McLean’s folly and the climate clueless

By Gareth Renowden 13/03/2011


In an astonishing press release issued last week, the New Zealand Climate “Science” Coalition predicts that 2011 will be the “coolest year globally since 1956 or even earlier”. The C”S”C bases its prediction on the work of Australian “computer consultant and occasional travel photographer” John McLean. Hot Topic readers will remember McLean as the lead author of a rapidly rebutted 2009 paper (written with Chris de Freitas and Bob Carter) which claimed that El Niño/Southern Oscillation (ENSO) events were a driver of global temperature increases. I covered the full story at the time: see Mother Nature’s Sons and subsequent posts.

One unoriginal finding of the McLean paper was that global temperatures were affected by ENSO events — warming after El Niños and cooling after La Niñas. Last year NZ C”S”C member Bryan Leyland used this to “predict” a coming cooling, which was lapped up by the usual suspects. In January this year, Leyland predicted cooling would continue until at least June. Now McLean has taken this a step further by predicting that temperatures will plunge to that of a cool year 50 years ago. There’s no justification for this prediction in the press release, beyond McLean pretending that his 2009 paper showed that CO2 was a minor player in global temperature change.

Unfortunately for the credibility of all involved, McLean’s prediction is utter unphysical nonsense. Here’s why…

I wanted to find out how McLean’s prediction looked in the context of the long term temperature record, so I downloaded the NASA GISS series data (available here), and plotted it on a graph:

Maclean1956

I’ve shown the 1956 temperature (-0.17ºC referenced to the 1951-80 average) as a blue line. The red cross on the end is where the 2011 temperature would plot if McLean’s prediction were to come true. I also looked through the data series for the biggest single year cooling event. That was a fall of 0.29ºC from 1963 to 1964, helped along by the explosive eruption of Mt Agung in Bali. The higher red cross labelled “1963 cooling” is where 2011 would plot with the same temperature fall. By way of contrast, the largest recent cooling not benefitting from volcanic help was 1998 – 1999, and “only” 0.24ºC.

McLean wants us to believe that global temperatures will fall by 0.8ºC in a single year. There is no precedent for such a large drop in the last 130 years — the variation between years is much smaller, not often exceeding 0.2ºC. The reason for that is easy enough to understand: there’s a lot of thermal “inertia” in the climate system, provided by the oceans that cover 70% of the planet’s surface. The only way global temperatures could fall by 0.8ºC in a single year would be for the amount of solar energy reaching the earth’s surface to be hugely reduced — and the only natural mechanism that could do that would be a volcanic eruption (or series of eruptions) of truly vast size. It won’t happen because of a single La Niña event, however strong and long one might be.

Here’s my prediction. Barring the volcanic equivalent of a nuclear winter, 2011 will probably turn out to be slightly cooler overall than 2010, because of the current La Niña (which may or may not fade away later this year). Given a really steep fall like the one from 1963 to 64, we might have the coolest year since… 2000. That’s what 50 years of heat accumulating the system means. And the underlying warming trend will continue.

You might think that the “scientists” and “experts” at the NZ Climate “Science” Coalition would have noticed that McLean’s temperature forecast is rubbish. After all, they have noted scientists like Bob Carter and Chris de Freitas as members and advisers. Unfortunately Chris and Bob appear to have a bit of a blind spot when it comes to criticising their erstwhile co-author. Meanwhile, the Climate “Science” Coalition, and everyone involved in promoting this sorry little weather forecast are shown, yet again, to be the Climate Cluelessâ„¢.

[PS: I haven’t got round to formulating a bet with Bryan Leyland on “warming” v “cooling” (yet), but if he’s willing to bet that McLean’s right, I’ll very happily take the other side.]

[Robert Palmer]