nuclear-news

The Nuclear-Winter Debate

Jill Lepore’s article about the history of climate science and nuclear-winter theory is important, but her story is incomplete (“Autumn of the Atom,” January 30th). Although Lepore states that the nuclear-winter debate has “long since been forgotten,” research done in the past ten years, using modern climate models, has shown that the theory of nuclear winter—which says that smoke from fires started by nuclear detonation will block sunlight, causing the Earth to become drastically colder—was correct. Lepore also refers to Stephen Schneider’s alternate theory of nuclear “autumn,” from the nineteen-eighties, as if it refuted the nuclear-winter theory. But it failed to take into account the Earth’s stratosphere, was never published in a scientific journal, and was certainly not accepted by the scientific community. It was, however, used by supporters of nuclear weapons to try to discredit nuclear winter.

Despite the over-all decrease in Russia and the U.S.’s nuclear arsenals, the two countries still have the capability to produce a nuclear winter: a nuclear war that used less than one per cent of the current global arsenal would cause a climate change unprecedented in recorded human history. Let us hope that this summer’s U.N. negotiations to ban nuclear weapons will make it clear that a nation threatening retaliation or a first strike would be acting as a suicide bomber.

Alan Robock, Rutgers University

New Brunswick, N.J.

Lepore has done history and science, your readers, and my late husband, Carl Sagan, a great disservice. Her article’s central thesis demeans Carl’s scientific acumen and his character, wrongly asserting that, in his “grandiosity,” he harmed the environmental movement by advancing an exaggerated theory of the long-term consequences of nuclear war.

From Lepore’s account, readers would conclude that Carl’s interest in the greenhouse effect on Venus was something that he picked up from a bright grad student. In fact, five years earlier, Carl had published his own dissertation, viewed as the beginning of our modern understanding of Venus, which included his groundbreaking greenhouse model.

Lepore also gives the impression that the theory of nuclear winter has been debunked. If anything, more recent scientific research indicates that Carl and his colleagues were conservative in their estimates. Tellingly, she makes no reference to the findings—in peer-reviewed, refereed publications—that fully support, and expand on, the models created by Carl and the other nuclear-winter scientists.

Carl is also faulted for “partisanship,” in part for declining an invitation to dine with the Reagans in the White House—a choice that I made, in response to the El Mozote massacre and other crimes in Central America for which I believed Reagan bore some responsibility. Does Lepore find those public figures and celebrities who refuse to be co-opted by the Trump White House to be partisan? Or is that an unwillingness to lend your cachet to policies that you abhor?

According to Lepore, Sagan “made some poor decisions” and “undermined environmental science.” She leaves the reader to wonder what those bad decisions were. Fighting for the reduction of tens of thousands of nuclear weapons? Sounding the alarm on global warming decades before others started paying attention to it? Mounting the world’s most successful campaign for public scientific literacy? Attracting multitudes to science and reason? Turning the camera on Voyager 1, which was out by Neptune, to point homeward, to make us see our true circumstances in the vastness? What better decisions have other people made?

Ann Druyan

Ithaca, N.Y.

J Lepore article on the New Yorker from the 30 January 2017 http://www.newyorker.com/magazine/2017/01/30/the-atomic-origins-of-climate-science

Paper posted at Harvard by J Lepore http://scholar.harvard.edu/jlepore/publications/autumn-atom-how-arguments-about-nuclear-weapons-shaped-climate-change-debate