There are many natural ecosystems which could and would be severely disrupted as the food chains there break up.
However, the food chain for homo sapiens largely relies on artificial monocultures that can be moved around and replaced on a large scale if the local conditions change. Natural environment can't switch to a "warmer climate biome" overnight, but a farmer can and will plant an entirely different crop in the next season if that suits the place better now, with only some expenses in retooling tractor attachments. And while there are many food industries which are relatively brittle, these are relatively niche 'luxury' foods which often are economically very valuable, but not the staple foods which actually feed the population. Like, if California had to abandon growing almonds due to water issues and instead grow something less demanding (and less profitable), that would destroy a huge industry but wouldn't cause food insecurity.
As just one example, ocean acidification could kill a lot of the algae. Pretty much everything is upstream of algae. It would be catastrophic, even for us.