The vast majority of the 1st world has much cleaner air, soil and water than 50 years ago despite a massive increase in population thanks to technological advancements in pollution control and energy production. First world populations are healthier and living longer than ever before. First world populations are largely stable if not shrinking.
The developing 3rd world are rightfully very busy clawing their way to 1st world living conditions and will burn alot of carbon to get there. World poverty rates have plummeted in the past 30 years thanks to plentiful and cheap energy which is a GREAT THING for billions and billions of human beings and worth some short term damage to our ecosystem IMHO.
I suspect in less than 50 years most of the 3rd world will reach 1st world living status, world poverty will continue to decline and the earth's population will stabilize.
We can't be complacent and need to continue to work for non-carbon energy sources, but I think our overall future is bright.
The problems with population pressure is much worse than CO2 increases. If we could bring the developing world to developed status without increasing CO2, we would still be in trouble.
We are exhausting a lot of our farm land just trying to keep the poorest billion people in the world alive. The war in Ukraine is causing severe food insecurity for these people because Ukrainian grain is not making it to these countries.
The oceans are getting over fished by countries just trying to feed their people. Large factory ships now travel the oceans scooping up all fish in an area, leaving no breeding stock. Most of these ships are based in Asia. In the waters under the control of developed countries, the fisheries are managed and fish stocks are largely stable, but the coast guards of these countries are constantly chasing out factory fishing ships trying to poach fish.
We are currently stripping the world of natural resources to provide the richest ~2 billion with the things they want. If we expand that to the poorer 5 billion, there won't be enough resources to go around. I'm not just talking about oil, this applies to all agricultural products, all mined resources, and fresh water.
It is true that the world economy is based on an ever increasing population. It doesn't have to be. To manage a declining population we would have to change a number of social programs to still protect those who can't contribute to the economy, but keep many who are older and could participate in the economy.
Ultimately we would need to shutter facilities, and abandon towns as the population declined, but again that could be done in an orderly fashion.
Europe lost between 1/3 and 1/2 of its population due to the Black Death. There were a couple of generations of people who had severe PTSD from the experience and the shadow of it still exists in European countries and countries settled by Europeans. There were local collapses in some areas as populations died off, but Europe came roaring back from the experience and a number European countries ended up dominating the world on the back of the Renaissance that came from the population decline.
We just dodged a bullet that could have turned into the next Black Death. COVID was the worst disease outbreak we've seen in 100 years. Thanks to modern medicine we were able to keep the death toll more on par with the Spanish Flu, but it is a much more deadly disease than any flu.
It has now mutated into a much more contagious disease, but with milder symptoms. Pandemics usually go this route becoming more contagious and milder. But what if it had become more contagious and more deadly? The way it has mutated it could go that route, though past pandemic patterns say it probably won't.
A new disease could come along that is much more deadly and highly contagious. That could drop the world population quite suddenly like the Black Death did to Europe. The denser the population, the higher the risk for a pandemic virus evolving.
As the world gets more crowded, I think the odds of that happening go up. With more people traveling more extensively, a potential pandemic can spread very widely before most people realize it's there. That's what happened with COVID, it was in Europe before the world knew it existed.
