There are some aspects of the climate debate where the arguments taking place seem to be based on nothing at all, when you go back to first principles and try to start from the beginning. Tim Osborn started a long twitter debate by saying that sceptics “haven’t provided a credible explanation for observed warming”. Another climate scientist, Robert Rhode, followed up on the “no credible explanation” question. I asked them both
and there was a stony silence from both of them. The point is, of course, that this long temperature record for Central England, going back over three centuries, shows that nothing unusual is happening at all. The current rate of warming is no greater than it was at various points in the past. Now of course the CET isn’t global temperature, and unfortunately there isn’t a global record going back that far. But for the global data sets that do exist, the warming in the early 20th century was very similar to the warming in the late 20th century, so the same issue arises (or rather, again, there is no issue to explain). Whatever “caused” the warming that seems to have occurred from about 1700-1740 could also have “caused” the more recent warming. So there is nothing that needs to be explained.
Two days after the silence from Osborn and Rohde, John Kennedy came up with this, which I found quite remarkable:
I’m not entirely sure what John is trying to say in this tweet. If he really means “recent climate change” then he hasn’t understood the simple “nothing to explain” point, but he’s smarter than that, and the links to the papers show that the real message from climate science is this:
The nothing unusual that is happening in the CET data can be explained by human influence.
The first paper is by Karoly and Stott, neither of whom I would trust to add 2 + 2. Recall that Karoly was the senior scientist behind the attempt by Gergis et al to create a hockey stick graph using a bogus method that got called out by Climate Audit leading to the withdrawal of the paper. Stott has a record of making misleading claims to the public.
The paper claims that “the recent warming is larger and longer duration than any other period in the record” which just isn’t true. They claim that, according to their computer simulations, natural fluctuations can’t have caused the warming seen in CET over the last 50 years. The obvious question of what caused the very similar warming in earlier times is ignored.
One climate scientist (the one who does not believe in the existence of Jaime Jessop) decided that the way out of this problem was to declare that “We must get away from the idea that climate science is driven by observed climate change”.
It’s a similar story with the attribution of extreme weather events, something we’ve discussed here from time to time — see for example this recent article by Geoff and this one on floods by Jaime. The IPCC AR5 summary statement on floods is
In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale.
For tropical cyclones, they say
Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century and it remains uncertain whether any reported long-term increases in tropical cyclone frequency are robust, after accounting for past changes in observing capabilities
and they include this graph, which shows no long-term trend in storms hitting Australia and the US over the last hundred years.
So again, nothing unusual is happening, and there is nothing to explain. But there is now a whole industry within climate science trying to show that this nothing is caused by human activity.