A slight detour from the global warming discussion:
Just this morning my family was discussing how in 1816, almost every family was forced to leave our town and moved to the Midwest (which was less affected). It was “the year without a summer”.
1816 in rural New England meant a lot of subsistence farming. Mount Tambora in Indonesia erupted, putting so much dust into the sky that weather changed markedly, and crops failed. One source says 90,000 deaths globally attributed to the event.
Now that occurred at a time when people knew how to feed themselves, and the global population was much less.
I am guessing that at our current population density and inability to feed our families without grocery stores, it would be a big deal, but industrial farming from elsewhere in the globe would probably keep us afloat.
Unless we were also in the midst of some massive financial collapse or SHTF event, at which point we’d all be starving.
https://en.wikipedia.org/wiki/Year_Without_a_Summer