Exactly what history shows this? Every major case of social change I can think of (civil rights, women's rights, labor rights, what environmental regulations we have) has happened through mass movements not independent individual choices.
The time is for collective action on this. @GretaThunberg has been quite articulate about the need for immediate systemic change not just personal choices. Also, great news today, thanks to action on the part of @sunrisemvmt CNN will host a climate-focused Democratic primary debate. Movements can change what is "possible".
There's only one solution that is known to be practical and based on non speculative approaches: nuclear fission power. And we have to do it globally. Even if emissions in the West drop to zero yesterday, it won't matter.