Earth's sixth mass extinction is already happening — and it is rapidly accelerating, researchers warned in a study out this week in the Proceedings of the National Academy of Sciences (PNAS) journal.
I mean, it's kind of inevitable. According to the stats on this page the total biomass of our livestock is 3.9% of all animal biomass, the total biomass of humans specifically is 2.3% of all animal biomass, and all wild mammals is only 0.3% of the biomass (with all wild birds accounting for a further 0.1%).
According to this article 38% of Earth's land area is used for agriculture. The remaining 62% is presumably generally among the less fertile sorts of land - mountains, deserts, etc.
It's not even a question of climate change. We've reduced the total volume of non-human-centric biomass on Earth, replacing much of it with a monoculture of our highly successful species and its domesticated associates. We've also spread around some hangers-on, like rats, that have filled a lot of niches that used to be occupied by more diverse local species. The remaining biomass simply cannot sustain as many species any more.
The only way to stop or reverse this trend would be to reduce the human population and increase its agricultural efficiency. Fortunately, that is possible. But only through continuing advancement of our technology and standard of living.
It's already happening. UN projections for population growth predict a population peak just shy of 11 billion in 2100, after which there's a slow decline. Things like vertical farming and cultured meat or meat substitutes should eventually be able to produce food more cheaply than conventional farming does. We just have to continue working on stuff we're already working on.
The source I dug up while writing that comment said 10.9 billion, but since these are projections they vary a bit depending on the assumptions that go into them. The important underlying point is that the line eventually goes back down again.