It's an interesting theory, however there's a few issues involved...
For starters, the temperature drops about 3º F. per 1000' of elevation,
so anything about about 15,000 ft. is guaranteed to be pretty much
frozen.
Even worse is that the % of oxygen available drops the higher you go,
so any part of the tree that's 25,000 ft. or higher is going to be oxygen
starved. This is why mountain ranges have "tree lines", as the trees
don't grow above a certain elevation.