Earlier quoted context omitted.
What are poor arguments about overpopulation? Clearly overpopulation is part of the problem.
Is it? When countries modernize their economies, the birth rate plummets to near-replacement rates over the course of about two generations. Take Iran, for example. In 1980, their birthrate was around 6. Today, it's lower than Europe. What population growth we're seeing today is mostly due to increased lifespan, not high birth rates.
The theory that growth slows with economic improvements is nice, but it is not a law of nature. Besides even with no more growth, we still have billions of people who want to raise their lifestyle to Western levels, increasing their CO2 footprint by orders of magnitude.
And another way to look at it: if there were only 10000 humans on earth, they would probably have a difficult time trying to move CO2 levels by a significant amount, or producing significant amounts of plastic, and so on. So clearly population size is a part of the problem.