This is true and more land will become tillable such as vast areas of Siberia and Canada. There will likely be far more rain forest area and regular forests. The past has shown this to be true which leads me to ask the question, "Why all the doomsday prophecies from people like Al Gore?"
IMO, capping CO2 emissions won't solve anything and furthermore it is impossible to accomplish. It will only lead to the squandering of our dwindling economic reserves to solve a problem that doesn't exist. Energy conservation and improvements in efficiency are good for economic, environmental and reduction of poverty reasons among others but if done to the extreme will starve hundreds of millions of people. Countries will be going to war over food. It would also destroy the global economy and the standard of living of the developed countries. This whole fascist environmental movement that has developed is nothing more than a money grab and a way to gain more control over the masses. It can't be done with force so they are trying to scare, bluff and brainwash us into it.
The problem is that global warming is going to be proven as a scam and will further discredit these wacko environmentalists. Then when a real problem arises these wackos will have cried wolf so many times that no one will listen to the people that have valid causes. It is a general problem with politicians on the left and right in that they continually exaggerate reality to scare people into doing their bidding.
The latest scare is this supposed economic meltdown. It is the politician's (especially the left) way of spending money we don't have on an endless list of earmarks and entitlement programs we simply can't afford. When all this money is spent, billions of it will find its way into politician's and their family member's bank accounts. The Democrats are going to try and use it to buy their way into getting re-elected for decades. The sad thing is we are going to let them do it and not even ask to be kissed before they screw us.