The Devil His Due

There's something to be said for appreciating what your usual opponents say that is good and worthwhile.

I'm a long way from an unalloyed admirer of Roger Pielke Jr., but once in a while, too often for pure randomness, he hits a nail on the head. And he has two pieces right now that I'd put in that category and then some. I think they are important and shouldn't be missed. The more recent one is about the innumeracy of a proposed carbon neutrality solution in Australia. (This is the Dyson solution, isn't it?) Quoth Roger:

It is easy enough to check the video of the interview to see what Hunt actually said (starting at 9:30) and to realize that the transcript on his official web site is falsified.

which is strong language, and happens to be true.

But even more interesting is his piece on the obsession with global mean surface temperature, which I think is compelling. GMST is not the problem. Carbon is the cause, local climate disruption is the impact. If GMST goes up a lot, the impacts cannot be small, but if GMST does not go up a lot, the impacts may still be large. Roger Jr. explains succinctly. He avoids getting too deep into his father Roger Sr.'s peculiar understanding of the physics, with which many of us take issue, and simply makes the point that huge climate changes are possible with zero temperature change in the global mean. A point often lost in the shuffle by the stickerati, (including to some extent Mann, Briffa, Jones, McIntyre, Watts, Liljegren, Hausfather, Barnes, Christy, Spencer, and now Muller) who to various degrees and various extents seem to think that climate science somehow boils down to a single time series, and stands or falls on the accuracy thereof.

This is what Roger Jr says about it. Though a bit understated for my taste, it is substantively exactly right in my opinion:

In the real world, the effects of increasing carbon dioxide on human and ecological scales are well established, and they include a biogechemical effect on land ecosystems with subsequent effects on water and climate, as well as changes to the chemistry of the oceans. Is it possible that these effects are benign? Sure. Is it also possible that these effects have some negatives? Sure. These two factors alone would be sufficient for one to begin to ask questions about the worth of decarbonizing the global energy system. But greenhouse gas emissions also have a radiative effect that, in the real world, is thought to be a net warming, all else equal and over a global scale. However, if this effect were to be a net cooling, or even, no net effect at the global scale, it would not change my views about a need to consider decarbonizing the energy system one bit. There is an effect -- or effects to be more accurate -- and these effects could be negative.

Of course, not mentioned yet is that action to improve adaptation to climate doesn't depend at all on a human influence on the climate system, warming or cooling or whatever. Adaptation makes good sense regardless. So clearly my policy views on adaptation are largely insensitive to any issues related to global average temperature change.

The debate over climate change has many people on both sides of the issue wrapped up in discussing global average temperature trends. I understand this as it is an icon with great political symbolism. It has proved a convenient political battleground, but the reality is that it should matter little to the policy case for decarbonization. What matters is that there is a human effect on the climate system and it could be negative with respect to things people care about. That is enough to begin asking whether we want to think about accelerating decarbonization of the global economy.

To fully assess whether accelerated decarbonization makes sense would require us to ask, are there any other good reasons why accelerated decarbonization might make sense? And it turns out, there are many.

Yep.

In the end the GMST time series is almost purely a distraction. If we have that right or wrong matters far less than it's made out to. The other 9o% of the WG I reports are far more compelling, if a little harder to understand. That's why I think the whole matter reduces to empty gossip.

Update: Nick Barnes (along with a CCF colleague) comments below on his inclusion in my list of the GMST-obsessed in an interesting way. Yes, this is the beginning of my response to Dan Olner: it is a useful communication tool, and his broad understanding is correct. But in a sense it does not HAVE TO BE correct; the step that goes from heat to temperature is far more complicated in detail than the simple explanation allows. This is the point that Lindzen and Spencer stubbornly adhere to. It seems clear that they are wrong, but they can't be refuted at the level of Dan's model.

It's hard to come up with a scenario where the sensitivity is negative, but it's not that hard to come up with one where it is very small. My point, and Roger Jr's point, is that even if true, even if the sensitivity is small, that doesn't suffice to argue that anthropogenic disruption of climate is not worth worrying about.