After 2014 was the hottest year in the instrumental temperature record, it looks like 2015 will beat this record, and the UK Met Office suggests that 2016 will then beat that. If so, I think this would be the first time in the instrumental temperature record that three consecutive years have each been the hottest on record.
The expected El Niño finally arrived. It was initially reported as being weaker than expected and then became incredibly strong. It is clearly been a contributing factor to this run of warmest years. All we have to wait for now are the claims of no warming since 2015.
We’ve also had some pretty extreme weather in 2015. The UK has had extreme precipitation and flooding, which may be partly due to the El Niño and partly due to climate change. South Africa is in the midst of the worst drought for a generation. This Northern Hemisphere winter has also been incredibly mild, with temperatures in the Arctic potentially reaching values 30oC, or more, above average.
I’ll make a quick comment about climate change and extreme events. Clearly all the above events are simply weather events and we can’t easily attribute anthropogenic influences to a single event. However, two robust expectations of anthropogenically-driven climate change is that we will – on average – warm, and we will see changes to the hydrological cycle; probably manifesting itself as an increase in the intensity and frequency of extreme precipitation events. Not only can we not continue to ignore that AGW is probably at least partly responsible for the extreme events we’re experiencing, we should also be using such events to inform how we should respond to what the future is likely to bring.
It’s also time to recognise that not being able to make a robust attribution does not mean there is no link. If anything, given our understanding of physical climatology, it would be more surprising were we to discover no link, than to find that there is indeed a link. Also, because of our influence, the the environment in which these events are occuring is different to what it was before.
As far as the blog is concerned, there was a bit of a focus on climate sensitivity, in particular those estimates that rely on Bayesian methods. This lead to a related discussion on Andrew Gelman’s blog. Andrew also commented on Doug Keenan’s challenge. We also discussed drawing down atmospheric CO2, and had a few posts from Michael Tobis, most of which had titles that were song lyrics from one of my favourite groups.
That’s all I was really going to highlight. It’s also my impression that climate denial has become more marginal in 2015 than it has been before. It either seems less prominent, or those who promote it are becoming more obviously extreme. On the other hand, it might be that I’ve simply become more immune to it. I expect little better from some and see little chance that some will stop promoting their nonsense. So maybe nothing has really changed; I’ve just become better at blocking out the noise. Either way, 2015 has been an interesting year and I would expect 2016 to be even more so.