If we truly can just plant 1T trees and solve the climate change problem, then I am fully 100% on-board with getting it done.
I've been a huge fan of bamboo once I heard about its properties compared to wood: It uses less water and it takes less time to grow, all while retaining the strength and texture of wood. I'm also a huge fan of meat alternatives such as Impossible Foods' plant-based "meats."
Both of these things, theoretically, should reduce the costs of what they replace. Growing a cow from birth to eating-age is expensive. Growing a tree from seed to logging-age is expensive. I think that if the concern about solving climate change is cost and the solution is more trees, then there's a possibility that the solution to climate change will actually save us money.
Growing a cow for meat consumption requires a lot of space. Space that can be used for trees. Using wood instead of bamboo obviously reduces the tree count. Trees that could be better used to, allegedly, solve climate change. If we can reduce the amount of farmland the amount of wood consumption in the world I wonder if we can get closer to 1 trillion trees.