…allows trees to get by on less water. Of course, this can’t possibly be allowed to be good news:
The immense volume of water that trees pull out of the ground winds up in the atmosphere, helping supply moisture to farming areas downwind of forests. So if trees use less water, that could ultimately mean less rain for thirsty crops in at least some regions of the world.
It could mean lots of things — good, bad and indifferent — and the vast majority of them unpredictable, given the non-linear nature of the equations and our lack of understanding of the complexity of all the interactions, which is why it’s crazy to be attempting to make costly public policy on the presumption that Carbon Is Evil.