There are no guarantees existing r&d efforts will result in a technological savior within your time horizon. There is no master plan, society is comprised of a bunch of individual money-making efforts. if the medicine that cures whatever ails you isn't profitable, you are not going to survive. Nothing can exist unless it has a high profit potential vs risk, there are always easier ways to make money.

>we lived through the ice age

Humans, not necessarily you individually, can survive the worst end of the AGW prediction range over the next 75 years. Just don't be poor. Would you prefer to spend your time trying to survive in such an environment or in the temperate interglacial that coincided with the rise of technological human civilization.

>what you just think by 2050 we'll be sitting on our asses doing nothing to prevent a mass extinction?

Why not, doing nothing is easy. Was anything done to prevent mass extinctions over the preceding 30 years.