A side event at the UN climate change conference now underway in Paris (COP21
) urged a new, easier-to-understand way to discuss trees and climate change mitigation: Rainfall.
Rainfall made through evapotranspiration from plant matter cools
the air around, since plants use heat energy to release water into the atmosphere. And a tree is more cooling than short vegetation; it uses 100–200 mm more water per year.
But the story is much more interesting, thanks to air currents that transport moisture from one place to another.