New Articles in the journal Nature say climate change is worse than thought, is happening faster with greater impacts and is going to be more difficult to control

To limit warming to 2 degrees C by 2050, the world must limit greenhouse gas emissions to 275 gigatons between 2000 and 2050.  Considering that we have already emitted nearly one third of this 275 gigatons in nine years, this is going to be "extremely difficult" says the author of the report (Meinhausen). The research findings from a new super computer climate model were reported today in the journal Nature.

Meinshausen et. al., Greenhouse-gas emission targets for limiting global warming to 2 °C, Nature April 30, 2009.