From the AGU Weekly highlights:
El Niño–Southern Oscillation variability persisted in warmer world
Changes in the distribution of sea surface temperature associated with the El Niño–Southern Oscillation (ENSO) cause significant changes in weather. In the past 40 years it has been observed that the frequency and intensity of El Niño events have been increasing. Scientists would like to know what will happen to ENSO variability as the world’s climate warms.
To find out, some have looked to the mid-Piacenzian Warm Period (mPWP), a period about 3.26 to 3.03 million years ago that was about 3° Celsius (5.4° Fahrenheit) warmer than present day and that may be analogous to what can be expected in the future if climate continues to warm. Some studies have suggested that during the mPWP, there was actually no ENSO variability but rather a permanent El Niño state.
To learn more about ENSO variability during the mPWP, Scroxton et al. analyze the isotopic composition of planktonic foraminifera from the eastern equatorial Pacific, as well as ENSO simulations conducted with a coupled ocean atmosphere climate model. Their proxy and model data suggest that interannual ENSO variability did persist during the mPWP, with a mean state similar to a modern El Niño event. Furthermore, they found that during the mPWP, ENSO events may have been more regular and more intense.
Source: Paleoceanography, doi:10.1029/2010PA002097, 2011
http://dx.doi.org/10.1029/2010PA002097
Title: Persistent El Niño–Southern Oscillation variation during the Pliocene Epoch
Authors: N. Scroxton: Department of Earth Sciences, University of Oxford, Oxford, UK; Now at Research School of Earth Sciences, Australian National University, Acton, ACT, Australia;
S. G. Bonham: School of Earth and Environment, University of Leeds, Leeds, UK;
R. E. M. Rickaby, S. H. F. Lawrence, and M. Hermoso: Department of Earth Sciences, University of Oxford, Oxford, UK;
A. M. Haywood: School of Earth and Environment, University of Leeds, Leeds, UK.
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Cause of crazy weather?
LaNada
http://science.nasa.gov/science-news/science-at-nasa/2011/24jun_wildweather/
Surprised there were no references to climate change.
Jim says: June 24, 2011 at 1:08 pm
[That is such a sad example of an analogy! If you put the Sun near an ice berg, which shrinks the most?]
The Sun:
The Sun releases energy at the mass-energy conversion rate of 4.26 million metric tons per second.
Flunk. Not a constant offset. The tropics barely twitch a degree or two annually or over geological ages. It’s the temperate and polar zones that do all the changing. And warmer temperate and polar zones reduce the discrepancy with the tropics, hence reduce the energy flows, and hence lower the climate and weather variability.
Joe Banks says:
“Funny it was warmer 3 million years ago. Who was emitting all the CO2?”
… and then about 2.8MYA a nearby star went supernova and by 2.5MYA the planet was deep in an ice age …
You could say a warm period is the absence of cold.
El-Niño Phenomenon has become a major problem for tropical countries around the world particularly in the Southeast Asia and the desert parts of Africa. ENSO results into extreme drought that leads to damage to farms and crops. This phenomenon lasts for a couple of months.
peter_ga says:
June 24, 2011 at 5:50 pm
If ENSO is a positive feedback phenomenon where winds blow warm currents to one end of a large ocean, which creates low-pressure, warmth, and convection further reinforcing the winds blowing the warm currents, and this feedback can reverse, then surely this type of oscillation is possible in any climate provided the ocean is big enough, and liquid, and the atmosphere convects.
The positive feedback you describe is sometimes called the Bjerknes feedback:
http://stratus.astr.ucl.ac.be/textbook/chapter5_node4.xml (figure 5.3)
This positive feedback makes the Pacific a “reactive” or “excitable” medium, and thus likely to be subject to nonlinear oscillation, of the Belousov-Zhabotinsky type, as discussed in an earlier post:
http://wattsupwiththat.com/2011/01/25/is-the-enso-a-nonlinear-oscillator-of-the-belousov-zhabotinsky-reaction-type/
If the ENSO is a nonlinear oscillator, it is not surprising to find palaeo evidence that it is persistent, robust and Lyapunov-stable. There is indeed no reason why it should stop.
A more interesting question is when and how did it start. It would be more interesting to go further back in time – 10s or 100s of millions of years when the world map was very different, and look for ENSO type oscillation there – if this is technically possible.