From the January Scientific American:

Twenty-five years ago international teams of scientists showed that a nuclear war between the U.S. and the Soviet Union could produce a “nuclear winter.” … killing plants worldwide and eliminating our food supply. … International discussion about this prediction … forced the leaders of the two superpowers to confront the possibility that their arms race endangered not just themselves but the entire human race. Countries large and small demanded disarmament. Nuclear winter became an important factor in ending the nuclear arms race. … Gorbachev observed, “the knowledge of [nuclear winter] was a great stimulus … to act.”

Why discuss this topic now that the cold war has ended? Because as other nations continue to acquire nuclear weapons, smaller, regional nuclear wars could create a similar global catastrophe.  New analyses reveal that a conflict between India and Pakistan, for example, in which 100 nuclear bombs were dropped … would produce enough smoke to cripple global agriculture. … Not only were the ideas of the 1980s correct but the effects would last for at least 10 years, much longer than previously thought. …

More than 20 million people in the two countries could die from the blasts, fires and radioactivity. … A nuclear war could trigger declines in yield nearly everywhere at once. … Around one billion people worldwide who now live on marginal food supplies would be directly threatened with starvation by a nuclear war between India and Pakistan or between other regional nuclear powers.

Furthermore:

The effects of a war involving the entire current global nuclear arsenal … [include] a global average surface cooling of –7°C to –8°C persists for years, and after a decade the cooling is still –4°C (Fig. 2).  … Cooling of more than –20°C occurs over large areas of North America and of more than –30°C over much of Eurasia, including all agricultural regions.

So, the first news about nuclear winter was shocking enough to induce cold war adversaries to agree to big cuts.  Today we know the situation is even worse – not only is nuclear winter easier than we thought to trigger, but more nations now have big enough arsenals to trigger it.  Yet today there is far less international discussion or momentum to prevent such disaster.  Why the difference?

Perhaps what triggered Western citizen interest last time was not so much that disaster loomed, but that disaster seemed attributable to our moral failings – to our being too belligerent.  This time, we don’t feel so belligerent to Russia, and other wars seems like someone else’s fault.  Perhaps we care less about anticipating and avoiding disasters, and more about avoiding moral blame for whatever does happen.

Many huge problems loom on a century or so timescale, but the only one that penetrates our public consciousness is global warming.  I suspect that is because people see it as attributable to a moral failing of theirs, something like greed, gluttony, or insensitivity to nature.  If global warming were just as serious a problem, but caused by an inhuman geological process, I suspect it would get a lot less attention.

If you want the West to attend to a looming future disaster, it seems you must blame it on their current immorality.  The disaster I fear most is an unanticipated em transition; how can we blame that on a current moral failing?  Imprudence is a moral failing of sorts, but alas it ranks low as a dreamtime concern.