My favorite expert on population:
I was just about to post a video by him. He did make a compelling argument that we will stabilize at around 10 billion because as child mortality rates drop, women tend to only have about 2 children each. It's a little above and a little below per country, but it's very close to 2 each.
The problem with this is that of the about 7 billion on the planet right now, about 4 billion are under 30 and those people are going to grow older and have 2 children per woman. That makes the older cohorts bigger until each cohort is around 2 billion each and the world population is about 10 billion.
I don't think the world can sustain more than about 2 billion long term. Maybe a little more, but while 7 billion is doable for a bit, I think we're stripping resources too quickly to sustain it indefinitely.
The don't worry, be happy crowd on population growth think we'll solve all the problems caused by that many people and everything will be fine, but we've lost a lot of ecosystem already trying to give all those extra people a place to live. Madagascar used to be almost all jungle. That's been stripped bare now by an expanding population. There are little pockets of jungle left for what remains of the biodiversity the island used to have. Fishermen are stripping the waters around the island bare to feed the population.
Similar things have happened to Brazil and a number of other tropical countries.
People focus on how much CO2 we're putting into the atmosphere, but too little attention is being paid to the destruction of CO2 sinks around the world. Something has been killing plankton in the oceans, probably due to something we have done to throw off the balance (plastics, agricultural run off, over fishing?) and we've taken down large swaths of jungle.
People in the first world are panicked about plastic straws and other plastic one use items. We do over use them, but 90% of the plastic floating in the oceans come from a handful of rivers, all in Asia or Africa. I don't believe any developed country dumps their trash in the ocean anymore. In a lot of developing countries many rivers have turned into the sewers and waste disposal sites. All that garbage ends up in the oceans eventually.