The Keeling Curve
San Diego, San Diego County, California
Marker Inscription
ACS Chemistry for Life (R) National Historic Chemical Landmark The Keeling Curve Scripps Institution of Oceanography University of California, San Diego La Jolla, California In 1958, Charles David Keeling (1928-2005) of Scripps Institution of Oceanography began a cooperative pogram for the study of atmospheric carbon dioxide (CO2) at the newly estabilished Mauna Loa Observatory of the U.S. Weather Bureau and other sites around the world. By 1960, Keeling revealed two significant findings, reporting the first quantitative estimate of Earth's natural seasonal CO2 oscillations while also discovering a steady annual increase in CO2, the most significant greenhouse gas contributing to global climate change. Keeling advanced our understanding of mankind's impact on Earth by linking fossil fuel emissions to rising levels of CO2. His dedication to continuous and accurate measurements enabled these data to become an unequivocal record of the global rise in CO2 and an icon of atmospheric science. American Chemical Society June 12, 2015
Erected by American Chemical Society National Historic Chemical Landmarks
The Story
In 1958, Scripps scientist Charles David Keeling launched a program to measure atmospheric carbon dioxide from the newly built Mauna Loa Observatory and other sites worldwide. Within two years his data revealed both the Earth's natural seasonal CO2 rhythm and — more consequentially — a steady, relentless annual rise, which he linked to the burning of fossil fuels. His insistence on continuous, precise measurement turned the resulting Keeling Curve into one of the defining records of modern science.
Why it matters
Keeling's measurements gave the world its first unequivocal evidence of human-driven climate change, reshaping science, policy, and how humanity sees its own footprint.
The story behind this marker
AI contextThe era
By the late 1950s, American science was riding a wave of ambition and public investment. The postwar years had made research a national priority, and 1957–58 in particular was marked as the International Geophysical Year, a global effort to study the planet as a single connected system. It was in that atmosphere of large-scale, cooperative science that this story begins.
Charles David Keeling came to the Scripps Institution of Oceanography in La Jolla, California, one of the country's premier centers for studying the oceans and the atmosphere. In 1958 he launched a program to measure atmospheric carbon dioxide, setting up observations at the newly established Mauna Loa Observatory in Hawaii and at other sites around the world.
At the time, no one knew with any precision how much carbon dioxide was in the air, or whether it was changing. The very idea that a single, patient set of measurements could reveal something profound about the whole planet was itself part of the era's scientific optimism.
People & events
Keeling's genius lay less in a single dramatic discovery than in an almost stubborn devotion to doing one thing supremely well: measuring accurately, continuously, and without letup. He chose remote, clean-air sites like Mauna Loa precisely so that his instruments would sample the broad atmosphere rather than local pollution.
By 1960 — just two years in — his data had already yielded two landmark findings. First, he produced the first solid quantitative estimate of the Earth's natural seasonal breathing: carbon dioxide rises and falls each year as the planet's vast forests leaf out and go dormant. Second, and far more consequentially, he detected a steady, year-over-year increase in the background level of carbon dioxide.
Keeling connected that relentless rise to the burning of fossil fuels, linking human activity directly to a change in the composition of the whole atmosphere. He continued the record for decades, and it was carried on after his death in 2005 — an unbroken line of measurement that became known, fittingly, as the Keeling Curve.
Its place in the American story
Few sets of measurements have changed the world's understanding of itself as much as this one. Carbon dioxide is the most significant greenhouse gas contributing to climate change, and Keeling's work provided the first unequivocal, continuous record of its global rise. What had been speculation became something you could see plotted on a page.
The Keeling Curve — that jagged, ever-climbing line — became an icon of atmospheric science, reproduced in textbooks, congressional hearings, and international negotiations the world over. It reframed a scientific question as a human one: this is a record of our own fingerprint on the sky.
The achievement was honored as a National Historic Chemical Landmark, recognition that patient, precise chemistry can reshape not only science but policy and the way an entire civilization sees its place on the planet. It stands as a monument to the idea that careful measurement, sustained over a lifetime, can reveal truths no single experiment ever could.
If you visit
The Scripps Institution of Oceanography sits on the bluffs of La Jolla, where the California coast meets the wide Pacific — a fitting home for research into the planet's great connected systems. Coming here, you trade the drama of a battlefield or a grand hotel for something subtler: the birthplace of an idea that reshaped how humanity understands its future.
Stand near the marker and consider the distance between this beautiful, ordinary-seeming coastline and the far-off summit of Mauna Loa where so much of the data was gathered. The power of this place is in the imagination it demands: a single line on a graph, built one careful reading at a time.
It makes a rewarding stop for any traveler drawn to science and the sea, and it pairs well with the tide pools, beaches, and ocean overlooks of the La Jolla coast. Bring your curiosity — this is a landmark you appreciate by thinking as much as by looking, and it lingers with you long after you've driven away.
Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.
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Related people
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