I never said that we should not aim for something like net-zero, what I have said is that it (net-zero) is not achievable - it is a slogan, a mantra. Now if they said a reduction of greenhouse gases of 75%, say, by 2050 I could go along with that. Then we can get on with reducing the total, the concentration. If we can begin to reduce the global population at the same time so much the better.
However, we will not be able to do it if we go to a population of 20bn - that's nonsense. The fairytale is that we can even go somewhere near there. How are we going to feed them? Where is the land coming from to grow all these GM crops? The fertilizers? What about the fresh water to irrigate them? Then we need the machinery to harvest them, factories to process them, transport...Oh look, its Little Red Riding hood and Hansel and Gretel racing over the sunlit uplands to help us.
I now ask where these extra 12bn humans, up from the 8bn of today, will live and what in and where? Will they be in mud huts, tents, mansions or 150 storey high rise blocks? And where will all the furniture and appliances and the energy to run them come from? What about water for cooking and hygiene? And what will the residents be doing? Playing bowls and dominoes and watching TV or will they want work in order to buy things and pay the rent? What work? Hopefully nothing too damaging to the environments - what's left of them. Oh, hang on, bots will be doing all the work...
The people will also need clothing... We are already short of natural fibres such as cotton, jute, flax, hemp, coir from plants, and wool, hair and silk from animals as well a skins and hides. With all this land being used for food there will not be much left for producing clothing. So it will probably be more polyester, acrylic and nylon from.... oil. Ah, but we will have turned that off, oh well, there are plenty of plastic bottles to recycle if we have not just dumped them. Plastic clothing and furnishings - use once, throw in the sea or landfill, along with the plastic food trays, pots and bottles.
Then the seas will need cleaning up - constantly, not just once. Saying it will be a one-off $10bn job is absolute nonsense. In 2020 it was estimated that the initial cost would be $150bn with unknown ongoing running costs, and that is the "today" problem. Since that time hardly any investment has been made and little has been done. Even this might be an
underestimate. but not as bad as your $10bn fantasy when there are 20bn of us.
Have a nice future y'all.