We know that if you cut forests on land, the main problems will be the global warming t, the lack of natural air purifiers, and the smok and co2 contamination will increase.
I comment from my own experience.
I have varied farms in the tropics, where there are jungle forests.
There were parts of my farm where there were a lot of trees, and in order to work I had to cut several. (60hect)
Before doing it the terrain was humid, almost the sunlight did not touch the ground, it was sometimes dark inside the forest.
When cutting the forest, the temperature of the sun increased, it was almost impossible to be there at noon. Each time it gets hotter and the soil moisture disappears.
Sometimes the human being to earn a few dollars seems to destroy nature.
My farm is small but imagine the amount of trees that set cut down around the world.
The lands that were fertile will no longer be soon.
One of the problems is the excess of population and the indiscriminate printing of dollars.
If there were fewer people in the world, fewer resources would be demanded.
In conclusion, the world would be hotter and drier and polluted, but the human being would evolve.