I’ve finally had a chance to listen to some of the evidence presented to the Select Committee on Climate Change and Energy. It’s long and I haven’t listened to it all, so I thought I would jot down a few thoughts. I’ve also only listened to the second half, which took evidence from Richard Lindzen, Donna Laframboise and Nicholas Lewis. These 3 would probably be regarded as on the skeptic side of the argument. This first half took evidence from Peter Stott, Brian Hoskins, and Myles Allen. If I get a chance, I’ll also listen to the first half.
I think it’s unfortunate that it was divided in the way that it was, in that it makes it seem as though the committee sees it as a debate of two halfs. If you think all 6 are experts, then why not simply divide them randomly. If this isn’t possible, or sensible, then maybe that says something in itself.
I’m actually finding it quite hard to summarise what was said. Donna Laframboise said very little and saying little about what she said, is probably the best option. She did say (and I paraphrase slightly) I’m a journalist with no scientific background whatsoever and that would appear to be consistent with the rest of what she said.
I found Richard Lindzen very unconvincing, which surprised me a little. I had thought he might come across in a much more convincing manner. Much of what he said was along the lines of there’s no evidence for alarm, or there is evidence that we have no need to be alarmed. Well, yes, it’s possible that the actual warming will be on the low end, but there’s a chance (and quite a good one) that it will be near the mean of the range, or higher. So, although there’s evidence that we have no need to be alarmed, there’s also evidence that we should be alarmed. He also made some statements about models not being good and that they didn’t have sufficient resolution. He also disputed the evidence for recent accelerations in sea level rise. Additionally, he suggested that the less bright students went into climate science, while the brightest went into physics and maths. I wonder what he thinks of the physicists and mathematicians who’ve become climate scientists.
He said something, though, that I think is either completely wrong, or poorly defined. He claimed, that if climate sensitivity is low (around 1oC) it will warm within a few years. If it’s high, it will take centuries. Hence, he seemed to conclude, that many decades will allow us to distinguish between low and high. Depending on precisely what he’s considering, if we are 1oC below equilibrium it will take decades to warm because of the inertia of the oceans. So, I think he’s wrong to say it will take a couple of years. Also, Otto et al. (2013) have used decades worth of observations to estimate climate sensivity, and the mean value for the equilibrium climate sensitivity is above 2oC.
I actually thought that Nicholas Lewis did quite well. I’ve described him as having the academic credentials of a good PhD student. However, he clearly has had a past career and his general expertise was evident. He seemed quite comfortable in front of the committee. I also think that what he presented was okay. He didn’t really say anything that I would outright dispute. He mentioned that estimates for the influence of aerosols has reduced since AR4 and that climate models are using aerosol forcings that are too high and hence they’re over-estimating the warming influence of CO2. This may well be a factor. He mentioned that the recent slowdown in surface warming may well simply be a consequence of natural variability. He, however, did make the rather standard climate scientists aren’t experts at statistics claim. I don’t know if this is true or not, but I’d be surprised if it was. Most scientific disciplines now have experts at statistics. There clearly are some who are not, but generalisations are rarely true.
The main thing he said that I would dispute is that climate sensitivity is likely 60% lower than that suggested by the models. I don’t know where he’s getting this from. The model trends are higher than observations suggest (by maybe 30%) and energy budget estimates are coming out lower than the model estimates. So, maybe there’s a 30% correction. However, already the energy budget estimates are rising as we refine our observations and we have paleo-climatological estimates that are consistent with the modelling estimates. Also, the mismatch between the models and the observations could be for many different reasons. So, yes the climate sensitivity could be lower than model estimates suggest, but – then again – maybe not.
So, that’s a rather quick summary as I’ve promised to clean the kitchen and make some soup. I may try and listen to some more and maybe write a bit more at a later stage. Then again, maybe I’ll have better things to do.