>to consider support for candidates that at least acknowledge that there is a problem
There are none. Every candidate for every major party in almost all western nations is openly pro-growth. Saying "we'll tax CO2 emissions while importing millions of people and destroying ever more of the little remaining natural ecosystems on the planet" is not acknowledging the problem: overpopulation.
>Consider a carbon tax.
That won't do anything. CO2 is not the problem, too many people is.
>Consider sexual education efforts in developing nations
That is at least addressing the issue, but it also gets you labelled an evil racist nazi klansman. Unfortunately it also hasn't proven effective. The governments of those countries need to be directly involved like China's one child policy.
>There's a ton of things we can do, but we have to start doing
We're still doing in the wrong direction. The population of Africa has increased by 1000% in the last century, and we're still actively trying to make that continue, while pretending we can simply import a tiny fraction of those people into Europe and North America as if that will solve anything.