy Spencer. You can read the whole thing at http://theevoluti...ny2.php. You might enjoy it – if you dare.
Grallen
3 / 5 (6) Nov 14, 2013
Um... he's not a denier. Read the article closer.

Do you just read the title, scroll past the article to the comments, and try to guess at the article's contents?
cantdrive85
1.6 / 5 (21) Nov 14, 2013
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.

Yet, this "science" is "settled" according to many... Rubes!
orti
1.9 / 5 (16) Nov 14, 2013
Grallen,
True. But like James Lovelock (gaia hypothesis) and others he refutes the alarmists.
Grallen
3.7 / 5 (9) Nov 14, 2013
Or... He thinks he's come up with a way to improve the models.

He also thinks he's come up with "the explanation" for "the pause".

He also suggest that the world might take longer to warm up than expected. Which is an optimists perspective, not a denier perspective.

So, as pointed out, his statements should be taken with a grain of salt, considering his history.

Or for the lazy reader, wait for follow up article to happen about a more reputable researcher checking his results.
orti
1.7 / 5 (18) Nov 14, 2013
Grallen,
Is anyone who disagrees a "madman" or someone with a faulty mind or dishonest or lazy? The guy has satellite evidence that more energy is leaving the earth than the alarmist models predict.
The Alchemist
1.6 / 5 (19) Nov 14, 2013
Conservation of energy would tend to disagree.
The currents are responsive not drivers. If effects did not occur because of ElNino, then they would have had to find another way to occur.
Of course they are still muddying the waters with CO2, when if we use the driest desert as a baseline and the normalized absorption spectrum of CO2 and H2O, we see that a modest estimation makes water at least 72 times more powerful Green House gas.
Then we should consider water's heat transport capability. Higher heat capacity as ice and water, enthalpy of formation (water --> ice releases collosal amount of heat, water --> vapor absorbes collossal amounts of heat) etc.. Then we consider the driest desert is hardly the norm, that would be something like, oh say, THE ATLANTIC and PACIFIC OCEANS.
FrankTrades
1.6 / 5 (21) Nov 14, 2013
Relative to destruction of the climate, this scientist has posted this comment numerous times on other sites and has yet to receive any salient feedback:
See the chart here:

http://tidesandcu...=8518750

Do you see any influence of man in this trend of sea level increase? If you do, you are a better scientist than I am. With the increase in population from the mid-1800s to now and with the increase in burning of hydrocarbons during that time period, if there were man-made influence, it would surely show up here. I believe US population alone has increased 10 times since the initial date on that chart. If there were anthropomorphic influence on earth temperatures, it would show up here and it DOES NOT.

All the hockey sticks in NY are at Madison Sq. Garden. And speaking of ice, the location of MSG was covered by 5000 feet of glacial ice. Of course climate is warming -- it has been warming for thousands of years.
runrig
4.2 / 5 (10) Nov 14, 2013
………….. If there were anthropomorphic influence on earth temperatures, it would show up here and it DOES NOT.


I wouldn't expect it to – it is merely one site on Earth, not an overall picture.

"The rate of sea-level rise as measured both by the satellite altimeter record and the in situ reconstruction of about 3 mm year−1 since 1993 is near the upper end of the sea-level projections for both the Intergovernmental Panel on Climate Change's Third (Church et al. 2001) and Fourth (Meehl et al. 2007—see also Hunter 2010) Assessment Reports."

http://link.sprin...ext.html

"This data has shown a more-or-less steady increase in Global Mean Sea Level (GMSL) of around 3.2 ± 0.4 mm/year over that period. This is more than 50% larger than the average value over the 20th century. Whether or not this represents a further increase in the rate of sea level rise is not yet certain."

http://www.cmar.c..._15.html
Egleton
2.8 / 5 (16) Nov 14, 2013
I am amazed that anybody can finesse their models down to 1.3C when they are dealing with positive feedback loops.
NikFromNYC
1.3 / 5 (16) Nov 15, 2013
Roy runs one of the intensely peer reviewed global average temperature data sets, based on satellites.

Yes, I plugged this paper, here.

Thanks, Phys.org.
verkle
1 / 5 (14) Nov 15, 2013
orti---I don't remember seeing your comments before today, but I like them! Welcome to phys.org!
thermodynamics
3 / 5 (4) Nov 15, 2013
Roy runs one of the intensely peer reviewed global average temperature data sets, based on satellites.

Yes, I plugged this paper, here.

Thanks, Phys.org.


Nik: You have never had anything other than disparagement for any models. Does it just take a model that agrees with your world view to change your mind?

Don't get me wrong. I am an advocate of models and I would like to see this model validated. However, at this point I don't have any reason to "believe" any one model over any other. Instead, I like to see ensembles of models to look at how they agree and how they disagree then determine which is better at representing reality at a fundamental level.

You have said that all models are useless. Does this model change your mind?

Do you now believe that this model is useful?

What is your criteria for discounting all models then deciding that one finally works?
Bob_Wallace
1.7 / 5 (12) Nov 16, 2013
Roy isn't a climate change denier. He accepts the fact that the planet is warming.

He works very hard to be a 'GHG increases are causing climate change' denier.

He does run an intensely peer reviewed global temperature data set, based on satellites. It is necessary for other climate scientists to intensely review what he reports about the data because he makes "mistakes" in his interpenetration of the data.

Roy has a poor reputation in his field. A reputation which he has earned.