The Warming World Of Wally Broecker, 35 Years Later

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Thirty-five years ago, on August 8, 1975, geoscientist Wallace Smith Broecker published “Are we on the brink of a pronounced global warming?” in the journal Science, the first time the iconic phrase “global warming” was used in a scientific paper. Synthesizing decades of earlier work, Dr. Broecker — known by all as Wally — accurately predicted “that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide.”

The past 35 years have seen humanity answer Wally’s question in the affirmative, running a radical experiment on the only planet we inhabit. Carbon dioxide levels have risen 40 percent to 392 parts per million from pre-industrial levels of 280 ppm, and the global mean temperature has risen 0.8 C, on 1.3 trillion tons of carbon dioxide. Humanity has produced 60 percent of that global warming pollution since Broecker’s paper was published. As a result, the planetary ecosystem has fundamentally changed — weather has become more extreme, seasons have shifted, and global ice and snow is in decline — with more rapid and radical change on its way.

“To those who even today claim that global warming is not predictable,” climatologist Stefan Rahmstorf writes at the peerless Real Climate blog, “the anniversary of Broecker’s paper is a reminder that global warming was actually predicted before it became evident in the global temperature records over a decade later.”


In fact, one can even go back to 1896, when Swedish scientist Svante Arrhenius predicted that the burning of coal could eventually double atmospheric CO2, leading to a temperature increase of several degrees Celsius, although he believed such a day was far into the future. For the next fifty years, most scientists considered manmade climate change an unlikely speculation.

In the scientific explosion following World War II, however, scientists began using new measurements and the new digital computers to revisit the effect of man’s carbon dioxide pollution on the climate, and our modern understanding of the greenhouse effect developed through the work of pioneering scientists. By the end of the 1950s, Frank Capra had made an instructional film on manmade global warming and Robert Revelle had testified before Congress about the “large scale geophysical experiment” mankind was conducting with industrial greenhouse pollution.

The year 1965 marked the first time the threat of manmade global warming was brought to the President’s desk, in an extended report for Lyndon B. Johnson by top climate scientists, including Revelle, Charles Keeling (whose measurements of atmospheric carbon dioxide from Mauna Loa have become the most remarkable graph in climate science), and the young Wally Broecker. “By the year 2000,” they wrote, carbon dioxide pollution might “produce measurable and perhaps marked changes in climate, and will almost certainly cause significant changes in the temperature and other properties of the atmosphere.”

In the years leading up to Broecker’s global warming paper, the field rapidly advanced with the launch of the first weather satellites, the mathematical understanding of chaos theory — by MIT’s Ed Lorenz, and the rise of physical oceanography. Several groups of scientists competed to test the limits of supercomputers with general circulation models that simulated the planetary ocean-atmosphere interactions that generate the global climate, a practice that continues to this day.

By the end of the 1970s, climate scientists around the world were coming to the consensus that Broecker’s analysis was right — the exponential rise in carbon dioxide emissions would overcome natural cooling cycles and the effects of aerosol pollution to dangerously warm the planet within decades. “Man is setting in motion a series of events that seem certain to cause a significant warming of world climates over the next decades unless mitigating steps are taken immediately,” warned a 1979 report by top climatologists for the Carter White House, recommending “[e]nlightened policies in the management of fossil fuels and forests” to “delay or avoid these changes.”


Increasingly, the scientific enterprise has shifted toward the measurement of the changes wrought by global warming in every corner of the world, and toward a new emphasis on civilizational risk management and public engagement. However, the interface between research and policymaking has been poisoned by the influence of corporations and individuals opposed to any restrictions on carbon pollution (even ones based on free market principles). Using lessons learned from the tobacco industry’s efforts to deny the dangers of its product, global-warming polluters have poured their vast resources into a long-running campaign of deceit to corrupt efforts to make policy at local, national, and international levels. Today’s climate scientists face intimidation, slander, and even threats of criminal prosecution for their work to illuminate a way to preserve the human experiment on our burning planet.

After Wally Broecker coined “global warming,” the 1980s followed as the hottest decade on record. The 1990s were even hotter, and the 2000s hotter still — at an increasing rate despite a natural cooling cycle, just as Broecker predicted. The past twelve months have been the hottest in history, bringing continent-wide heat waves, freak storms, and unprecedented rains that have devastated millions from Nashville to Moscow, from Oklahoma City to the French Riviera. Having predicted this future, Broecker now investigates potential triggers for abrupt climate change and researches methods to capture carbon dioxide pollution, because, he says, “We are going to need some way to bail ourselves out.”

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