Calculations made in the late 1960s suggested that average temperatures would rise a few degrees within the next century.
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This finding was reinforced by computer models of the general circulation of the atmosphere, the fruit of a long effort to learn how to predict (and perhaps even deliberately change) the weather. It appeared that grave climate change could happen, and in the past had happened, within as little as a few centuries. Others figured out ingenious ways to retrieve past temperatures by studying ancient pollens and fossil shells. Over the next decade a few scientists devised simple mathematical models of the climate, and turned up feedbacks that could make the system surprisingly variable. Keeling drove home the point in 1960, showing that the level of the gas was in fact rising, year by year. The new studies showed that, contrary to earlier crude estimates, carbon dioxide could indeed build up in the atmosphere and should bring warming. What made that possible was a sharp increase of government funding, especially from military agencies with Cold War concerns about the weather and the seas. In the 1950s, Callendar’s claims provoked a few scientists to look into the question with improved techniques and calculations. Whatever the cause of warming, everyone thought that if it happened to continue for the next few centuries, so much the better. Callendar, insisted that greenhouse warming was on the way. Scientists supposed this was just a phase of some mild natural cycle, with unknown causes. In the 1930s, people realized that the United States and North Atlantic region had warmed significantly during the previous halfcentury. Indeed most thought it was obvious that puny humanity could never affect the vast climate cycles, which were governed by a benign “balance of nature.” In any case major change seemed impossible except over tens of thousands of years. Scientists found technical reasons to argue that our emissions could not change the climate. This “greenhouse effect” was only one of many speculations about climate change, however, and not the most plausible. As humanity burned fossil fuels such as coal, which added carbon dioxide gas to the Earth’s atmosphere, we would raise the planet’s average temperature. In 1896 the Swedish scientist Svante Arrhenius published a new idea. Then what did cause global climate change - was it variations in the heat of the Sun? Volcanoes erupting clouds of smoke? The raising and lowering of mountain ranges, which diverted wind patterns and ocean currents? Or could it be changes in the composition of the air itself? The discovery of ice ages in the distant past proved that climate could change radically over the entire globe, which seemed vastly beyond anything mere humans could provoke. But there were larger shifts of climate that happened all by themselves. For example, ancient Greeks and 19th-century Americans debated how cutting down forests might bring more rainfall to a region, or perhaps less. People had long suspected that human activity could change the local climate.
In the end they did win their goal, which was simply knowledge. A few took the battle into the public arena, often getting more blame than praise most labored to the end of their lives in obscurity. Even as they stretched their minds to the limit on intellectual problems that often proved insoluble, their attention was diverted into grueling administrative struggles to win minimal support for the great work. They gambled decades of arduous effort on the chance of a useful discovery, and staked their reputations on what they claimed to have found. The rest needed more subtle forms of courage. For some, the work required actual physical courage, a risk to life and limb in icy wastes or on the high seas. It is an epic story: the struggle of thousands of men and women over the course of a century for very high stakes. This excerpt is from The Discovery of Global Warming, by Spencer R.
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