One more thing came to my mind, as OP has pointed that some areas might become colder. If the climate is really getting hotter due to global warming it shouldn't be a problem if trees would make it colder, am I right? Also, do we really need deserts? If some of them became a bit colder thanks too trees and possibly a bit more moist, it wouldn't be so bad, especially when we think of the entire globe. It might make deserts more habitable.
You do know, I hope, that deserts are complete ecosystems?
Here in the USA we have created pretty nice cities right in the middle of deserts. I can think of at least three examples, Palm Springs, Las Vegas, Tuscon.
IIRC it was the widespread use of air-conditioning in homes that made this possible.
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and then the deepness of the earth vegetal "crust" or layer is reduced... what they call canopy... a soy field is very small (height wise).
I'm not sure about a precise definition of earth's "vegetal crust" but you are wrong there. For a tree, the woody parts are essentially dead tubes, except for the inner bark layer. The green at the top is what's of interest, and if one stripped that and weighed it, would it weight more or less than a soy field?