Clam fossils offer 10,000 year history of El Nino Southern Oscillation

Aug 08, 2014 by Bob Yirka report
The middens are ancient dumping sites that typically contain a mix of mollusk shells, fish and bird bones, ceramics, cloth, charcoal, maize and other plants. Credit: M. Carré / Univ. of Montpellier

(Phys.org) —A research team working in Peru, with members from France, Peru and the U.S. has found a way to track the El Niño Southern Oscillation (ENSO) going back as far as ten thousand years. In their paper published in the journal Science, the team reports that their study of clam fossils has revealed clear patterns of the ENSO and report that it has not been increasing in intensity over the course of the Holocene as some have suggested.

People have been living on the shores of the Pacific Ocean in Peru for a long time, and as they've done so, they've eaten clams, tossing the shells onto waste areas that grew to become huge mounds over thousands of years. In this new effort, the researchers dug down into several such mounds and extracted clam fossils they found, along with dirt and charcoal—remnants of ancient fires used to cook the clam meat. By taking measurements of oxygen isotopes in the , the researchers were able to calculate ocean at two to four week intervals throughout the lives of the individual clams, while radiocarbon dating of the dirt and charcoal revealed when the clams made their way into the mound. Examining multiple clams at different depths in the mounds allowed for creating a historical record of , and that allowed for charting the cycle of the ENSO going back ten thousand years.

The charts created by the research team suggest that the ENSO cycle does not have a predictable cycle and also that it has not been increasing in strength over the course of the Holocene as others have suggested. They did find some patterns, however. During a period approximately 4,000 to 5,000 years ago, for example, the ENSO was relatively weak, and during another period, from 6,700 to 7,500 years ago, ocean temperatures along the coast of Peru appeared to have been skewed by the location of from an El Niño (when trade winds push warm water into the Eastern Pacific.)

A large shell midden from the Inca period at a study site in Peru's Ica valley is shown. The climate is so dry that even wooden structures are preserved. Credit: M. Carré / Univ. of Montpellier

The findings by the team also cast doubt on some theories that have been developed to explain why the ENSO occurs at all—primary among them are those that suggest they are due to a slight wobble in the Earth's orbit. If that were the case, it would seem logical to conclude that an identifiable periodicity would emerge over the course of ten thousand years, but now, that doesn't appear to be the case.

This image shows a magnified cross-section of a shell. The lines in the outer layer come from growth during low tides, and help to put a time on the temperature measurements. Credit: M. Carré / Univ. of Montpellier


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More information: Holocene history of ENSO variance and asymmetry in the eastern tropical Pacific, Science DOI: 10.1126/science.1252220

ABSTRACT
Understanding the response of the El Niño-Southern Oscillation (ENSO) to global warming requires quantitative data on ENSO under different climate regimes. Here, we present a reconstruction of ENSO in the eastern tropical Pacific spanning the last 10 thousand years (ka) derived from oxygen isotopes in fossil mollusk shells from Peru. We find that ENSO variance was close to the modern level in the early Holocene and severely damped ~4-5 ka. In addition, ENSO variability was skewed toward cold events along coastal Peru 6.7-7.5 ka owing to a shift of warm anomalies toward the Central Pacific. The modern ENSO regime was established ~3-4.5 ka. We conclude that ENSO was sensitive to changes in climate boundary conditions during the Holocene, including, but not limited to insolation.

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User comments : 19

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Scroofinator
1.5 / 5 (11) Aug 08, 2014
The author must be lazy, or biased...
http://www.john-d...rend.htm
I have demonstrated that there is a close connection between energetic solar eruptions on the one hand and ENSO and the NAO on the other
supamark23
4.6 / 5 (13) Aug 08, 2014
The author must be lazy, or biased...
http://www.john-d...rend.htm
I have demonstrated that there is a close connection between energetic solar eruptions on the one hand and ENSO and the NAO on the other


Hmmm, peer reviewed research or some guy's blog... I'll go with the researchers diggin' through clams on this one.
Scroofinator
1.4 / 5 (11) Aug 08, 2014
Empirical data is empirical data, only a fool would think otherwise.

Obviously you can't come up with anything to challenge Landscheidt's research on your own. You keep letting that exquisite peer-review process do your thinking for you, it's clear that's all you have.
supamark23
4.6 / 5 (12) Aug 08, 2014
@scroofie - damn you're stupid.

Which data set would seem superior for determining long term variability - one spanning 10,000 years or a few spanning between 60 and 300? Again, gonna go with the clam diggers.
Scroofinator
1.4 / 5 (11) Aug 08, 2014
I'll take observed/measured data over guesstimated data any day. Funny that the observed empirical data has found a predictable cycle (that has been quite accurate) and the guesstimated data hasn't found anything.
supamark23
4.6 / 5 (9) Aug 08, 2014
What guesstimation? the techniques used are well known and valid. also, like most AGW deniers you don't understand statistics or that longer record = larger sample size = much more robust findings. It doesn't help that your link has data from before accurate measurements could have been taken of the Pacific *AND* in the future that hasn't yet happened. That's the only data set extending more than 100 years, and it's not even good data.
Shootist
1.4 / 5 (10) Aug 09, 2014
it has not been increasing in intensity over the course of the Holocene as some have suggested.



of course not, AGW is a Communist/Greenslime/demonrat myth, the only purpose of which is to control the means of production and provide a new way to take the property of one to give to another.
Da Schneib
4 / 5 (8) Aug 09, 2014
Empirical data is empirical data, only a fool would think otherwise.

Obviously you can't come up with anything to challenge Landscheidt's research on your own. You keep letting that exquisite peer-review process do your thinking for you, it's clear that's all you have.
Landscheidt was an astrologer. 'Nuff said.
Da Schneib
4 / 5 (8) Aug 09, 2014
Shootist, were you being sarcastic?
thermodynamics
4.6 / 5 (11) Aug 09, 2014
Shootist, were you being sarcastic?


No, he was being his usual incompetent self.
EnricM
4.6 / 5 (9) Aug 09, 2014


Hmmm, peer reviewed research or some guy's blog... I'll go with the researchers diggin' through clams on this one.


Yoou are an EVil minion of the IPCC and who wants to take our guns away and hide the evidence for BigFoot!!!
ItsThatGuy
4 / 5 (4) Aug 09, 2014
Course, you think bigfoot is going to come out of hiding with all these guns around? Likely to get shot.
Shootist
1.4 / 5 (11) Aug 09, 2014
Shootist, were you being sarcastic?


No, he was being his usual incompetent self.


Oh there is warming (and cooling) it just isn't being driven by humankind. AGW being the grand hubris of our age.

"the polar bears will be fine" - Freeman Dyson
Da Schneib
4.4 / 5 (13) Aug 09, 2014
So hard data on the fossil fuel burned and deforestation doesn't bother you. Got it.
howhot2
5 / 5 (7) Aug 10, 2014
Wow, this article is fantastic news. They found away to track the El Niño Southern Oscillation (ENSO) going back as far as ten thousand years! It just proves all over again that deniers are dumber than rocks.
ettubrute
5 / 5 (6) Aug 10, 2014
Anyone here that is trying to link global climate to any of the ocean oscillations is not thinking this through. The article, in no way, implies that the ENSO is directly linked to long term climate trends. The ocean oscillations, at most, alter weather patterns for different regions of the planet depending on if they are in a negative or positive phase. All of the ocean oscillations are too short in duration to be a driver of the global climate. The oscillations neither create nor destroy the heat energy of the planet. They merely help to move the heat energy around the planet from one place to another and this has regional impacts on weather patterns. None of the oscillations alter the physics concerning AGW. They do not change the Laws of Thermodynamics. They do not alter the Laws of Chemistry. The AGWT does not violate any of The Laws of Physics, Thermodynamics or Chemistry.
howhot2
5 / 5 (6) Aug 11, 2014
@ettubrute; You are right of course. The only thing you might want to consider is the influence on the strength of the ENSO with the added temperatures from AGW. It will be interesting to see how future modeling is effected by the new data.
Personally I obey the Laws.
ettubrute
5 / 5 (5) Aug 11, 2014
howhot2, I agree that the planet will likely see another sharp rise in global temperatures when the next strong and extended El Nino comes into play. Just as we saw a sharp rise in global temperatures with the strong and extended 1998 El Nino event. Those that will not display any ability to use critical thinking will likely just say that it is warmer because of the El Nino event and fail to see the stair stepping in global temperatures as the El Nino returns to a neutral to negative phase. The global temperatures do not drop back to the temperatures before the El Nino event and will plateau at a higher temperature than before. This will be due to the greenhouse effect keeping some of the heat energy being released from returning back to space. We already know what the denial sphere will be saying. They will use the next sharp rise in global temperatures as a starting point to say, "See, it hasn't warmed in the last ten years!". Yes, the warming will continue even after the event.
Da Schneib
5 / 5 (3) Aug 16, 2014
The ocean oscillations, at most, alter weather patterns for different regions of the planet depending on if they are in a negative or positive phase. All of the ocean oscillations are too short in duration to be a driver of the global climate. The oscillations neither create nor destroy the heat energy of the planet. They merely help to move the heat energy around the planet from one place to another and this has regional impacts on weather patterns. None of the oscillations alter the physics concerning AGW. They do not change the Laws of Thermodynamics. They do not alter the Laws of Chemistry. The AGWT does not violate any of The Laws of Physics, Thermodynamics or Chemistry.
You can think of these oscillations as the bubbles in a boiling pot of water; they just transfer heat around, they don't turn the water into not-water.

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