Our agricultural methods are going to have to change substantially within the next few decades whether we face a warming catastrophe or not, since global agricultural productivity is on a downtrend due to desertification and loss of arable soil as global food needs rise.

Of course, we've jacked up the carrying capacity of the earth several times before, and it's certainly possible to do it again. Like many problems, this would be easy to address if we had access to a superabundance of energy, so any major advancements on that front in the near term would make it possible to avert catastrophe.