The Keeling Curve: How a Nature-Loving Geochemist Kickstarted Climate Science
Among climate scientists, Charles David Keeling and the "Keeling Curve" are famous, even revered. Walk into the National Academy of Sciences building in Washington, D.C. You'll find that one wall shows Darwin's finches; next to that is the double helix; and beside that, the Keeling Curve: a graph depicting the increase in atmospheric carbon dioxide over the past half-century.
And yet Keeling and his work are largely unknown, even to most smart, educated, successful Americans. Eric Roston, author of The Carbon Age, says this typifies the general ignorance about global warming. Writing in the Nichols Institute blog, The Climate Post, Roston notes that in 2009, Deutsche Bank installed a huge billboard in New York, across the street from Madison Square Garden. In the spirit of the famous "National Debt Clock," it shows a running tally of the tons of CO2 humans are putting into the atmosphere. Roston wonders what would happen if instead it were the Keeling Curve? He even envisions other Keeling Curves on display in Times Square, at the New York Stock Exchange, in Parisian art installations, or projected onto clouds on Earth Day like the Bat Signal.
The saddest irony of Keeling's relative obscurity is that the Keeling Curve makes global warming so terribly understandable. Its' message proclaims the one most basic fact of climate change: Carbon dioxide levels have been climbing, and are continuing to rise at an extraordinary and accelerating pace. Revealed by the graph of Keeling's measurements, it is a message that can’t be missed by any child or adult of reasonable intelligence.
Science historian Spencer Weart, author of The Discovery of Global Warming, credits Keeling with being the first who discovered evidence that global warming had to be taken seriously. Says Weart in a recent interview, "Before Keeling no one devoted more than a year or so of effort to the question, and then they turned to other matters that seemed more important. Actually, had it not been for Keeling, it might have been another ten or twenty years before we knew about it."
Charles David Keeling (everybody simply called him Dave) grew up in a series of Chicago suburbs in the 1930s. His parents took him to the Colorado Rockies when he was four years old, a trip that ignited a lifelong love affair with nature and the remote mountainous areas of western North America. As a child he kept an album in which he pasted pictures not of ballplayers or cowboys, but only of mountains.
His dream, by the time he entered the University of Illinois as an undergraduate chemistry major, was to practice science in the great outdoors. When he graduated from Northwestern in 1953 with a PhD in chemistry and a minor in geology, he wrote letters offering his postdoc services to 10 universities that had geology departments, all west of the Coninental Divide. He got two positive responses, one from Caltech, where a 37-year-old Harrison Brown was starting the world's first department in geochemistry, the study of the planet and how it works. Keeling went to Caltech.
One day, Brown ventured the opinion that the amount of CO2 in a freshwater river would be about the same as in the air surrounding the river. It was a casual, random speculation -- but Keeling jumped on it, telling Brown he simply didn't agree. Brown good-naturedly responded, "Well, Keeling, why don't you go out there and see if you can prove it?"
Keeling saw his big chance to do outdoor research in nature. Measuring atmospheric CO2 was (and remains) a highly complex and demanding discipline. In those days it yielded wildly variable results. It was generally presumed the accuracy of CO2 measurements, which bounced all over the spectrum from 150 ppm to 450 parts per million (ppm), depended on where they were taken, who took them, and with what equipment. Another scientist might have simply taken days to come up with an answer, but not Keeling, who was always precise, and didn't trust the measuring equipment then in use. He decided to design his own and, as he put it, "make it 10 times more accurate then it needed to be." It took him two years.
In May of 1955, Keeling decided he was finally ready. He drove up to Big Sur with his wife and their two- month-old baby, pitched a tent near the Big Sur River, and over the course of two days took nine measurements. All the air measurements showed the same number: 310 ppm. (The river water measurements, because of decaying leaves in the water, were only slightly higher.) Any other researcher might have stopped right there, but as Keeling later recalled, he was “having fun.” For a year after that, he took measurements all over: in Yosemite, the Sierra Nevadas, the Cascades, Olympic National Park, eastern California's Inyo Mountains. Everywhere that same number came up: 310 ppm.
This truly was news. Was it possible there was a single CO2 number for the entire planet? Back at Caltech, he gave a talk about his findings and as it turned out, his timing was very good. The International Geophysical Year (IGY) was in the planning stages, and Roger Revelle, a principal IGY organizer and director of the Scripps Institute of Oceanography, engaged Keeling to measure CO2 all over the planet: at the South Pole, atop Mauna Loa in Hawaii, and on board a moving ship, as well as at Scripps.
Between 1958 and 1960 Keeling saw the numbers rise from 318 ppm to 321 ppm. It was obvious they were steadily going up. Except for seasonal variations, (CO2 concentrations always go down slightly in winter) they never went down. The long-held, comfortable assumption that most of the CO2 produced by industrial emissions was being absorbed by the oceans was clearly not true.
By 1963, Keeling was getting locked into an ongoing struggle with various mid-level government bureaucrats who mistakenly saw his work as “routine” and were continually seeking to cut off his funding and put an end to the program so they could take it over. A lesser man would have quit but Keeling battled bureaucrats for thirty years to maintain his standards. It was 1995 before he was satisfied that the National Oceanic and Atmospheric Administration (NOAA) would be able to maintain precise, stable measurement standard. It's thanks to Keeling’s tenacity that we have an accurate and nearly continuous record of CO2 emissions between 1958 and today.
On the day of Keeling’s passing in June 2005 -- he had a heart attack as he was hiking with his son in the Bitterroot Mountains of Montana -- CO2 was at 380ppm. Today it is 395ppm, and more than half the increase in the past 110 years has taken place in the last 25.
Wallace Broecker (who, beginning with a Science article in 1975, popularized the term “global warming”) said of Keeling: "One man, even a quiet scientific man, can make a difference in the world. If Keeling had not been so devoted to measuring carbon dioxide, the debate on global warming would be even more mired in polemics than it is now. Instead the 'Keeling curve' of carbon dioxide at Mauna Loa has become one of the debate's few universally acknowledged truths.”
How about erecting that electronic billboard in Times Square?
Image credit: Wikipedia