Silly economic prediction

I didn't post about the Fourth National Climate Assessment because of the immediate criticism I noticed about the "economic effect" part that suggested that even under a high emissions path, the effect on the US economy may only be 10% of GDP.

While its seems most media unthinkingly reported the figure as if it was high, lots of people on Twitter with a clue immediately thought that was just ridiculously low.   We're talking an 8 degree temperature rise - that would be a huge change in global conditions (bearing in mind a drop of only 4 to 5 degrees is all it takes to put the planet into an ice age.) 

I don't know that there has been as much discussion about the obvious problems with that figure in the report as there should have been, but And Then There's Physics had a decent post about it, in which the comments are well worth reading.

It would seem there is some hedging in the Report itself about the figure, but in a way it's a wonder that the skeptics have not done more to grab onto this figure to argue that climate change is not a problem.

The lazy JC at Catallaxy has done so - but then he believes the last skeptical thing he ever reads and has now been convinced by Scott Adams, the cartoonist who does videos from up Trump's rectum, that climate models are a fraud.   So gullible:  believes anything that fits the theory "there is no problem."

But it would seem that the professional climate change skeptics have decided to ignore this point and criticise the report in other ways - their familiar refrain of "the science is all too uncertain". 

I don't think the problematic economic prediction is one from an Integrated Assessment Model - but in any event, it is well worth remembering Robert Pindyck's long standing work pointing out that economic forecasts for climate change are a bit of a crock.