Total destruction of our ecosystem including us as a side effect of our desire to live a comfortable life is unavoidable, as the man says, many people will die as a result, eventually everybody.
How does the climate mass extinction work? Simple, the oceans will release their stored methane and be really dead. The oceans will run out of oxygen and start to produce large amounts of a poisonous gas called hydrogen sulfide. this will kill most life on land, plants and animals. This happened before at the end of the Permian era, initiating the biggest extrinction on record.
More on the oceans and what can be done about it here
Cooling has an immens positive effect on carbon absorbtion on land and in the ocean, but the only way to achieve that would be to have a nuclear war. Alternatively one could guarantee oxygen and nutrients for ocean life by using wave energie to it pump up from greater debt. That too is a battle because warming causes tratification, where the cold stays at the bottom and the warm at the top, locking in nutrients out of reach of the photozone.
As long as people believe they have to make money to pay thier mortgage it’s going to be oil/credit to the bitter end.