So how did that global cooling bet work out? (RealClimate comments on 2 year old bet.)

Two and a half years ago, a paper was published in Nature purporting to be a real prediction of how global temperatures would develop, based on a method for initialising the ocean state using temperature observations (http://www.nature.com/nature/journal/v453/n7191/abs/nature06921.html">Keenlyside et al, 2008) (K08). In the subsequent period, this paper has been highly cited, very often in a misleading way by http://climateprogress.org/2009/10/01/interview-with-dr-mojib-latif-global-cooling-revkin-morano-george-will/">contrarians (for instance, Lindzen http://www.heartland.org/events/WashingtonDC09/PDFs/Lindzen.pdf">misrepresents it on a regular basis). But what of the paper’s actual claims, how are they holding up?

(...)

However, with the publication of the October 2010 temperatures from HadCRUT, the first prediction period has now ended, and so the predictions can be assessed. Looking first at the global mean temperatures...



we can see clearly that while K08 projected 0.06ºC cooling, the temperature record from HadCRUT (which was the basis of the bet) shows 0.07ºC warming (using GISTEMP, it is 0.11ºC).

http://www.realclimate.org/index.php/archives/2010/11/so-how-did-that-global-cooling-bet-work-out/#more-5345

Q&A: Professor Phil Jones

B - Do you agree that from 1995 to the present there has been no statistically-significant global warming?
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.

C - Do you agree that from January 2002 to the present there has been statistically significant global cooling?
No. This period is even shorter than 1995-2009. The trend this time is negative (-0.12C per decade), but this trend is not statistically significant.

D - Do you agree that natural influences could have contributed significantly to the global warming observed from 1975-1998, and, if so, please could you specify each natural influence and express its radiative forcing over the period in Watts per square metre.
This area is slightly outside my area of expertise. When considering changes over this period we need to consider all possible factors (so human and natural influences as well as natural internal variability of the climate system). Natural influences (from volcanoes and the Sun) over this period could have contributed to the change over this period. Volcanic influences from the two large eruptions (El Chichon in 1982 and Pinatubo in 1991) would exert a negative influence. Solar influence was about flat over this period. Combining only these two natural influences, therefore, we might have expected some cooling over this period.

E - How confident are you that warming has taken place and that humans are mainly responsible?
I'm 100% confident that the climate has warmed. As to the second question, I would go along with IPCC Chapter 9 - there's evidence that most of the warming since the 1950s is due to human activity.

H - If you agree that there were similar periods of warming since 1850 to the current period, and that the MWP is under debate, what factors convince you that recent warming has been largely man-made?
The fact that we can't explain the warming from the 1950s by solar and volcanic forcing - see my answer to your question D.

I - Would it be reasonable looking at the same scientific evidence to take the view that recent warming is not predominantly manmade?
No - see again my answer to D.