I was wanting to briefly highlight a David Roberts post called the two key points that climate “skeptics” miss. I was only going to comment on one of the points, which was about the convergence of all the evidence, typically referred to as consilience. Given the continued fighting about consensus studies, it’s easy to forget the real reason why our understanding of climate change is robust; it’s because of the combination of all the evidence that leads to a coherent, and consistent, picture of the likely consequences of anthropogenic CO2 emissions.
Of course, this doesn’t mean that our understanding is perfect, or that there isn’t uncertainty. The basic idea is essentially that all the different lines of evidence are consistent, even if not precisely the same. Also, not each line of evidence will be equally strong, and there will still be uncertainty associated with each line of evidence. This is where the problem comes in. A typical “skeptic” tactic is to attack, and focus on, a particular line of evidence. Adjustments to the temperature data. The “pause”. Ocean heat content data coverage. The hockey stick. Climate models. Of course, if you focus on something specific, you probably can find something to criticise, even if it isn’t particularly significant. It’s highly unlikely that any single line of evidence will be perfect, and so if you really want to find fault, it’s probably quite easy to do so.Of course, what typically happens is those who do find something to criticise, either blow it out of proportion (the hockey stick, and adjustments to the temperature data being classic examples) or cherry-pick in such a way as to make something look far worse than it actually is. A particular example is a graph generated by John Christy, purporting to show a huge discrepancy between climate models and observations. The exact details of this graph have never been made clear, but many highlight it as proof that climate models have failed. The problem, though, is that if you do the comparison properly – as Gavin Schmidt has done to generate the graph on the left – the models and observations appear consistent.
In truth, my main reason for writing this post was to highlight the graph above and to put it into some kind of context. Having done so, I will now stop.