The current IPCC estimate for say crop yields change is quite low, less than 10% for <2.4C warming [1]. What they miss out are the actual higher-order effects. Food shortages are already leading to export bans, for example by India with corresponding global effects [2]. And as the situation worsens, the dark political forces that will emerge will cause the real problems. Tit-for-tat export bans of food can cause 10% food shortage to famine in certain areas, to war and other sorts of conflicts. Self-imposed breakdown of global supply chains can be catastrophic
IPCC and climate scientists cannot do a game theoretic analysis of how countries will behave. The real danger lies, where as expected, everyone defects.
[1] https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6... Page 16
[2] https://www.aljazeera.com/economy/2023/8/16/how-indias-ban-o...