Tamino has an interesting post about the recent slowdown in surface warming. His post essentially points out that if you consider a long enough time interval, it’s pretty hard to find evidence for a slowdown. I do think we have had slower surface warming in the last decade or so than in the previous decades, but I think he is right that in 10 or 20 years time it will not be particularly evident that we went through a period of slower surface warming in the early 21st century.On that note, I thought I might briefly mention a recent paper by England, Kajtar & Maher called Robust warming projections despite the recent hiatus. Essentially it selected only those climate models that had a 14-year period during the interval 1995-2015, with a surface temperature trend of 0.09oC per decade, or less. This gives 19 (out of 90) RCP8.5 models, and 19 (out of 108) for RCP4.5.
The result is shown by the figure on the right and illustrates that the impact of the “hiatus” on projections by 2100 is relatively small; almost negligible. This makes reasonable sense. If the hiatus is partly due to interval variability, then we would expect accelerated warming quite soon and we would expect periods of faster than average warming to largely compensate for periods of slower than average warming. Of course, there are other explanations for the “hiatus”, including more volcanic activity than included in the models, and smaller forcing changes than was expected. None of these would, however, change the projections either.
Anyway, thats all I was going to say. It is likely that the “hiatus” is broadly irrelevant both for the reasons indicated in Tamino’s post and because even if there has been a recent slowdown in surface warming, it probably won’t have a noticeable effect on the long-term projections.