I think you underestimate the effects, though causal proof is going to be lacking. (Can't prove, e.g., that this prediction isn't caused by overfishins.) Fish are dying out. So are all sea animals that depend on a calcium skeleton. This is because increased carbon dioxide dissolved in sea water makes it more energetically expensive to extract calcium for the skeleton from the sea water. So I'm also talking about corals. Jellyfish will do well. So will some small animal (you need a magnifying glass, but not a microscope) that use silicon skeletons. Sharks and rays may do alright, but may need to adapt their diet.
On land many plants will not be able to be grown where they have traditionally been grown, but others will do ok. Many plants will become lower in protein and higher in starches as carbohydrates become energetically easier to build. diseases never before heard of will spread from the tropics. Etc.
(N.B.: Some of these predictions are sure things, because they are already happening.) Weather patterns will become more irregular, causing both more dorughts and more floods, longer heat waves and longer cold spells...and in these last two longer often translates into more extreme. Lots of other effects, mainly small, mainly difficult to causally tie to climate change (i.e., global warming). But whose probability of occurance can be reasonably be believed to be increased by global warming. (Do note that this included cold spells.)