If you think that the human food supply will not be affected by a planet-wide ecosystem collapse, you might want to think again. Fertile soil is not just dirt.

If you think that the human food supply will not be affected by a planet-wide ecosystem collapse, you might want to think again. Fertile soil is not just dirt. Talk to a soil expert and you'll find out very quickly how difficult it is to keep soil healthy, especially if you punish it every day with pesticides and herbicides. See you long you can maintain production if you don't have a support system of insects, arachnids, worms, fungi and so on. You'll end up with just dirt. Nothing grows in just dirt. You can try to keep up production by downing it in fertilizer, but in the end you'll just prolong the inevitable; loss of crop and collaps of production. See how many humans you can feed by growing crops in space stations. See how long you can maintain a closed ecosystem in space. To your last point; if you lose more than 30% to 30% of the productive workforce, you can kiss human civilization goodbye; our manufacturing is highly de-centralized, but heavily interdependent and without safety buffer.. Our infrastructure is wide-spread and needs tons of maintenance. Lose enough people and it all comes crashing down, leaving the survivors with broken machinery for which they don't have energy, don't have the knowledge to operate let alone repair if (not when) they stop working. They will also have to deal with all the poison and radioactive fallout from all the fission reactors that experience core-meltdown because nobody's around anymore to power them down over the period of ten years. Don't kid yourself; saving what's left of this earth's ecosystem is the only shot we have. There's not techo-utopia down the road to carry us to eternity and the heat-death of the universe. Its you and me and the rest of us puny humans that will have to do the saving.