X-Events by John L. Casti

Author:John L. Casti
Language: eng
Format: epub
Publisher: HarperCollins
Published: 2012-03-15T00:00:00+00:00

These are the main steps on the road to nuclear winter. Can we really expect such dramatic temperature reductions for such an extended period? Or are these just worst-case scare stories manufactured to direct media attention to a hitherto unappreciated aspect of the horror of nuclear war?

Following publication of the Crutzen-Birks study, Carl Sagan and two of his former students, James B. Pollack and O. Brian Toon from NASA’s Ames Research Center, together with Richard Turco and Thomas Ackerman, undertook an extensive set of calculations to check the estimates presented in the Ambio paper. The Sagan group had already been sensitized to the possibilities of major climatic disruptions due to dust in the atmosphere by their work on the Mariner 9 probe to Mars in 1971. It seemed that when the probe arrived, a massive Martian dust storm was under way. While waiting for the storm to abate, Sagan noticed that the instruments on the probe recorded atmospheric temperatures considerably higher, as well as surface temperatures much lower, than normal. Later, Sagan’s group began to apply some of the same techniques used in analyzing the Martian dust storm data to similar phenomena generated by volcanic eruptions on Earth. So when the Crutzen-Birks report came out, the NASA team was well positioned to do a detailed computational investigation of the situation.

Using their model, the Sagan group produced a paper that has become famous in nuclear winter circles—and not just for its science. This paper, known under the label “TTAPS” from the last names of its five authors, was published in the prestigious American journal Science just before Christmas 1983. To maximize the public exposure of the paper’s conclusions, Carl Sagan arranged a prepublication press conference on Halloween to announce the paper’s frightening conclusions. As a bit of unsubstantiated scientific gossip, in certain corners of the climatological community it was rumored that Sagan chose this especially dramatic moment to call public attention to the nuclear winter scenario in an effort to garner support for a Nobel Peace Prize nomination. Well, why not? After all, the subsequent East-West dialogue on scientific and political issues surrounding the nuclear winter scenario spawned by the paper’s conclusions certainly merits some kind of recognition.

The TTAPS group concluded that a major nuclear exchange in the Northern Hemisphere would result in a short-term temperature drop of almost forty degrees (Fahrenheit) and a total recovery time of nearly one year. By way of comparison, even a one-degree long-term drop in temperature would eliminate all wheat growing in Canada, and a ten-degree drop is typical for an Ice Age. But the TTAPS model was not beyond reproach: it was one-dimensional in its assumption that particles of dust and smoke could move vertically but not spread out in space. This kind of assumption implies that the atmosphere just sits there and radiates energy up and down. In other words, the model allows no movement of energy from one location to another across the surface of the globe or through the atmosphere.

In the

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