Even with the population stable, there won't be enough food as aquifers deplete and irrigation stops, as soils turn to sterile sand, floods, early and late frosts, high winds, and disrupted distribution, along with more expensive factory farming.
The actual peak food was in the 1990s to 2000s, a very rounded 'peak'. By mid century the food output will be about half of that for 6 billion people, or well under the sedentary starvation level with even distribution. Sure, people will fight for food and water, turn cannibal and even drink their own urine.
Wars increase, along with malnutrition and low immunity with diseases more fatal. The increasing heat itself will cause more hostility along with more crowding.
The death rate increases to greater than the birth rate, with a very steep population decline.
Starting before 2030 and finishing just after mid century, followed by thermal max effects.
Unless a 'natural' disaster precipitates an earlier crash. Perhaps early enough to bring down emissions 90%+ in the next decade.
I think Cascadia or the La Palma slide could easily ruin the USA and cause world depression and mass starvation. If Katla causes a volcanic winter, the same.
After 2030 will be too late for anything but a Yellowstone eruption to change it from the thermal max trajectory, and after around 2100, it will be too late for even that to stop GTE.
Ruin of the biosphere could also happen with a nuclear war well over nuclear winter size.
Major bad things will happen in the lives of those living in 15 years. The party will be over.