Hansen's Self-Check

Many years ago when I played pickup basketball at a gym or playground, I'd sometimes hear a player derided for his lack of scoring ability with the description "self-check".  That is, he was so bad, no one needed to guard him or 'check' him. 

James Hansen, the political activist posing as a scientist, is in charge of adjusting the US temperature records for NASA GISS.  He's the one responsible for the series of changes which show that temperatures in the past keep getting cooler than originally recorded and recent temperatures keep getting hotter than recorded.  In support of his ongoing crusade to convince the world to cripple its economy, he's come out with another paper preaching gloom and doom.  This sentence is the equivalent of a scientific self-check:

If global warming approaches 3°C by the end of the century, it is estimated that 21-52% of the species on Earth will be committed to extinction.

Really?!  21-52%  Whoa. 

I wonder if that includes Lorenz' butterfly.  My own superduperpooperscooper algorithm computes the likelihood that Hansen's work is full of crap at  99.9% subject to appropriate uncertainty bands.