http://gristmill.grist.org/story/2008/2/28/134525/930/#comment7

Without a switch to organic agriculture AND elimination of as much human caused GHG as possible and as much land returned to natural carbon sink as possible, it won't be stopped.

But with all these steps all around the globe, it could even be reversed.  How much time do we have?

If it happened over 20 years with half in 10 years, that would do it.  Waiting any longer is crazy.  Those positive feedbacks like methane hydrate ice melt and exponential glacial and ice cap melting, that darkens the earth, absorbing more solar heat, are waiting to take off.

We have a mass delusion going around that fuel farming, clean coal, flex fuel gas guzzling, and nuclear power will be be positive steps.  They aren't, in fact they all increase gHG and delay real solutions.