Does that include the increased risks of nuclear war, new disease vectors etc? Because, while the probable outcome is relatively little impact the butterfly effect means you can get some less predictable results indirectly.
Aka migration causes war X which due to _ spiraled into WWIII. Granted the world without global warming could alos end randomly as well so you can just say unknown unknowns are always a risk even if it does mean a slightly less stable geopolitical environment that does not nessisarily mean anything terrible happens.
you do realize that initiating nuclear war is suicide, right? the u.s. took advantage of the only chance of actually using one because they were the only nuclear power at the time.
you don't need to consider the entire set of humans, only those with the ability/drive to obtain enough power/influence to gain control over a nuclear weapon.
Aka migration causes war X which due to _ spiraled into WWIII. Granted the world without global warming could alos end randomly as well so you can just say unknown unknowns are always a risk even if it does mean a slightly less stable geopolitical environment that does not nessisarily mean anything terrible happens.