I expect Clark is right. The nub will be convincing German voters that they should not want more stuff.
If all reasonably well off people refused to fly to other countries. If they kept the same cooker for twenty years. If they kept the same cycle for twenty years. If the demanded that their food was not coated in plastic. If they stopped keeping cats and dogs. If they stopped buying stuff from Asia but instead made stuff at home, so the item only travelled a few miles from the manufacturer to the buyer. If people mended stuff we it broke, rather than just buy new from Asia.
A lot of ifs. Clack is correct that ecological collapse is happening, now. What we seem to be not agreeing on is the cause. I doubt all ecological collapse is just because of burning fossil fuels. That is a part of the problem but it is not the nub of the problem. The nub of the problem in the increase in human numbers and the destruction of habitat that then ensues. Just concentrating on fossil fuels is doing us a disservice, it is missing the main target.