Gauging how Earth breathes
SAN DIEGO – When father-son scientists Dave and Ralph Keeling sit down at the piano and violin, they merge their minds in the flowing warmth of a Brahms sonata or the energy of a Beethoven.
When they go their separate ways to their labs, it’s the rhythm of the planet they feel.
“The Earth is doing a beautiful, simple dance for us,” says Ralph, fingers tracing waves in the air. “And we’re watching.”
What they’ve watched and sampled, and measured out in undulating graphs of enduring scientific importance, is nothing less than how Earth breathes, a key to understanding the global climate that has nurtured civilization but now may be changing.
Charles David Keeling, 76, pioneered the measurement of carbon dioxide in the atmosphere almost a half-century ago on a Hawaiian mountaintop. Decades later, his son devised a way to gauge atmospheric oxygen, the other half of the global respiratory cycle.
Together, with two lifetimes’ work, mostly at the Scripps Institution of Oceanography in San Diego, this innovative duet has given science a bedrock for studying climate change, a foundation whose importance increases as concern grows over rising temperatures, melting glaciers and other apparent effects of the buildup of “greenhouse gases,” particularly carbon dioxide, or CO-2.
Carbon dioxide and other greenhouse gases, such as methane, trap heat. Such gases occur naturally, but industrial processes also add enormous amounts to the atmosphere. The buildup tends to raise Earth’s temperature, and that could shift climate zones, raise ocean levels via heat expansion and glacial melting, and cause other disruptive changes.
Keeling’s consistent early finding was that carbon dioxide comprised 315 parts per million in the atmosphere, 12 percent more than the 280 that ice-core samples show was the level before the Industrial Revolution – before man’s extensive burning of coal, oil and other fossil fuels that spew out CO-2.
In 1958, he moved his main sampling operation to a two-mile-high U.S. Weather Service station atop Hawaii’s dormant Mauna Loa volcano, a spot practically free of contaminated air. Using a more precise infrared analyzer to measure the gas, he found that the atmosphere’s CO-2 was growing by about 1 part per million each year.
Analyzing the data in his lab in San Diego, he was the first to detect Earth’s annual “breathing” cycle – the dip in CO-2 when northern hemisphere plant life absorbs the gas in the spring-summer growing season, and the spike up when decaying vegetation releases CO-2 in the fall.
In the 1970s and 1980s, as the “Keeling curve” tracked CO-2’s accumulation in the skies, the scientist’s fortunes declined among Washington agencies funding the research. First, National Science Foundation officials argued that his work was too “routine” and unworthy of support. Then the National Oceanic and Atmospheric Administration said it planned to supplant him with its own CO-2 measurement program.
With the help of the Scripps leadership and Washington allies, Keeling’s program survived. Today his original gas analyzer operates next door to an NOAA device atop Mauna Loa, and both show that CO-2 rose to a record 379 parts per million this winter – more than one-third higher than the pre-industrial level. Meanwhile, global temperatures also are rising.
“I’ve watched for 45 years to see this thing unfold,” Keeling said.
It was 45 years ago, too, that he remembers being with Ralph, second-born of Dave and Louise Keeling’s five children, at Mount Rainier in Washington, when the little boy looked up at the ice and asked, “How you make glaciers?”
“He got a start in natural science at the age of 2 1/2 ,” the father said with a laugh.
Ralph Keeling, now a youthful 47, said he grew to appreciate his father’s work while studying science at Yale and Harvard. Then, as a doctoral candidate, he devised the first technique, using a light-gauging instrument called an interferometer, to measure atmospheric oxygen accurately.
“The prevailing opinion was that it was impossible to measure,” Dave Keeling recalled.
Oxygen can provide critical clues about the atmosphere. It’s consumed in fossil fuel burning; it’s produced as forests and other plants consume CO-2. Precise tracking of this oxygen-carbon dioxide balance can help scientists distinguish between CO-2 absorbed on land and that absorbed by the oceans. That, in turn, can help in forecasting trends and planning possible remedies.
Ralph and colleagues now have nine sampling stations worldwide, and their findings are used by the Intergovernmental Panel on Climate Change, the U.N.-organized network of scientists that is warning of impending climate change.
The prospect of unpredictable, abrupt change worries the younger Keeling. “We are moving into a warmer world,” he said.
For years, his father took no public stand on global warming. But the accumulating evidence has become irrefutable, Dave Keeling now says. “There was this long stage of denial about the temperature rising,” he said.
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