I don't disagree with the diagnosis. Population + consumption = overshoot. The issue is, whether we want to reduce suffering. For me, a non-religious person who considers himself moral, increasing well-being and reducing suffering are the metrics to live by.

In order to reduce suffering, especially that which is bound to come in the near to mid term future as we pass these tipping points and experience collapse, we should be deploying every emergency stopgap measure we can.

Slowing the warming at the poles by a fraction of a degree could mean saving millions of lives, buying a little time to relocate people from the coasts, etc.

There's a bit too much darkness in the "we need less population" argument; it has too much in common with the "kill em all and let god sort em out" kind of thinking.

We need to slow population *growth* not let people (and thousands of species of other living things) die horrible deaths as treatment for the disease.