Hans Morgenthau explains how the prospect of general nuclear war and the annihilation of civilization changes our experience of death. "Death in the Nuclear Age" (1961):

In the works of his mind, man, the creator, survives.

Yet why are those works a "monument more lasting than bronze," and why can their creator be confident that "on and on shall I grow, ever fresh with the glory of after time"? Because the man endowed with a creative mind knows himself to be a member in an unbroken chain emerging from the past and reaching into the future, which is made of the same stuff his mind is made of and, hence, is capable of participating in, and perpetuating, his mind's creation. He may be mortal, but humanity is not, and so he will be immortal in his works. ...

Man gives his life and death meaning by his ability to make himself and his works remembered after his death. Patroclus dies to be avenged by Achilles. Hector dies to be mourned by Priam. Yet if Patroclus, Hector, and all those who could remember them were killed simultaneously, what would become of the meaning of Patroclus's and Hector's death? Their lives and deaths would lose their meaning. They would die, not like men but like beasts, killed in the mass, and what would be remembered would be the quantity of the killed - six million, twenty million, fifty million - not the quality of one man's death as over against another's. Of their deeds, nothing would remain but the faint hope of remembrance in distant places. The very concept of fame would disappear, and the historians, the professional immortalizers, would have nothing to report. What had been preserved and created through the mind, will, and hands of man would be dissolved like man himself.

Having grown up with the threat of nuclear war - I was in high school in the early 1980s, when tensions in the Cold War were high - I find it easier to think about global warming with equanimity. Global warming is a terrible threat, but at least it's a slow-motion problem.