Could climate indices synchronization be responsible for the current warming?

Question

Ron C has been proposing the synchronization of various climate indices (pacific decadal oscillation, north atlantic oscillation, el nino, etc.) could be responsible for the major climate changes over the past century. He references this paper:

http://www.uwm.edu/~kravtsov/downloads/GRL-Tsonis.pdf

I recall reading a bit about this theory, but I can't find much information about it. There doesn't seem to be much discussion about it on RealClimate as far as I can find.

Anyone have any input on the quality of this theory?

Thanks Trevor and Bob - both very good explanations.

Answer 1

It's fundementally flawed. The events you mentioned have comparatively short wavelength frequencies and varying amplitudes, consequently they're not synchronous and over a period such as a century there will be many peaks and troughs that do not correspond with each other.

If each event were plotted on a graph showing displacement over time and simplified to a harmonic wave you'd see three distinct waves with regular frequency and amplitude. What you wouldn't see is a regular synchronisation of the peaks or troughs of the waves, you may see the occasional good synchronisation but there's as much chance of this being a positive as there is of it being a negative.

The events you mentioned are not in themselves a direct cause or effect of global warming. They don't directly generate heat nor do they have the capacity to retain it.

They do have an effect on climates in so much as regionally and over short periods of time they can affect the weather. The cumulative effect of unusual weather can make a small contribution to overall global warming. However, at the same time it also contributes to global cooling for the same reasons and as such, positive and negative forcings are more or less in balance.

For example, the NAO results in decreased rainfall in some places whilst other places receive increased rainfall. This affects local weather and respectively causes an increase and decrease in the emission of thermal radiation.

I've not explained it very well, hope you can make sense of it.

Answer 2

You will notice the careful approach of a mathematician around line 32 of this paper:

"A major obstacle to this understanding is the extreme complexity of the climate system, which makes it difficult to disentangle causal connections leading to the observed climate behavior."

The theory is very sound. It speaks of the oscillations of various observable phenomena re-enforcing each other and causing a temporary(?) extreme. This is the same thing that happens in the economy. A war, a drought, an unstable financial market all lead to economic depression.

You'll notice that the computer models of climate scientists never seem to have the oversight of statistitians or mathematicians. Indeed, it is these two guardians of scientific rigor who are on the sidelines.

Answer 3

Trevor's explanation is good. Just for reference:

Title: A new dynamical mechanism for major climate shifts
Author(s): Tsonis AA (Tsonis, Anastasios A.), Swanson K (Swanson, Kyle), Kravtsov S (Kravtsov, Sergey)
Source: GEOPHYSICAL RESEARCH LETTERS 34 (13): Art. No. L13705 JUL 12 2007

Answer 4

They're not really saying this is the main cause of late 20th century warming, just a part of it. It's more in the nature of a "feedback mechanism". Check this out:

"Also noted in the text: the authors removed a 2 degree C/century trend due to radiative effects in the 21st century simulation for clarity in the figures. This radiative trend would swamp the relatively small signal of the natural climate shift."

http://planetdoom.blogspot.com/2007/08/grl-paper-on-climate-shifts.html

and, in the paper itself; "suggests an alternative hypothesis, namely that the climate shifted after the 1970s event to a different state of a warmer climate, which may be superimposed on an anthropogenic warming trend."

"hypothesis, which may be superimposed" is not exactly powerful.

Answer 5

I don't think there is a citation associated it with it yet, but A&M has been doing some research on a longterm cycle noticed in the Pacific.

Quote From the link below:

<<<
Giese believes their analysis of tropical Pacific Ocean data indicates long-term upward changes in ocean temperatures precede global surface air temperature changes by about four years. These ocean temperature fluctuations are in turn preceded by an increase in subsurface water temperatures by about seven years.

"Thus, the results suggest that much of the decade to decade variations in global air temperature may be attributed to tropical Pacific decadal variability," Giese observed. "The results also suggest that subsurface temperature anomalies in the southern tropical Pacific can be used as a predictor of decadal variations of global surface air temperature."

For example, in 1976 an abrupt change in the temperature of the tropical Pacific Ocean preceded a rise of two-tenths of a degree in global air temperatures.

"This phenomenon looks like El Nino, but with a much longer time scale - El Nino occurs over a period of from nine to 12 months, but this fluctuation lasts for about 25 years," he continued. "In 1976, the ocean temperature change in question occurred very quickly, moving from cooler than normal to warmer than normal in about a year."
>>>>

http://www.spacedaily.com/news/pacific-02n.html

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And as everyone in research should be carefull about model based speculation or prediction, A&M adheres to that philosophy.

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"Our results don't preclude the possibility that anthropogenic sources of greenhouse gases have contributed to global warming. We're just suggesting that the human forced portion of global warming may be less than previously described."
>>>>

Answer 6

Look here:
http://www.globalwarmingheartland.org/?gclid=CKqq3IXZuY8CFQ1kWAod-lLVcQ