[hugh4]

> Today, we can kill everyone off with an exchange of the already existing nuclear weapon inventory

I'm not convinced we can. For starters, the nuclear weapon inventory is a lot smaller than it was back in the 80s when those sorts of statements were popular. And secondly, as I understand it, it was always a bit of a lie, an estimate based on some silly assumptions (e.g. that everybody in the world lives in cities), which in repetition eventually lost those assumptions.

And yes, I agree with the other poster that it's pretty much impossible to kill everyone on earth with climate change.

Species-ending diseases I do worry about, but maybe that just means I don't know as much about immunology as I do about nuclear weapons.

[Zigurd]

There are many fewer weapons available for an impromptu nuclear war, and despite the horror that I think many readers here underestimate, that reduction is a Very Good Thing. The problem is that the nuclear explosives may have been taken apart to some extent, but they can also be put back together.

The nuclear arsenal is predominantly hydrogen bombs, and they are insanely powerful. The Hiroshima bomb was 16 kilotons. A W-87 and W88 warheads are a bit under half a megaton, or roughly 30X more powerful. The W-78 is about 350kilotons, about 20X larger. The B-83 bomb lets you dial in just how spectacular you want a return to neolithic life to be, all the way up to 1.2 megatons, about 70X larger than the Hiroshima bomb. There are fewer than 250 cities with over 1M population. With just the ready US arsenal you could blanket most of the populated parts of the planet.

In 1967 the US maintained an arsenal of about 30,000 (!!!!!) nuclear weapons. You have to wonder. Now the stockpile is about 4500 and about 1500 are deployed and ready at a moment's notice.

[sehugg]

Recent research has shown that nuclear winter after even a limited exchange would be worse than previously thought. We don't know how/if our technological society would bounce back from N billion starvation deaths.

[stevetrewick]

Indeed, just 100 small warheads would (maybe) do it. See Mills' Multidecadal global cooling and unprecedented ozone loss following a regional nuclear conflict [0] which models the effects of a limited nuclear conflict between India and Pakistan.

[0] http://onlinelibrary.wiley.com/doi/10.1002/2013EF000205/full

[hoodoof]

The U.K., U.S. and Russia have already bombed the world with hundreds of atmospheric nuclear weapons in the mid 20th century.

In effect there was a nuclear war, it's just that all the bombs were exploded on "friendly territory" like Australia, the pacific islands and Nevada.

[D-Coder]

Atmospheric tests do not produce the same particulates as setting entire cities on fire.

[hoodoof]

So it was sort of OK "nuclear war on ourselves"?

[Teever]

I believe you misunderstand the cause of a nuclear winter.

The cause isn't the nuclear radiation per se. It is the extreme destruction of many large urban centres simultaneously. The problem is that all of those cities burning simultaneously would send up a tremendous amount of ash and smoke that would block the sky for quite a while.

This would cause a reduction in the amount of sunlight that would be available for growing crops and combined with the almost total destruction of global economy could result in the destruction of the entire human race through mass starvation.