The chapter opens with the “global cooling” story — the claim that 30 years ago there was a scientific consensus that the planet was cooling, comparable to the current consensus that it’s warming.
Um, no. Real Climate has the takedown. What you had in the 70s was a few scientists advancing the cooling hypothesis, and a few popular media stories hyping their suggestions. To the extent that there was a consensus, it was that there wasn’t much evidence for anything, and more research was needed.
The real purpose of the chapter is figuring out how to cool the Earth if indeed it becomes catastrophically warmer. (That is the “global cooling” in our subtitle. If someone interprets our brief mention of the global-cooling scare of the 1970’s as an assertion of “a scientific consensus that the planet was cooling,” that feels like a willful misreading.)
The headlines have been harrowing, to say the least."Some experts believe mankind is on the threshold of a new pattern of adverse global climate for which it is ill-prepared," one New York Times article declared. It quoted climate researchers who argued that "this climatic change poses a threat to the people of the world."A Newsweek article citing a National Academy of Sciences report, warned that climatic change "would force economic and social adjustments on a worldwide scale." Worse yet, "climatologists are pessimistic that political leaders will take any positive action to compensate for climatic change or even to allay its effects."Who in his or her right mind wouldn't be scared of global warming?But that's not what these scientists were talking about. These articles, published in the mid-1970s, were predicting the effects of global cooling.Alarm bells had rung because the average ground temperature in the Northern Hemisphere had fallen by .5 degrees Fahrenheit (.28 degrees Celsius) from 1945 to 1968. Furthermore, there had been a large increase in snow cover, and between 1964 and 1972, a decrease of 1.3 percent in the amount of sunshine hitting the United States. Newsweek reported that the temperature decline, while relatively small in absolute terms, "has taken the planet about a sixth of the way towards the Ice Age average."The big fear was a collapse of the agricultural system. In Britain, cooling had already shortened the growing season by two weeks. "[T]he resulting famines could be catastrophic," warned the Newsweek article. Some scientists proposed radical warming solutions such as "melting the arctic ice cap by covering it with black soot."These days, of course, the threat is the opposite. The earth is no longer thought to be too cool but rather too warm.