Mainly those that are already having trouble feeding their populations. For example in Africa and Middle-East many countries are in trouble with the effects of the Russian invasion. I can only imagine what will happen in these parts of the world if climate change really starts to disrupt farming.

Of course this is just one way to look at the issue. If we look at resource consumption then worst offenders are elsewhere. After all, even current population levels could be sustained if nobody consumed more than the minimum they really need, food was distributed equally and green energy was dominant.