It's not just nuclear catastrophe that's being measured.
>"Midnight" has a deeper meaning to it besides the constant threat of war. There are various things taken into consideration when the scientists from The Bulletin of the Atomic Scientists decide what Midnight and "global catastrophe" really mean in a particular year. They might include "politics, energy, weapons, diplomacy, and climate science"
Even the worst projections of climate change are not "doomsday" events. Global nuclear Holocaust is doomsday. Extreme weather and displaced people is not doomsday. Which goes to exactly my point about the clock being used by politicized scientists.
Wikipedia says that the group setting the clock didn't meet during the Cuban Missile Crisis. It seems they publish the clock annually.
It seems entirely reasonable that we're in more danger now than at sampled points before/after the Crisis - after all, it proved that the US and the USSR could manage to not blow each other up. There are more nuclear-capable powers today headed by less sensible men.
Also: "Because, you see, the clock is not a gauge to register the ups and downs of the international power struggle; it is intended to reflect basic changes in the level of continuous danger in which mankind lives in the nuclear age, and will continue living, until society adjusts its basic attitudes and institutions to the challenges of science."