Preventing unwanted pregnancies is a cost-effective and ethical way to reduce environmental destruction and minimize population growth, and 45% of pregnancies in the U.S. are unintended. Of those, 58% will result in birth. Comprehensive sex education would go a long way, too, and many states do not include it in their curricula, even though comprehensive sex education has strong bipartisan support among likely American voters. Many women at high risk of unintended pregnancy are unaware of long-acting reversible contraceptive options, and many men don't know how to use a condom properly, which does actually make a huge difference. Besides that, it could help to ensure everyone has access to effective contraception, so consider advocating policies that improve accessibility of long-acting reversible contraceptives and help get the word out that it is ethical to give young, single, childless women surgical sterilization if that is what they want.

As for the rest of the world, it would help to donate to girls' education. It might also (perhaps counter-intuitively) help to improve childhood mortality by, say, donating to the Against Malaria Foundation.

All that said, population is not the most significant cause of climate change -- it's the market failure. That's why the single most impactful climate mitigation policy is a price on carbon, and the most impact you as an individual can have is to volunteer to create the political will to get it passed.

And returning the revenue from a carbon tax as an equitable dividend would help a little bit with inequality, while creating jobs and growing the economy.

Taxing carbon is in each nation's own best interest, and the IPCC makes clear carbon pricing is necessary.

Policy changes absolutely dwarf the magnitude of the impact of having one less child.

How do you significantly decrease the population without committing mass genocides and other evils?

Ok, Thanos.

What is the "bright line" that defines overpopulation? Capitalism creates a false sense of overpopulation, when the real issue is that resources are not adequately distributed because it's not profitable.

If trillions of dollars weren't currently being used as a dragon's hoard we could easily live on this planet with enough for all and little impact on the environment.

Uhm... what? Climate change won't wipe out humanity, no matter how bad it gets, but hundreds of millions of people are at risk of suffering a lot from it, particularly in impoverished nations due to drought causing deadly heat waves, food, and water shortages etc. but according to you that is good because then we have reduced the population?

Overconsumption is the problem, not overpopulation. As long as unrestricted capitalism reigns supreme this won't end.

Ww3 is coming that'll get the population down. Add another pandemic and the plan is in place