Did a recent peer-review study really debunk climate change? [UPDATED]

Did a recent peer-review study really debunk climate change? No, but it did claim as much:

Finally, this study has shown that natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature, a relationship that is not included in current global climate models.

It is well know that ENSO is a major contributor to variability in global temperature, so nothing new there.

But it sounds like they may have found an explanation for the recent warming trend that excludes the CO2 forcing. In fact one of the authors, Bob Carter says as much in the press release:

The close relationship between ENSO and global temperature, as described in the paper, leaves little room for any warming driven by human carbon dioxide emissions.

If true, this would be very significant, so is it?

Nope. The study didn’t even hint at an explanation of the recent warming trend since their methods remove any influence of such trends. As Tamino points out:

the real reason they note such strong correlation is that their analysis method removes all temperature variation which is due to trend — which of course makes it impossible for their analysis to indicate anything whatever about the trend…

The correlation between the derivatives of temperature and of SOI is utterly unchanged when I introduce a trend into either of the time series — no matter how big or small the trend might be. The fact is that their methodology, the process of estimating derivatives by taking 1-year differences, transforms any trend into a constant and thereby eliminates its impact on all variation and correlation.

It’s certainly not true that their analysis shows “natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature.” It shows no such thing; their analysis removes all the effect of trends.

So any claims that this paper explains the recent warming trend is absurd. It does not such thing. It cannot say anything about trends since any influence caused by trends is removed. For more see here, here, here, and here.

But that wont stop the usual deniers from hailing this as a major blow to the theory of global warming. Despite the fact that they were previously pushing conclusions (it’s the sun!) totally incompatible with this study.

The denial group is behaving in a very revealing way…

I would like to start the day with a shorter summary [of the study in question]:

  1. El Nino dominates interannual variability.
  2. Frantic armwaving, accompanied by sciencey-looking charts and graphs.
  3. Therefore, warming is predominantly due to El Nino.
  4. Therefore, very not the IPCC.

Of course conclusion 4 will resonate with the Not the IPCC crowd. It is the conclusion they want, er, I mean, the conclusion that their serious thought has led them to in the past, right?

The trouble is, their argument goes like this

  1. The sun is the source of atmospheric energy
  2. Frantic armwaving, accompanied by sciencey-looking charts and graphs.
  3. Therefore, warming is predominantly due to solar changes.
  4. Therefore, very not the IPCC.

Admittedly, there is some similarity in the discourse. But notice, notice carefully, the subtle difference. These are based on altogether different premises and reach (in step 3) contradictory conclusions. They cannot both be true!…

The Not the IPCC crowd is making a mistake by lining up behind this McLean nonsense. In doing so they demonstrate that they have no scientific hypothesis.

People on record with a solar-centric view who immediately celebrate this result demonstrate that whatever thought they have put into this problem has no scientific component. They simply have a political view that the IPCC must be wrong and will promote anything that sheds doubt on the consensus view.

That’s politics, not science. Which is what we’ve been saying about them all along.

Or a George Orwell put it: “we’ve always been at war with Eastasia

But this is  nothing new. It also begs the question, why would I accept this paper over the thousands that have shown that our GHG emissions are warming the climate. What rational is there to weigh this single paper so heavily? I cannot think of any. Unless, of course, you are grasping at anything that supports your pre-determined conclusion… but that isn’t very rational.

The words of John Mashey seem particularly relevant now:

The publication cycle of the most credible peer-reviewed journals is long enough that a non-expert should be prepared to be wary of any paper only 1-2 years old, especially if it has novel implications counter to mainstream established science.

UPDATE: A comment paper detailing the problems with this study has already been submitted to the Journal of Geophysical Research.

McLean et al. [2009] (henceforth MFC09) claim that the El Ni˜no/Southern Oscillation (ENSO), as represented by the Southern Oscillation Index (SOI), accounts for as much as 72% of the global tropospheric temperature anomaly (GTTA) and an even higher 81% of this anomaly in the tropics. They conclude that the SOI is a “dominant and consistent influence on mean global temperatures,” “and perhaps recent trends in global temperatures”. However, their analysis is incorrect in a number of ways, and greatly overstates the influence of ENSO on the climate system. This comment first briefly reviews what is understood about the influence of ENSO on global temperatures, then goes on to show that the analysis of MFC09 severely overestimates the correlation between temperature anomalies and the SOI by inflating the power in the 2–6 year time window while filtering out variability on longer and shorter time scales. It is only because of this faulty analysis that they are able to claim such extremely high correlations. The suggestion in their conclusions that ENSO may be a major contributor to recent trends in global temperature is not supported by their analysis or any physical theory presented in that paper, especially as the analysis method itself eliminates the influence of trends on the purported correlations.

If deniers are continue to push this study without mention of the comment paper it will serve as further proof that they are dishonest. I wont hold my breath while I wait for a correction from people like Marc Morano.

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