The big news today has been the publication of a joint Royal Society/US National Academy position statement on climate change. With my speaking engagement this morning, I haven't had much time to look at it but my initial impression is that it's not as bad as some of the nonsense these two organisations were putting out ten years ago.
That said, the headline message is clearly written with alarmist public relations in mind:
Climate change is one of the defining issues of our time. It is now more certain than ever, based on many lines of evidence, that humans are changing Earth’s climate.
And in many ways, the report is just as bad as the bad old days when Bob Ward issued wild statements purporting to rebut sceptic arguments. It's just that now the bovver boy approach to climate change is all dressed up in a pinstripe suit with shiny shoes and a tie pin. The reason I say this is that it still seems to be set out as a series of rebuttals of peripheral arguments rather than addressing the core concerns over mainstream climate science. For example, you will search the report for the word “sensitivity” in vain, and you learn only that how much warming we might get is an ongoing area of debate. Likewise, while you learn that clouds are a big uncertainty, we are assured that all the models agree that net feedbacks are positive. It goes without saying that aerosols are airily brushed aside, without even a hint that the model estimate of their effect diverges wildly from empirically based estimates.
The project background statement says this:
The Royal Society and the US National Academy of Sciences, with their similar missions to promote the use of science to benefit society and to inform critical policy debates, offer this new publication as a key reference document for decision makers, policy makers, educators, and other individuals seeking authoritative answers about the current state of climate change science. The publication makes clear what is well established, where consensus is growing, and where there is still uncertainty.
I would say that this statement is untrue.