[fractallyte]

Overpopulation - a number - is the wrong metric. Instead, we should be looking at the mix of factors (which include overpopulation) that cause the destruction of ecosystems, all the way up to climate change. So that would include: mono-agriculture ('monoculture'), technology powered by fossil fuels (such as logging machines, strip mining machines, etc.), and global transport networks (which hugely enable demand to outstrip supply).

More complicated, but more accurate - and humanity is way past that threshold, even with population crashes.