Reducing population is about as popular as atheism. We are a shockingly self-centered species which is why we have a God-construct who created us in His image. How absurd. Most people have kids because they live on autopilot & are fulfilling a biological function. Not having kids because the planet is dying is about as likely as not driving a car because the planet is dying. We have a firm and abiding belief in our free will that is deeply wrong. Most people, most of the time, make decisions based on emotion, not intelligence.