“The conventional bombs of World War II were called “blockbusters”, filled with 20 tons of TNT they could destroy a city block. All the bombs dropped on all the cities during World War II amounted to some 2 million tons of TNT — two megatons. Coventry, Rotterdam, Dresden and Tokyo — all the death that rained from the skies between 1939 and 1945 — a hundred thousand blockbusters, two megatons. Today, two megatons is the equivalent of a single thermonuclear bomb — one bomb with the destructive force of the second world war. But there are tens of thousands of nuclear weapons. The missile and bomber forces in the Soviet Union and United States have warheads aimed at over 15,000 designated targets. No place on the planet is safe.
The energy contained in these weapons — genies of death, patiently awaiting the rubbing of the lamps — totals far more than 10,000 megatons; but, with the destruction concentrated efficiently, not over six years but over a few hours. A blockbuster for every family on the planet; a World War II every second for the length of a lazy afternoon. The bomb dropped on Hiroshima killed 70,000 people. In a full nuclear exchange, in the paroxysm of global death, the equivalent of a million Hiroshimas would be dropped all over the world. And, in such an exchange not everyone would be killed by the blast and the fire storm and the immediate radiation. There would be other agonies. The loss of loved ones; the legions of the burned and blinded and mutilated; disease; plague; long-lived radiation poisoning the soil and the water; the threat of stillbirths and malformed children; and, the hopeless sense of a civilization destroyed for nothing. The knowledge that we could have prevented it and did nothing.”
- Carl Sagan; The Blessing and the Curse: Carl Sagan on Nuclear War, Colonizing Space | "Who Speaks For Earth?" (Cosmos: A Personal Voyage)