A new consensus?

A few days ago the Global Warming Policy Foundation (GWPF) published a report by Nic Lewis and Marcel Crok (A sensitive matter: How the IPCC buried evidence showing good news about global warming), criticising the IPCC for its dealing with the issue of climate sensitivity, ie. the question of how temperatures will respond to greenhouse gas forcing. Judith Curry wrote the foreword to the report, admitting she had initial reservations about doing so ('I did think twice about writing a foreword for a GWPF publication.  I try to stay away from organizations with political perspectives on global warming.  That said, GWPF has done some commendable things, notably pushing for inquiries into the Climategate affair.  And there really are very few options for publishing a report like this.')

In the report Lewis and Crok come to lower numbers for climate sensitivity, both with regard to Transient Climate Response (TCR) and Equilibrium Climate Sensitivity (ECS), thus making the case for some more optimistic evaluation of the future impacts of climate change. While I am in no position to comment on the merits of this technical discussion, I can offer some observations about the politico-scientific landscape in which the climate change discourse is located.

The report was commented upon by various blogs, and by the Science media Centre which collected statements from Ed Hawkins, Myles Allen and others who gave the report a 'lukewarm' welcome, according to the BBC's environment correspondent Matt McGrath. He thinks that this episode might signify an emerging consensus between diehard contrarians a la GWPF and the IPCC mainstream. Writes McGrath:

Here was one of the world's foremost bastions of contrariness when it comes to man-made climate change, admitting that temperatures were actually rising in response to human emissions of greenhouse gases.
And according to the study, the 2C threshold of dangerous warming would be crossed later on this century.

This raises the interesting question how much of the Lewis/Crok paper is actually endorsed by the GWPF. Providing a platform for an IPCC critical analysis does not mean the organisation shares the details, or the broader message of the paper. Maybe the motivation was to undermine the IPCC's authority. Be that as it may, the perception seems to emerge that there is general agreement between the GWPF and the mainstream in that continued GHG emissions will lead to a warming of global temperatures.

Lewis is quoted as saying 'I am not denying that it's a considerable policy challenge, I am not saying let's bury our heads in the sand, this is trying to present the science.'

And Ed Hawkins says 'If we broadly agree on this, the debate can crucially move on to what action is needed to deal with a warming planet.'

However, McGrath is aware of the fact that 'the GWPF are not highlighting this acknowledgement that man-made emissions are driving rapid changes in our climate, compared to the historical experience' -- which he finds 'strange'.

If my reading is correct that the GWPF does not commit to this implication but is mainly interested in IPCC bashing, the invitation to Lewis and Crok may have led to a new dynamic. Commentators read this as a sign that there is some agreement emerging, despite the appearance to the contrary (because the GWPF emphasises that the sensitivity analysis is different between Lewis/Crok and IPCC).

It is now up to the GWPF to re-state their position with regard to climate policies: is there reason to act or to bury the head in the sand?