[asdff]

Exactly, carrying capacity of the land has changed thanks to how much of the biomass we are able to take advantage of. You don't get 8 billion humans on earth plus the abundance of flora and fauna from premodern times for free, its gotta come from somewhere and in this case we scorched a lot of the earth and disrupted a lot of flora and fauna for the agriculture that feeds 8 billion.

What changes the equation a little bit though is when we mine or extract resources like fertilizers and oil from below the surface of the planet. That is now adding nutrients and more energy to the system that wasn't around at least in premodern times. All that oil is old biomass anyhow, so burning it and adding it back to the atmosphere would potentially make it available again for species that take advantage of carbon fixation, if we give these species room to accumulate this biomass out of the atmosphere.

It's kind of interesting to think about how even with today's combustion engine tech, we could solve our climate change crises and set the earth to whatever greenhouse gas level we'd like, if we merely strove to balance this system by growing out sufficient biomass.