There is also the fact that the Amazon was intensively farmed which has resulted in the incredibly fertile soil found there; terra preta. Admittedly it would have been green but with crops not trees.
My view is that we started on the technology route a long time ago (fire, cultivation, cities and especially the industrial revolution) and it is now too late to find an alternative without drastic cuts in population. The only route out, if there is one, is to continue on that path.
Controlling the population is desirable but politically difficult. Reducing pollutants on the Earth; and there are/may be technological solution to that, but also expanding into the solar system. There is 24/7 free energy out there, plenty of raw materials and low or zero gravity environments which can aid manufacture. The issue is getting there and getting products back without causing more problems. If that can be done with less environmental impact and cost than for instance flying beans from Egypt to the UK then even some food production could be achieved as well as heavy and polluting industrial processes.
Think, space elevators, O’Neill cylinders, asteroid mining, lunar bases. But don’t listen to me, look at the science.
Of course all this is beyond the imagination or limited time span of any political thought and way beyond people who chuck soup at paintings. The best hope, for all their faults lies with visionary private enterprise seeing that there is money in that there emptiness.