Hiroshima + 70

August 6, 1945: I was 18 years old, 7 weeks short of my 19th birthday, a second year medical student, first-year physics fresh in my memory: I understood atomic physics. At the time my main emotion was relief that the war would soon be over. The full horror came a few days later with newsreels and photos of the devastation of Hiroshima and of survivors with horrible burns. The horror was accentuated when the New Yorker devoted an entire issue to John Hersey's article on Hiroshima on August 31, 1946. Our world changed forever on August 6, 1945. Seventy years later I still feel horror.

The two atomic bombs used in war were dropped by the Americans on Hiroshima on August 6 1945 and on Nagasaki on August 8 on the orders of President Harry Truman. The ethics and morality of Truman's decision to use atomic weapons have been much debated. The immediate devastation and huge numbers of casualties were unprecedented; delayed mortality caused by exposure to lethal levels of nuclear radiation pushed the numbers killed by those two small bombs to over a quarter million. 

Since 1945 the power of nuclear weapons has been immensely enhanced: the Hiroshima and Nagasaki bombs had explosive forces measuring a few kilotons. The average nuclear weapon nowadays has an explosive force measured in multiple hundreds of megatons. One well-placed modern nuclear bomb could destroy the entire megalopolis of Bos-Wash, the cities of Boston, New York and Washington and all the other cities large and small in that densely settled north-east corner of the USA. Montreal, Toronto and Ottawa are near enough to suffer some physical destruction as well as casualties. Many deaths would be slow but just as lethal, caused by exposure to fatal levels of ionizing radiation. A widespread nuclear war, probably even a regional nuclear war such as might break out between India and Pakistan, would cause a 'nuclear winter' - a sudden sharp decline in solar radiation reaching the earth's surface, because the massive amounts of dust and smoke in the air would occlude sunlight. It could take several years for this effect to subside, so a new ice age would be likely. The astrophysicist Carl Sagan developed theoretical models of this phenomenon. It alone would cause mass extinction of many plant and animal species, as well as massive famines due to crop failures.

The world has come quite close to a nuclear holocaust several times since 1945, although fortunately the hotheads have always stepped back from the brink in time. I fear a trigger-happy Israel more than North Korea but that's just a personal bias based as much on the combination of Israeli paranoia about Iran and the probable size of the Israeli nuclear arsenal as on the likelihood that North Korea has only one or two atomic bombs rather than a large arsenal of weapons as the Israelis are reputed to possess. The way armed conflicts have evolved since 1945 has been almost in the opposite direction from confrontation between great powers like USA and the former USSR.  Now the world is afflicted mainly with so-called low-intensity conflicts and unconventional warfare, such as the long-running wars in Central Africa and the former Belgian Congo, Burma, Colombia, etc. And, of course, the much more ominous low-intensity war being waged by the Islamic State in Iraq and Syria. Pakistan has nuclear weapons and another scenario to be greatly feared is a takeover of Pakistan by ISIS: if ISIS gained possession of nuclear weapons the probability of a nuclear war between ISIS and Israel would be greatly increased. 

That's more than enough gloom and doom for this pleasant summer morning.