For most people, “climate change” conjures up images of fires, floods, severe wind damage and humans suffering from extreme storms, long droughts, sea level rise and heat waves as the air and oceans warm up and glaciers melt.
But for physicists who have been modeling the potential environmental impacts of a nuclear war since the early 1980s, humans could cause climate change triggered by temperatures running in the reverse direction — an instant Ice Age lasting more than a decade. Temperatures would plummet below freezing most days. The predicted result: food crops would fail and massive starvation would kill millions of people who survived the blast effects and radioactivity of nuclear bomb explosions.
In his recent virtual talk on the climatic and humanitarian impacts of nuclear war to Friends of Oak Ridge National Laboratory, Alan Robock explained the “nuclear winter” theory. The distinguished professor of climate science in the Department of Environmental Sciences at Rutgers University said the phrase nuclear winter was coined in a 1983 Science magazine paper coauthored by Carl Sagan, the famous astronomer and science communicator. The phrase describes a phenomenon first predicted in 1982 by two scientists in a Swedish journal article, “Nuclear War: The Aftermath.”
“Paul Crutzen and John Birks were the first to point out that there will be massive fires and that the smoke from the fires could change climate,” Robock said. He then showed an illustration of Earth’s Northern Hemisphere covered by a cloud of smoke that moved south.
“The smoke comes from fires that would be started by detonated nuclear weapons,” he said. “If there was enough smoke to block the sun’s heat and light, the temperatures would plunge below freezing even in the summertime. We call that nuclear winter. It would be cold, dry and dark. The heating of the stratosphere would destroy the ozone layer so more ultraviolet radiation would reach the surface. Food crops would die, causing global famine
Robock’s 1984 paper in the scientific journal Nature indicated that a nuclear war would produce higher-than-normal amounts of sunlight-reflecting ice and snow, making Earth even colder.
He surmised that his paper and the papers of American and Russian scientists doing climate modeling may have halted the arms race between 1986 and 1993, based on statements citing scientists’ conclusions by former American and Soviet Union presidents Ronald Reagan and Mikhail Gorbachev.
But, Robock said, “We still have 10,000 nuclear weapons deployed and over 13,000 weapons on the planet (down from 70,000 in 1986). Nine nations possess nuclear weapons, but the U.S. and Russia have 90% of them.”
The superpowers have about 6,000 warheads each, he added, “but the other seven have only a few hundred or fewer than a hundred each. The problem has not been solved.”
He and others have been involved in modeling the climate and crop impacts of millions of tons of smoke injected into the upper atmosphere by a regional nuclear war between India and Pakistan and a larger nuclear war between Russia and the United States. Here is his conclusion:
“A nuclear war between any nuclear states, using much less than one percent of the current nuclear arsenal, would produce climate change unprecedented in human history. A small nuclear war could reduce food production by 10 to 40 percent for a decade, with massive increases in ultraviolet radiation (which causes deadly skin cancers).
“The current arsenal can still produce nuclear winter, causing global famine and killing millions of people. In a U.S.-Russia nuclear war, more people could die in India or China than in the U.S. or Russia even if no bombs were dropped in India or China. The effects of regional or global nuclear war would last for more than a decade.”
Robock, a member of the Physicists Coalition for Nuclear Threat Reduction, has spoken to a number of university physics departments to encourage physicists to advocate to Congress and stakeholders that nuclear weapons should be eliminated.
“We are lucky that for the past 75 years there has not been a second nuclear war,” he said. “Here are the immediate steps we can take to make this less likely. Take U.S. land-based missiles off hair trigger alert. Give up granting the U.S. president the sole authority to launch nuclear weapons. Change our nuclear policy to one of ‘no first use of nuclear weapons.’ Stand down our land-based missiles and begin to dismantle them as part of a rapid reduction of our nuclear arsenal.”
Robock provided evidence that nuclear arsenals do not deter conventional weapon attacks by non-nuclear states and terrorist groups. He added that the world has been endangered by several “nuclear close calls,” including on “Black Saturday,” Oct. 27, 1962, during the Cuban missile crisis when the U.S. and the Soviet Union came close to initiating nuclear attacks.
“A nuclear war could start tomorrow by accident, hackers, computer failure, bad sensors or unstable leaders,” Robock concluded. “The only way to prevent a global catastrophe is to get rid of nuclear weapons.”