Global Cooling-Wanna Bet?:

Global cooling appears to be the “flavour of the month”. First, a rather misguided media discussion erupted on whether global warming had stopped, based on the observed temperatures of the past 8 years or so (see our post). Now, an entirely new discussion is capturing the imagination, based on a group of scientists from Germany predicting a pause in global warming last week in the journal Nature (Keenlyside et al. 2008).

Specifically, they make two forecasts for global temperature, as discussed in the last paragraphs of their paper and shown in their Figure 4 (see below). The first forecast concerns the time interval 2000-2010, while the second concerns the interval 2005-2015 (*). For these two 10-year averages, the authors make the following prediction:

“… the initialised prediction indicates a slight cooling relative to 1994-2004 conditions”

…

We think not – and we are prepared to bet serious money on this. We have double-checked with the authors: they say they really mean this as a serious forecast, not just as a methodological experiment. If the authors of the paper really believe that their forecast has a greater than 50% chance of being correct, then they should accept our offer of a bet; it should be easy money for them. If they do not accept our bet, then we must question how much faith they really have in their own forecast.

The bet we propose is very simple and concerns the specific global prediction in their Nature article. If the average temperature 2000-2010 (their first forecast) really turns out to be lower or equal to the average temperature 1994-2004 (*), we will pay them € 2500. If it turns out to be warmer, they pay us € 2500. This bet will be decided by the end of 2010. We offer the same for their second forecast: If 2005-2015 (*) turns out to be colder or equal compared to 1994-2004 (*), we will pay them € 2500 – if it turns out to be warmer, they pay us the same. The basis for the temperature comparison will be the HadCRUT3 global mean surface temperature data set used by the authors in their paper.

Here we go again–another one of these public bets among energy or environmental science geeks.

Seriously, am I the only one who’s becomes very tired of these? Is this what the increasingly politicized pursuit of truth via the scientific method has been reduced to? A web-based reality show? Perhaps we should have a web site poll and decide who gets voted out of their profession every week, with the eventual winner getting $100,000 in cash, a Saturn car, and a trip to Disneyland.

The reason I’m so prickly about this one is not just that it’s Dopey Public Bet #483, but that it’s such a critical question. We are struggling to understand how the earth’s climate is changing all around us, even as humanity continues to pump over 27 billion metric tons of CO2 into the air yearly.

At one level, I honestly don’t give a flying fig what the measured temperature does over the next few years. We know that the earth will continue to absorb more heat from the sun than it radiates back into space, so the total heat energy of the biosphere will continue to rise. Whether that energy is in the form of warmer air or warmer oceans or the many billions of tons of ice that are melting every year doesn’t much matter. In the medium to long term nature will run out of convenient places for that heat to go, and that’s when the fun and games really start.

But we are human beings and doing something meaningful about this astonishingly large and nasty mess we’ve created is a political issue. So I remind myself that we’re actually better off if we do experience some Big, Terrifying, TV-Friendly Event, like a total melt of the Arctic sea ice this summer, because it might (just might, mind you) be the ultimate example of “climate forcing” and get us to take more than half-hearted half-steps in the right direction.

And for the record (and to head off the people who will e-mail and ask), if I had to pick a side in this bet I’d go with the RealClimate people, who wrote the above article and are predicting warmer temperatures.