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," said 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 the Earth breathes, a key to understanding the global climate that has nurtured civilization but that may now be changing.
Charles David Keeling, 76, pioneered the measurement of carbon dioxide in the atmosphere almost half a 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.
With two lifetimes' work, mostly at the Scripps Institution of Oceanography in San Diego, this innovative duo has given science a bedrock for studying climate change, a foundation whose importance increases as concern grows over rising temperatures, melting glaciers and other effects of the buildup of "greenhouse gases," particularly carbon dioxide, CO2.
The elder Keeling's progress, in the face of skeptical bureaucrats, wasn't always smooth. "It took some plain old cussedness on the part of Dave Keeling for him to accomplish what he did," said Michael B. McElroy, Harvard University earth scientist.
But Dave Keeling's achievement was finally recognized with a National Science Medal in 2002, when Scripps director Charles Kennel described his findings as "pertinent to every human being on the globe."
Keeling himself says that "if you want to know anything about what the future holds," his findings are even more pertinent when combined with his son's work on oxygen.
In 1955, young geochemist Dave Keeling was camped out at California's Big Sur State Park, taking air samples in flasks and precisely measuring the carbon dioxide with a manometer, a device of his own making.
"Nobody had done it before, but advances in technology made it possible," said Keeling, a smiling man with a gray thatch of hair and jeans-and-sneakers casualness.
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 the 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 finding was that carbon dioxide made up 315 parts per million in the atmosphere, 12% more than the 280 that ice-core samples show was the level before the Industrial Revolution -- before man's extensive burning of fossil fuels that spew out CO2.
In 1958, he moved his main sampling operation to a 2-mile-high U.S. Weather Service station atop Hawaii's Mauna Loa volcano, a spot practically free of contaminated air. Using a more precise infrared analyzer, he found that the atmosphere's CO2 was growing by about 1 part per million each year.
Analyzing the data in his lab, he was the first to detect the Earth's annual "breathing" cycle -- the dip in CO2 when Northern Hemisphere plant life absorbs the gas in the spring-summer growing season, and the spike up when decaying vegetation releases CO2 in the fall.
In the 1970s and '80s, as the "Keeling curve" charts tracked CO2'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 CO2 measurement program.
Keeling countered that his program's long-term continuity was vital to consistent tracking of CO2. Today, he views the repeated showdowns in plain terms: "You set up a dry-cleaning establishment, and somebody comes along and decides he wants a dry-cleaning establishment, and the best way is to get rid of yours."
With the help of the Scripps leadership and Washington allies, Keeling's program survived. Today, his original gas analyzer operates next to an NOAA device atop Mauna Loa, and both show that CO2 rose to a record 379 ppm this winter -- more than one-third higher than the pre-industrial level. Meantime, global temperatures are also rising.
"I've watched for 45 years to see this thing unfold," he said.
It was 45 years ago too that he remembers being with Ralph, second-born of Dave and Louise Keeling's five children, at Mt. 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.