No 'permanent El Nino,' scientists say—and the tropics may get even hotter

Apr 04, 2014 by Eric Gershon
No 'permanent El Nino,' scientists say—and the tropics may get even hotter
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(Phys.org) —New research by Yale University scientists challenges a long-standing paradigm for temperature variability in the Pacific Ocean, casting doubt on the existence of a past period of "permanent" El Niño-like conditions and suggesting that the tropics could grow markedly hotter.

"There's good news and bad news about future ," said Mark Pagani, professor of geology and geophysics at Yale and an author of the research, published April 4 in the journal Science.

"The good news is that global warming does not drive the Pacific Ocean into a permanent El Niño-like condition with all the other regional climate impacts that come with that. The bad news is that the tropics will warm as we continue to add greenhouse gases to the atmosphere—and the recent past was probably much warmer than generally assumed."

Modern El Niño conditions are characterized by unusually warm surface water in the eastern equatorial Pacific, and a very low overall equatorial Pacific gradient. The quasi-periodic phenomenon's effects on global weather patterns can be dramatic, including extreme rainfall in some places (Texas, for example) and drought elsewhere (Indonesia and Australia).

A conventional view holds that in the warmest part of the equatorial Pacific—the vast western "warm pool"—remained relatively constant for millions of years. Given that ocean temperatures elsewhere rose during this time, the warm pool's stable temperature implied a tropical ocean "thermostat" or temperature control mechanism, Pagani said.

But in a new reconstruction of ancient Pacific sea surface temperatures covering 12 million years, Pagani and Yale doctoral candidate Yi Ge Zhang found that Pacific warm pool temperatures were notably higher 12 million years ago than previously thought—as much as 4°C warmer. Their results indicate that all parts of the Pacific warmed during past periods of global warming, suggesting greater variability of ancient ocean temperatures and the absence of any tropical temperature control mechanism or "permanent El Niño-like" conditions.

"El Niño conditions today are characterized by very low equatorial Pacific temperature gradients," Pagani said. "It seemed from previous data that the equatorial Pacific maintained similarly low temperature gradients in the past and thus reflected a 'permanent' state characteristic of the modern El Niño. Our work dispels this idea by showing that the processes responsible for today's strong equatorial temperature gradient, with a western warm pool and the eastern cold tongue, were also operating in the past. There is no evidence of a tropical thermostat that keeps the tropics from overheating."

He added, "Building a better understanding of the world and clarifying the nature of a warmer Earth helps us better prepare for the inevitable impact of our behavior."

The revised ancient temperatures are based on analysis of biomarkers.

The paper is titled "A 12-million year temperature history of the tropical Pacific Ocean."

Explore further: Researchers suggest controversial approach to forecasting El Nino

More information: Paper: "Not So Permanent El Niño", Science, 2014.

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Shootist
1 / 5 (7) Apr 04, 2014
No 'permanent El Nino,' scientists say—and the tropics may get even hotter


Or not.

"Generally speaking, I'm much more of a conformist, but it happens I have strong views about climate because I think the majority is badly wrong, and you have to make sure if the majority is saying something that they're not talking nonsense." - Freeman Dyson

As a general rule, if Freeman Dyson doesn't understand something, neither do you. And yes, Michael Mann, James Hansen and Eric Gershon, I am talking to you.
Maggnus
5 / 5 (6) Apr 05, 2014
"What I'm convinced of is that we don't understand climate, and so that's sort of a neutral position. I'm not saying the majority is necessarily wrong. I'm saying that they don't understand what they're seeing. It will take a lot of very hard work before that question is settled, so I shall remain neutral until something very different happens."

In other words, he hasn't really looked at the issue, but distrusts "the majority opinion"; this is a position he has taken for most of his life on everything from Relativity to PH.D education. If you think he is so smart Shootist, you aught to try and understand what he is actually saying, rather than taking up the sound bites handed to you by denialist blog writers.
Tim Thompson
5 / 5 (6) Apr 05, 2014
As a general rule, if Freeman Dyson doesn't understand something, neither do you

As a general rule, that is generally wrong. While Dyson is no doubt brilliant, that should not & does not mean that he is better at understanding any technical field to the same extent that any active journeyman professional in the field understands it, even if Dyson thinks otherwise. Dyson says, "I was involved in climate studies seriously about 30 years ago." … "I don't claim to be an expert. I never did." … "And, secondly, I am not an expert, and that's not going to change. I am not going to make myself an expert." I will trust an expert in climatology before I trust Dyson.
http://e360.yale....?id=2151

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