Populationism misses the root cause of geo-ecological destruction -- which is the capitalist mode of production. But Western environmentalism and its analytical categories (a la Ehrlich) is not the only way to understand the apocalypse -- or respond to it. 

There is, instead, the analysis from social ecology:

"The importance of viewing demography in social terms becomes even more apparent when we ask: would the grow-or-die economy called capitalism really cease to plunder the planet even if the world’s population were reduced to a tenth of its present numbers? Would lumber companies, mining concerns, oil cartels, and agribusiness render redwood and Douglas fir forests safer for grizzly bears if — given capitalism’s need to accumulate and produce for their own sake — California’s population were reduced to one million people?

"The answer to these questions is a categorical no. Vast bison herds were exerminated on the western plains long before the plains were settled by farmers or used extensively by ranchers — indeed, when the American population barely exceeded some sixty million people. These great herds were not crowded out by human settlements, least of all by excessive population. We have yet to answer what constitutes the 'carrying capacity' of the planet, just as we lack any certainty, given the present predatory economy, of what constitutes a strictly numerical balance between reduced human numbers and a given ecological area."

Murray Bookchin, "The Population Myth": https://theanarchistlibrary.org/library/murray-bookchin-the-population-myth