No, just no. You can't show that. You don't understand environmentalism. You're just a Malthusian. It's an assertion that human existence is incompatible with the environment, and that's a completely unacceptable proposition, because it defines "environmentalism" as "extinction."
Reducing the population by half will, at best, reduce emissions by half. That's not going to stop climate change. That's not climate action. That's not anything at all.
I really wish people with your attitude would study ecology, would study biology, would study the world. Life, human and not, all affects the ecosystem. All life depends on other life. We all interact, we all change the world. Life has fundamentally changed the geology of Earth in absolutely drastic ways! Life is impact. Defining environmental purity as the absence is an ideology bereft of life, and the nature of life.