Matt Ridley has a particularly silly article in the Wall Street Journal called Whatever happened to Global Warming. In his article he says
Well, the pause has now lasted for 16, 19 or 26 years—depending on whether you choose the surface temperature record or one of two satellite records of the lower atmosphere. That’s according to a new statistical calculation by Ross McKitrick, a professor of economics at the University of Guelph in Canada.
It has been roughly two decades since there was a trend in temperature significantly different from zero. The burst of warming that preceded the millennium lasted about 20 years and was preceded by 30 years of slight cooling after 1940.
This is based on a new paper by Ross McKitrick in which he determines what length of period prior to 2009 is required so that the trend plus 2σ uncertainty interval in the temperature record does not intercept zero. Richard Telford has already done a wonderful take-down of this work by showing that 15-20 year periods are quite possible even if the underlying long-term trend is constant and rising. What Ross McKitrick and Matt Ridley are almost certainly doing is making a Type II error. He’s accepting the null hypothesis (we’re not warming) when we almost certainly are. The comments by Dikran and Chris Colose on Richard’s post are also worth reading.
Matt Ridley goes on to say
This has taken me by surprise. I was among those who thought the pause was a blip. As a “lukewarmer,” I’ve long thought that man-made carbon-dioxide emissions will raise global temperatures, but that this effect will not be amplified much by feedbacks from extra water vapor and clouds, so the world will probably be only a bit more than one degree Celsius warmer in 2100 than today. By contrast, the assumption built into the average climate model is that water-vapor feedback will treble the effect of carbon dioxide.
Well, here Matt has completely ignored the ocean heat content data and the continually reducing ice mass, both of which indicate that we’re accruing energy at a rate that is consistent with what we’d expect. The surface warming is only associated with a few percent of planetary energy imbalance, and so it’s not at all surprising that it shows significant variability.
And then, quite remarkably, concludes with,
But now I worry that I am exaggerating, rather than underplaying, the likely warming.
Don’t worry Matt, I think many people still regard you as an out and out denier. Of course, I would never call you that, but your concern that you’ve been a little alarmist is entirely misplaced.
When I see this kind of thing it makes me realise that there’s no real point in discussing this with such people. We’re talking a completely different language. If you want to consider anthropogenic global warming, you really should consider all the evidence. You can’t consider a subset of the evidence and then draw conclusions about whether we’re warming or not. Additionally, these discussion invariably end up being ones in which you’re challenged to show where there’s an error in their calculation. There’s not necessarily an error, but context is crucial. It’s a little like (and I exaggerate) someone doing a simple calculation (2 + 2 = 4), claiming that they’ve shown that Einstein is wrong, and then insisting that you can’t prove them wrong until you find the error in their calculation. I’m sure Willard would have some term that described such forms of argument.
I’ll finish this post by mentioning a relevant article by Richard Betts on Climate Revolution called Pooh sticks, pauses, and predictability. It’s a good post, and it reminded me that – at university – we had a student magazine that once included the classic drawing of Pooh and Piglet playing Pooh sticks, but in which they were facing the other way. My mother claimed that it had ruined Winnie-the-Pooh for her. Richard finishes his post with
Claiming that long-term warming won’t happen because the ‘pause’ was not specifically predicted is like saying that you can’t be sure the river will flow downhill because you can’t predict the winner at pooh sticks.