If over one year everyone planted 3 trees per week, and we employed a work force of people to cultivate them further, we would make a huge dent in our catastrophic risk exposure? Sure, it's seemingly impractical alongside the status quo of land distribution and use ( $$$ into develop all the land and farm humans for rent!!), but... more green will be good for the health of nearly all the living things on Earth, and at the very least give us more time to find even better solutions.