> There is no global overpopulation problem over the next century

Sure there is. If the mere act of eating a staple food item causes so many carbon emissions it contributes to planetary-scale climate change, you have an overpopulation problem.

> If the mere act of eating a staple food item causes so many carbon emissions it contributes to planetary-scale climate change, you have an overpopulation problem.

That is incorrect. If there is one person who produces the same amount of carbon emissions, it's the same problem which is independent of population count. All resources to sustain life are going to dwindle and secondary effects will continue to amplify, regardless of humans exist at all, over a long enough period of time.

"Overpopulation" is used to define the set of problems (logistics of practical food/water production) that make climate change a secondary concern. Ofc, you can define it how you like to talk past other people.