El Nino is becoming more active

Oct 28, 2013
Corals, tree rings, and sediment cores serve as proxies for El Niño sea surface temperature. Credit: Gisela Speidel

A new approach to analyzing paleo-climate reconstructions of the El Niño Southern Oscillation (ENSO) phenomenon resolves disagreements and reveals that ENSO activity during the 20th century has been unusually high compared to the past 600 years. The results are published in Climate of the Past by a team of scientists from the University of New South Wales, the University of Hawaii International Pacific Research Center and the NOAA Geophysical Fluid Dynamics Laboratory.

El Niño events can wreak havoc across the globe, spawning floods or giving rise to droughts in many regions of the world. How ENSO behaves as a result of a warming planet, however, is still uncertain. One window to determine its sensitivity to change is a look into the past. Because the instrumental record is too short for getting a reliable picture of natural variations in ENSO magnitude and frequency, climate scientists rely on geological and biological clues, such as from lake sediment cores, corals, or tree rings as proxies for past ENSO behavior. The problem has been, though, that reconstructions of ENSO from such paleo-proxies have not been telling the same story.

Some of these discrepancies in ENSO reconstructions arise because the methods typically applied to combine individual paleo-proxy records do not handle small dating uncertainties amongst the proxies well. The usual approach has been to combine the individual ENSO proxies and then to calculate the activity of this combined ENSO signal. McGregor and his team found that by turning this analysis around—first calculating the activity of ENSO in each of the individual paleo-climate reconstructions and then combining the activity time series—yields a much more consistent and robust view of ENSO's past activity. The scientists confirmed this new approach with virtual ENSO data obtained from two multi-century-long climate model simulations.

Applying their improved method of reconstructing ENSO activity by synthesizing many different existing proxies and comparing these time series with instrumental data, the scientists found that ENSO was more active during 1979-2009 than during any 30-year period between 1590 and 1880.

"Our results represent a significant step towards understanding where current ENSO activity sits in the context of the past." says Axel Timmermann, professor at the University of Hawaii and co-author of the study.

"Climate models provide no clear indication of how ENSO activity will change in the future in response to greenhouse warming, so all we have to go on is past records," explains McGregor. "We can improve the projections of , however, by selecting those that produce past changes in ENSO activity consistent with the past instrumental records.

"Our new estimates of ENSO activity of the past 600 years appear to roughly track global mean temperature," says McGregor, "but we still don't know why."

Explore further: NASA's HS3 mission continues with flights over Hurricane Gonzalo

More information: S. McGregor, A. Timmermann, M. H. England, O. Elison Timm, and A. T. Wittenberg: Inferred changes in El Niño–Southern Oscillation variance over the past six centuries. Clim. Past, 9, 2269, 2013. DOI: 10.5194/cp-9-2269-2013

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discouragedinMI
1.7 / 5 (19) Oct 28, 2013
"Our new estimates of ENSO activity of the past 600 years appear to roughly track global mean temperature," says McGregor, "but we still don't know why."

Ummm, I'm only a lowly Physicists at a small university in the US but I think they answered their own question. If the ENSO activity is roughly tracking with the mean global temperature the simplest answer is that the oceans drive surface temperatures and not the reverse. Perhaps GHG forcing isn't as large as the climate models are assuming.

cantdrive85
1.6 / 5 (19) Oct 28, 2013
"Our new estimates of ENSO activity of the past 600 years appear to roughly track global mean temperature," says McGregor, "but we still don't know why."

Ummm, I'm only a lowly Physicists at a small university in the US but I think they answered their own question. If the ENSO activity is roughly tracking with the mean global temperature the simplest answer is that the oceans drive surface temperatures and not the reverse. Perhaps GHG forcing isn't as large as the climate models are assuming.


Hurray! Logic presented even by small lowly American physicists.
runrig
3.5 / 5 (8) Oct 28, 2013
mmm, I'm only a lowly Physicists at a small university in the US but I think they answered their own question. If the ENSO activity is roughly tracking with the mean global temperature the simplest answer is that the oceans drive surface temperatures and not the reverse. Perhaps GHG forcing isn't as large as the climate models are assuming.


No - solar energy drives sea temperature including that re-radiated back from GHG's. Then yes, heat is transferred to the atmosphere. But recently more heat has been accumulating in the sea than has been getting out. You still cannot get away from the fact that ultimately the Earth's heat comes from the Sun and we know that is not the cause of warming. Yes we do.
goracle
2.3 / 5 (16) Oct 28, 2013
"Our new estimates of ENSO activity of the past 600 years appear to roughly track global mean temperature," says McGregor, "but we still don't know why."

Ummm, I'm only a lowly Physicists at a small university in the US but I think they answered their own question. If the ENSO activity is roughly tracking with the mean global temperature the simplest answer is that the oceans drive surface temperatures and not the reverse. Perhaps GHG forcing isn't as large as the climate models are assuming.


Hurray! Logic presented even by small lowly American physicists.

Perhaps next year you won't miss the lecture about the difference between logic and what you want to hear.
discouragedinMI
1.2 / 5 (17) Oct 28, 2013
Check the global mean temperatures, sea surface temperature anomalies, and the satellite temperature data. They all correlate very nicely (with bumps, of course) to the ENSO index however they don't correlate to the climate models. And don't use that data that has been massaged with clever schemes. I'm sorry but given the level of confidence that even the IPCC is putting in the climate models, I have to fall back on Occam's Razor. The hypothesis with the simplest answer is generally closest to the truth. Further complications should be added only when they add explanatory power. Since day 1 the IPCC has assumed that natural variability is minimal, however recent studies have shown this not to be true. In their own AR5, they admit to this and even point to a need for more research in this area. However, the IPCC and many climate scientists have failed to accept the one simplest possibility. Their climate models use too high of a sensitivity to the CO2 feedback mechanism.
Humpty
1 / 5 (15) Oct 29, 2013
Hmmmmm the first mistake in this report is failing to follow the official doctrine that most of the world does not speak Spanich, and the real terms actually link directly to the effect.

Namely

We have the El Dryo and the El Wetto effects.

El Nino and El Ninia have been banned from all nonclemeture,
DirtySquirties
2.7 / 5 (12) Oct 29, 2013
@Humpy - What is "nonclemeture"? I assume "Dryo", "Wetto", and "Ninia" are made up words, so is this made up as well? Are you speaking "Spanich"?
runrig
5 / 5 (5) Oct 29, 2013
Since day 1 the IPCC has assumed that natural variability is minimal


No, they have assumed that natural variability is cyclic. Up down. And they play themselves out with a period of around 30 years. Hence why the current slowing is no surprise. And why it was not (specifically) modeled as the ENSO cycle is of variable length. These natural cycles are AVERAGED out in the models.