Climate: History, periodicity, and predictability

Only a few years ago, extraterrestrial forcing of the earth's climate machine was considered a model of last resort, to be used only when all other mechanisms, internal or stochastic, failed. With the general acceptance of the Milankovich orbital model of climate fluctuations on the 10^4‐ to 10^5‐year time scale has come a lessening of the reluctance to discuss external mechanisms as factors in climate change. This was apparent at a recent conference entitled Climate: History, Periodicity, and Predictability (in honor of Rhodes W. Fairbridge on his 70th birthday) held May 21–23, 1984, at Barnard College of Columbia University, New York City, which brought together 80 specialists from at least 12 countries. At this conference, discussions of causal mechanisms ranged from the purely terrestrial to those involving the sun and moon, the dynamics of the solar system, and even the rhythms of the galaxy.