You know when we first started seeing growing populations and development of agriculture? When the climate started an exceptionally long stable period. Guess what’s going put of the window now? Planting for draught because that’s the “new normal” won’t get you far if the next year happens to be the wettest on record. Let alone that stronger storms than ever seen before aren’t exactly great for harvests either. And that’s just agriculture. Climate related disasters can wipe out key infrastructure, with unexpected consequences down the line (e.g. no car production because of a certain specific part of almost all cars comes from that one specific place). And then there’s the refugee problem on top of all that.
Glad you already learned this is probably nonsense. The wrong reasoning is very similar to much thought about overpopulation. The amount of people that makes for a place to be overpopulated is a function of how societies work and the technologies they have at hand. One extra issue there is that improvements in technology usually lead to population growth, so much progress gets cancelled out.