Abstract of the Paper appearing in the Journal of Geophysical Research: Time series for the Southern Oscillation Index (SOI) and global tropospheric temperature anomalies (GTTA) are compared for the 1958−2008 period. GTTA are represented by data from satellite microwave sensing units (MSU) for the period 1980–2008 and from radiosondes (RATPAC) for 1958–2008. After the removal from the data set of short periods of temperature perturbation that relate to near-equator volcanic eruption, we use derivatives to document the presence of a 5- to 7-month delayed close relationship between SOI and GTTA. Change in SOI accounts for 72% of the variance in GTTA for the 29-year-long MSU record and 68% of the variance in GTTA for the longer 50-year RATPAC record. Because El Niño−Southern Oscillation is known to exercise a particularly strong influence in the tropics, we also compared the SOI with tropical temperature anomalies between 20°S and 20°N. The results showed that SOI accounted for 81% of the variance in tropospheric temperature anomalies in the tropics. Overall the results suggest that the Southern Oscillation exercises a consistently dominant influence on mean global temperature, with a maximum effect in the tropics, except for periods when equatorial volcanism causes ad hoc cooling. That mean global tropospheric temperature has for the last 50 years fallen and risen in close accord with the SOI of 5–7 months earlier shows the potential of natural forcing mechanisms to account for most of the temperature variation. Received 16 December 2008; accepted 14 May 2009; published 23 July 2009.
Timbikes, I've reached the point where I don't expect you to understand what you post, and I don't even expect that you've bothered to download and read the entire article as I just did ($9 at JGR). If anybody wants to read an intelligent analysis of it, read Tamino here: Old News Open Mind Tamino explains it pretty clearly. It is well known that variation in the ENSO is highly correlated with variation in global temperature. This is not new. The authors take first derivatives of the data (ENSO index and temperature), then look at correlation. Doing that (first derivatives) removes all trend from the data. Their analysis therefore is completely blind to the trend, and their correlation analysis only looks at variation around trend. That's not opinion, that's just arithmetic. So, to be completely clear about that, there is zero empirical analysis in that paper that relates to temperature trends. They de-trend the data by taking first derivatives before they check for correlation. (Which is a perfectly reasonable thing to do when looking at correlation, and I typically include a time trend when I run regressions myself, if the trend is not the central issue.) Nevertheless, they bring in a discussion of trends via what Tamino correctly describes as "hand waving" at the end of the paper. They note that the mean ENSO index changed between two periods. (Which, as Tamino says, is a change, not a trend). Again, to be completely clear, nothing in their empirical analysis addresses trends. it cannot. They nevertheless informally suggest, without any numerical analysis that I can see in the paper, that the one-time shift in the average ENSO index "may" explain the trend. Probably the most telling statement in the article is this, without citation or attribution: "Climate modelers acknowledge that their models do not adequately hindcast average global temperatures from 1950 to 1990 and apply a human influence factor to make up the deficit.” Hahah. As if all the complexity of the General Circulation Models is just a big ol' fudge factor that they made up. Instead of detailed modeling of the underlying physics. (As opposed to taking the correlation between first derivatives of two time series, as these authors did.) And of course this entire analysis begs the question: Do you think the ENSO itself generates heat? Because, over the long term, if it causes a trend in global temperature, it has to be generating heat somehow, and putting that energy into the atmosphere. What is that mystery source of energy? Or, does all the energy absorbed and released over the ENSO cycle ultimately come from the sun? Hey, I think it has to be the latter. In which case, over the long term, it's a whole lot more plausible to suggest (without proof) that global warming may cause a shift in the ENSO regime. Putting the causality the other way around suggests that somehow the ENSO itself is generating heat. In my mind, this is but one step away from arguing the following: Hey, look at the great correlation between mean ocean water temperature and mean atmospheric temperature. Well then, mankind isn't causing global warming, that great correlation proves that it's the ocean that causing our temperature trend. Oh, sorry, did I say the entire ocean? I meant just the southern pacific -- it's the water temperature of the southern pacific that's causing global warming, not mankind. Oh, is that the ENSO? Ok, then the ENSO is causing global warming. Where does the ENSO get the energy to be "causing" global warming? Beats me. That's not my department. I only work with correlations, not with models of the actual physical processes generating the changes. ADDENDUM: OK, Realclimate's Friday roundup addressed this one, with the interesting added information that, based on their published analysis, you get the same trend whether or not you account for ENSO. Well worth the read, as usual: http://www.realclimate.org/index.php/archives/2009/07/friday-round-up-3/ You can see the discussion, with graphs, published a year ago, demonstrating that removing the ENSO signal from global temperature data leaves the trend relatively unaffected, here: http://www.realclimate.org/index.php/archives/2008/07/global-trends-and-enso/
Worth checking out your links - although it is interesting that the paper passed peer review and got published if it is as flawed as you say Tamino suggests. I guess peer reviewed publication only counts for something when it supports AGW, right?
My personal unscientific theory is that of course there are natural trends up and down in global temps. My concern is that man made actions COULD influence these trends so severely that once man made input is factored in, the natural healing process of the atmosphere MAY not be able to counter all the accumulated 'trends' up or down. If that is even a POSSIBILITY then the situation deserves to be addressed. *BONUS1* By attempting to reduce man made influences we wean ourselves off foreign sources of energy thereby making ourselves more independent of artificial fluctuations, and less susceptible to influences beyond our control. I think the present buzz word is that it increases our national security. *BONUS2* By removing man made sources of global warming we get to live in our more natural sphere, lessening chances of cancers and other illnesses. Notice I don't say anything about good, bad, yes or no to the global warming politics. Once an issue has been discovered like global warming, no matter what the cause, it behooves mankind to heed the warning to not exacerbate the unnatural discovery of mankind's input. Goes for air, water and terra pollution. Furthermore, if these kinds of negative trends to our natural environment are made simply for the enrichment of a few people all the more reason to put a halt to what we can control. Now, if say, global warming were to be discovered to be caused by a greater population simply exhaling carbon dioxide, then who am I to say stop the untoward trend? When we are all to blame then it's one thing, when a small portion of the population endangers the whole species then it's alltogether another matter.
This was fun. It will be interesting to see how the authors react to the criticism. Now, let me display my limited intellect for everybody's pleasure: I take the article's methodology to mean that no acceleration in global warming has been identified. This is not expected from our conceptual framework, although I think rather easily explained by recent short-term natural forcings.
