This was assessed by the Pentagon back in 2014 > https://web.archive.org/web/20141013222428/https://www.acq.osd.mil/ie/download/CCARprint.pdf https://web.archi

This was assessed by the Pentagon back in 2014 > https://web.archive.org/web/20141013222428/https://www.acq.osd.mil/ie/download/CCARprint.pdf https://web.archive.org/web/20141013222428/https://www.acq.o... And it's pretty straightforward: as water, arable land and other resources become scarcer, then groups facing severe shortages will fight over the leftover resources.