“Recent observations confirm that, given high rates of observed emissions, the worst-case IPCC scenario trajectories (or even worse) are being realized. For many key parameters, the climate system is already moving beyond the patterns of natural variability within which our society and economy have developed and thrived.

(http://climatecongress.ku.dk/newsroom/congress_key_messages/)

worst case scenario of the IPCC-2007 (AR4) is defined as “scenario A1F1″