One thing to do is to consistently shout down voices who routinely fall back into the outdated "population growth is good because we need it for my comfortable

One thing to do is to consistently shout down voices who routinely fall back into the outdated "population growth is good because we need it for my comfortable pyramid-powered pension" argument, not realizing how much it is at odds with whatever environmentalist views they might also hold. And even if they are convinced "fuck the planetists": the old trick of deriving comfort from growth will stop working at one point, and the only open question is how close we are already or maybe even beyond.