if we continue to switch to renewables we will soften the hard edge of climate change and it can be enough for humans to adapt. i think there's a good chance we can watch it unfold while growing old and a lot will change, but it can be okay and humans won't suddenly go extinct or live in mad max conditions.
it's more likely humans will be forced to live most of their life in protective structures and nature will adapt with new species genetically suited for the new climatic conditions. weird plants and crazy animals.