Given that the whole Royal Society Twitter saga relates partly to the possibility of an abrupt methane release, I thought I might post this video that I found on Climate Denial Crock of the Week (I hope Peter Sinclair doesn’t mind me using it). It’s Richard Alley explaining that our current understanding is that although there is a lot of methane on the sea floor, it is very unlikely to be released abruptly. It may well provide a feedback, but a methane “bomb” is unlikely.
This got me thinking a little about these low-probability, high-risk events. Of course, we should study and try to understand these processes, but I can see why they shouldn’t play a big role in the policy debate. We’re unlikely to drastically change our economy because of something very unlikely, even if it does present a high-risk (although how we as a society react to unlikely events does suggest that we don’t always behave in this way). We also have plenty of reason to act without focusing on such possibilities.
There is, however, a role that they can play and that some may not recognise. Richard Alley brings this up at the end of the video, which is why I thought I might mention it. There are various ways in which we can estimate how our climate will evolve under increasing anthropogenic forcings, and we can produce some kind of best estimate for the likely outcome. However, it’s not exact and we know that it could be “better” than this, and it could be “worse”. So, in some sense, there’s a symmetry – an approximately equal chance of these being “better” or “worse” than our best estimate (assuming it’s the median).
However, when it comes to the unexpected outcomes/events, this symmetry – I think – breaks. The chance that something unexpected could make things “better” is extremely unlikely. It would almost need to be fine tuned. It is much more likely that unexpected outcomes will makes things worse. So, although I can see why focusing on these unexpected events may not makes sense from a policy perspective, I do think that we can’t ignore that – if they do occur – they will likely make things worse. They also, probably, depend on the amount and rate of future warming, and so add an extra reason why we should really be seriously considering avoiding the higher emission pathways.
Anyway, that’s my view, for what it’s worth. Watch the video; Richard Alley is an extremely skilled science communicator.