Ancient shellfish remains rewrite 10,000-year history of El Niño cycles
Hannah Hickey University of Washington
The planet’s largest and most powerful driver of climate changes from one year to the next, the El Niño Southern Oscillation in the tropical Pacific Ocean, was widely thought to have been weaker in ancient times because of a different configuration of the Earth’s orbit. But scientists analyzing 25-foot piles of ancient shells have found that the El Niños 10,000 years ago were as strong and frequent as the ones we experience today.
The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.
“We thought we understood what influences the El Niño mode of climate variation, and we’ve been able to show that we actually don’t understand it very well,” said Julian Sachs, a UW professor of oceanography.
The ancient shellfish feasts also upend a widely held interpretation of past climate.
“Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then,” said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.
In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.
While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.
The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.
The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.
One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth’s orbit around the sun during that period.
“The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents,” Carré said.
Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth’s orbital geometry might have taken over then to cause the period of weak El Niños.
In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.
The new data is more reliable, Carré said, for three reasons: the Peruvian coast is strongly affected by El Niño; the shells record ocean temperature, which is the most important parameter for the El Niño cycles; and the ability to record seasonal changes, the timescale at which El Niño can be observed.
“Climate models and a variety of datasets had concluded that El Niños were essentially nonexistent, did not occur, before 6,000 to 8,000 years ago,” Sachs said. “Our results very clearly show that this is not the case, and suggest that current understanding of the El Niño system is incomplete.”
The research was funded by the U.S. National Science Foundation, the U.S. National Oceanic and Atmospheric Administration and the French National Research Agency.
Other co-authors are Sara Purca at the Marine Institute of Peru; Andrew Schauer, a UW research scientist in Earth and space sciences; Pascale Braconnot at France’s Climate and Environment Sciences Laboratory; Rommel Angeles Falcón at Peru’s Minister of Culture; and Michèle Julien and Danièle Lavallée at France’s René Ginouvès Institute for Archaeology and Anthropology.
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It’s all settled. It’s CO2, that’s it.
The Ministry of Truth has said so, therefore, it is true.
Slowly but surely the truth is coming out about how untrustworthy the computer models used by climate scientist are, compared to real empirical data. CO2 alarmist’s are losing their minds over this & I take great enjoyment in watching them try to explain their point of view.
“Climate models and a variety of datasets had concluded that El Niños were essentially nonexistent, did not occur, before 6,000 to 8,000 years ago,” Sachs said. “Our results very clearly show that this is not the case, and suggest that current understanding of the El Niño system is incomplete.”
I just love real science.
First line in the abstract: “Understanding the response of the El Niño-Southern Oscillation (ENSO) to global warming requires quantitative data on ENSO under different climate regimes” They just had to say it. It’s probably a requirement to frame things relative to global warming to get published….
I appreciate their hard work but nobody has ever had a clue about what causes changes in ENSO.
Every prediction of it they make more than 3 months out fails miserably yet they’re surprised computer models don’t know what it was like 10,000 years ago?
How can there be global “climate changes” from one year to the next? Weather, yes. Climate, no. Even one decade to the next isn’t climate.
The requirements for an ENSO are a wide deep ocean at the equator, a rotating Earth, and Trade Winds. That makes for an ENSO operating for about 80% of Earth history.
Well clearly the shells will have to be sent to a re-education camp and forced to take earth sciences classes.
The more climate history I learn, the more interesting and complex the picture gets.
And those I argue with haven’t got so much as the Faintest clue…
Bill Illis says:
August 8, 2014 at 4:31 pm
You’re right.
I wonder just who imagined that El Ninos didn’t occur six to eight thousand years ago.
Even “climate scientists” (TM) have debated whether they were continuous or not during the Pliocene, when it was warmer and the Isthmus of Panama was a strait.
Are all these new studies coming out because a new generation has taken over and the corrupt ones like Hansen, Mann, Briffa, Jones are aging towards retirement? Will history look back and show that 25 year span starting in 1988 for what it was ‘A time when a group of scientists led by Hansen and Mann decided to distort and adjust facts to meet a political agenda’. Are hurricanes up? Are tornadoes up? Mosher and Stokes know deep down that CAGW is a myth and the slight warming we have gotten is mostly beneficial.
For example, even during glaciations (note lead author):
http://www.nature.com/nature/journal/v428/n6980/abs/nature02386.html
Nature 428, 306-310 (18 March 2004) | doi:10.1038/nature02386; Received 29 July 2003; Accepted 3 February 2004
Millennial and orbital variations of El Niño/Southern Oscillation and high-latitude climate in the last glacial period
Chris S. M. Turney1,7, A. Peter Kershaw2, Steven C. Clemens3, Nick Branch4, Patrick T. Moss5 & L. Keith Fifield6
The El Niño/Southern Oscillation (ENSO) phenomenon is believed to have operated continuously over the last glacial–interglacial cycle1. ENSO variability has been suggested to be linked to millennial-scale oscillations in North Atlantic climate during that time2, 3, but the proposals disagree on whether increased frequency of El Niño events, the warm phase of ENSO, was linked to North Atlantic warm or cold periods. Here we present a high-resolution record of surface moisture, based on the degree of peat humification and the ratio of sedges to grass, from northern Queensland, Australia, covering the past 45,000 yr. We observe millennial-scale dry periods, indicating periods of frequent El Niño events (summer precipitation declines in El Niño years in northeastern Australia). We find that these dry periods are correlated to the Dansgaard–Oeschger events—millennial-scale warm events in the North Atlantic climate record—although no direct atmospheric connection from the North Atlantic to our site can be invoked. Additionally, we find climatic cycles at a semiprecessional timescale (approx11,900 yr). We suggest that climate variations in the tropical Pacific Ocean on millennial as well as orbital timescales, which determined precipitation in northeastern Australia, also exerted an influence on North Atlantic climate through atmospheric and oceanic teleconnections.
It’s not just 10,000 years ago.
Notice they say models and data sets suggested El nino
Were non existent.
Models and data agreed.
Now there is more data.
Shells.
Cagw isn’t even defined.
Agw yes.
Steven Mosher says:
August 8, 2014 at 5:32 pm
What data sets suggested no El Ninos?
And since when did models need data, when it’s so much more fun and easier just to make stuff up?
Steven Mosher says:
August 8, 2014 at 5:39 pm
Supposed catastrophes are indeed vague. So far more CO2 has been a good thing.
Is AGW defined? If so, how is it measured? What evidence is there of any statistically significant AGW at all since 1700, 1850, 1900, 1950, 1975, whenever?
“Notice they say models and data sets suggested El nino
Were non existent.
Models and data agreed.
Now there is more data.
Shells.”
– Needs a fair bit of work before it is Haiku.
Mosh,
CAGW is clearly understood. AGW is warming of 0 degrees to 1.99 C. CAGW is 2.0 or higher. Life on earth will end if the temp. goes up 2C. Ebola most likely will kill all the humans before the plankton dying kills the rest of life on earth.
[It is very telling of today’s headlines, and today’s CAGW supporters, that we do not know (and cannot tell) if this paragraph needs a “/sarcasm” tag added. .mod]
Bill_W says:
August 8, 2014 at 6:00 pm
It’s worse than we thought! Earth is on the Venus Express, and we’re to blame! We’re all going to die by drowning and then burn up!
CAGW = Catastrophic Anthropogenic Global Warming.
That’s the definition.
So does that mean that the different orbital parameters actually had little or no effect on the insolation and thus ENSO?
“ Steven Mosher says:
August 8, 2014 at 5:39 pm
Cagw isn’t even defined.
Agw yes.”
If it’s not catastrophic then who gives a toss? The EU supposes to reduce CO2e emissions 80% by 2030 compared to 1990. That would be a catastrophe – considering agriculture alone makes up most of the remaining 20%.
If it’s just AGW and not CatastrophicAGW then a whole lot of feeble-minded “scientists” are on the dole.
A nice piece of science, putting together two separately recognized established methods (radiocarbon dating from archeology and delta O13 from climatology ice cores and ocean proxies) to actually go analyze real middens (which exist, cause he has pictures) and can be resampled for reproducibility (which he already did, and anyone else could). Low and behold, ENSO is not new news. The only stunning part is that warmunists supposed it might have been in order to perpetuate their hockey stick world view.
Well, upon further reflection, how could anyone be stunned by anything that warmunists have ever espoused, since it is almost all beyond silly? As proven yet again here.
Maybe Gaia has a thermostat that compensates (!?).