What are rainforests good for?

The above picture is a false-color picture of the OLR, Outgoing Longwave Radiation of the Earth in the early nineties, made by NOAA. You can see the contours of the continents. Blue on the map represents 'cool' radiation, while red represents 'hot' radiation. One could also say exergy-poor and exergy-rich radiation. (Never heard about exergy? Go to my homepage and look up thermodynamics).
What is interesting with the picture is that the temperature radiation is not evenly spread over the world. It is not so, that the radiation from the poles is cool and the radiation from the equator is warm. On the opposite, form the equatorial regons, we have a rather cool radiation, at least form the areas where we have rain forests. The intensive exergy consumption done by the equatorial ecosystems actually cools the area (and that is not only by the strong evaporation in the area).
This is something that also happens in the small scale. Do you want to tell if a flower in a pot is a real flower or an almost perfect model, made of plastic? Hold a leaf between your fingers. The living leaf is cooler than room temperature, while the plastic leaf has the same temperature as room temperature.
For the living ecosystems, it is the same. The more mature it is, the cooler it is.

So, when we destroy the rain forest, issues of biodiversity, medicine, beauty, native population are often brought to discussion. The very important issue of global cooling is often neglected. In principle, one can say that the more mature an ecosystem is, the cooler it is, and the more counter-impact it has on global warming.

If you can read Swedish, a longer discussion on this is available.