A number of people have claimed that a full-scale nuclear war is likely to cause
human extinction. I have investigated this issue in depth and concluded that
even a full scale nuclear exchange is unlikely (<1%) to cause human extinction.

By a full-scale war, I mean a nuclear exchange between major world powers, such
as the US, Russia, and China, using the complete arsenals of each country. The
total number of warheads today (14,000) is significantly smaller than during the
height of the cold war (70,000). While extinction from nuclear war is unlikely
today, it may become more likely if significantly more warheads are deployed or
if designs of weapons change significantly.

There are three potential mechanisms of human extinction from nuclear war:

1) Kinetic destruction

2) Radiation

3) Climate alteration

Only 3) is remotely plausible with existing weapons, but let's go through them
all.

1) KINETIC DESTRUCTION
There simply aren't enough nuclear warheads to kill everyone directly with
kinetic force, and there…