First, what exactly are humans destroying? The list is long: other humans, many other forms of life, whole ecosystems, forests, water systems, mountaintops, and social communities. We are critically impacting the ability of nature to balance itself and to sustain life, particularly large life forms. While what is known as the “world” will continue in the event that planet earth is still around after humans leave it, then yes there will be a planet, but it will be an ugly, toxic mess, a koyaanisqatsi nightmare from which we will never awaken. Of course, this world could be seen as an edenic mecca for other forms of life which would then thrive and evolve to become god knows what. I guess beauty and health are in the eye of the beholder, then, so why worry about it all, eh?
Secondly, the forest systems on this planet are crucial to keeping the atmosphere in balance and breathable. Not only that, but they serve to help keep CO2 levels down, along with the oceans, which are now stressed, turning acidic, and toxic to life. The consequences for deforestation and oceanic toxicity are proving horrendous and harbinger dire events in the future, notwithstanding the problems and harms occurring now. This is all just basic science, by the way, something neocon and crazed fundie politicians and economists do not like to deal with.
Thirdly, corporate farming practices do a lot of harm on more than one level. Pesticides we already know about. As for the GM seeds and foods, more is becoming known about their dangers and the problems they cause. Farmers are forced out of business because of GM seeds, which are designed to be obsolescent so that farmers will have to buy them from corporations every year, and not having the money to do that, then go out of business to be taken over by corporations and forced into virtual servitude and endless poverty. Also, farmers are forced to produce the same cash crops every year, which is bad for land and agriculture. And then, GM foods themselves are not good for humans. Some animals won’t touch them.
Organic natural farming and foods really is the best way to go. Free range meats and eggs, and natural pesticide and hormone free foods provide the only healthy alternatives in an otherwise toxic food environment.
Last, global warming is already becoming a significant problem. Ice melt and desertification are proceeding apace. Certain cycles are shifting so that some areas get more rain and others less; and storms and weather events are intensifying. Sea levels have begun to rise as islands are disappearing and some coastlines changing. As land mass decreases and populations shift, life is going to be very difficult for many many people. But I also think that this will occur as life support systems start to shut down as well, and I’m not sure whether this scenario has been investigated much or not.