In a time when half a degree more or less warming, might be the difference between tens of millions of people becoming climate refugees, and hundreds of millions (or even billions), the idea that without our forests the planet would be at least half a degree warmer, should give us even more incentive to protect the forests that remain.
Unfortunately the majority of remaining rainforests lie in the developing world, and here people are far more concerned with day to day living. In the developed world, we cut down our forests sometimes hundreds of years ago. We need to be replanting them everywhere we can. In the UK it is thought that we could double our forested area, merely by planting more of our verges and other public unused spaces.
In tropical countries this cooling effect is even higher, at around 1 degree. Many of these countries would become harder to live in with the loss of tree cover.