What evidence are you basing that on?
A new problem is discovered (i.e. the earth can't sustain the current birth rate forever). The problem is hyped up[1] in an effort to find a solution (abortions -> Zero Population Growth[2]). Many in the science community buy into the hype, crunch numbers, and make dire predictions. Public policies in the 70s change in response to this evidence. ZP deniers are shamed for having large families and rejecting scientific consensus. Decades pass and the predictions don't happen. People start examining the evidence with more scrutiny and with observed data in hand retroactively debunk a lot of the assumptions made. The hype dies and everyone forgets it ever happened. So I'm sorry if I don't instantly drop everything to make the hype of the day my top priority, but a lot of hyped problems don't last more than a few decades. If climate change is still being seriously discussed in 2036 (30 years after "An Inconvenient Truth" was published) maybe I'll take it a little more seriously.
In the meantime, other factors will contribute to our downfall much faster than climate change ever could such as increasing societal divisiveness over politics, decline in nuclear families as the basic societal unit, selfishness, and abandonment of religion.