For reasons that will remain obscure, I was recently reading a 1978 volume of the journal Oceanus, published by the Woods Hole Oceanographic Institution. And in light of the tripe we often hear about how in the 1970s scientists were worried about a New Ice Age, one passage in particular stuck out to me. It’s from a paper by one John Imbrie, a Brown University oceanographer, entitled “Global Perspectives on our Changing Climate” (p. 65-70, Number 4, Fall Issue 1978, “Oceans and Climate”). Here’s what it had to say about this subject:
…there is no doubt that the 40 year cooling trend exhibited by the hemispheric average is real, and demands an explanation. Unfortunately, this phenomenon–like so many other characteristics of climate–is not fully understood.
Despite this uncertainty, some journalists and other writers–eager to dramatize a blizzard or draw attention to a prolonged cold snap–publish interpretations each winter based on the observed 40-year cooling trend. The logic of these prognostications is simple: having persisted for many decades, the trend can be expected to continue indefinitely, until the Earth enters another ice age. It is even possible to calculate when this new ice age will occur; given a 0.6 degree Celsius decline every 40 years, it would take 400 years to reach a temperature level characteristic of the last major ice age, some 6 degrees Celsius cooler than today.
However, before those readers of Oceanus who live in New England rush to put their homes up for sale and move to the Sunbelt, they should remember that making predictions based on trends of unknown origin is a risky business indeed–a principle that many investors in the stock market will confirm. In fact, many modern prophets of climatic doom have no more justification than the soothsayers of old, who, on observing a three-month cooling trend each autumn, built mid-winter bonfires to encourage the god of the sun.
Um, it doesn’t seem like this scientist was very worried about a “new Ice Age” back in 1978, even if perhaps the popular press was….