From an article yesterday in the NY Times, May 9, 2012, nytimes.com/2012/05/10/opinion/game-over-for-the-climate.html :
Game Over for the Climate
By JAMES HANSEN
Hansen, director of the NASA Goddard Institute for Space Studies, is the top climate scientist in the U.S. His article echos an American Geophysical Union conference paper he gave 3 years ago (read esp p. 24): columbia.edu/~jeh1/2008/AGUBjerknes_20081217.pdf
In the NYT article he's referring to something Obama said about how Canada will be exploiting the Candian tar sands "regardless of what we do," which according to Hansen would spell extreme disaster long term for humanity, and even a lot of serious problems short-term. He also makes suggestions for something better than a Cap&Trade scheme.
This is important, since JPII told us in 1990, that it's everyone's responsibility to mitigate global warming, and BXVI has been repeatedly telling us this.
For those interested in reading or making suggestions about how we can mitigate AGW (in ways that don't break our piggy banks), I've started a thread at forums.catholic.com/showthread.php?t=656903