The site where Scripps Institution of Oceanography at UC San Diego geochemist Charles David Keeling launched what has become the world's most famous record of human-caused climate change will be memorialized by the American Physical Society (APS) in a June 17 ceremony. The society added the Scripps campus to its register of historic sites for the work that began there that came to be known as the Keeling Curve. Scripps will join locations such as the Franklin Institute in Philadelphia, at which are housed implements used by Benjamin Franklin in his study of electricity; New Jersey's Bell Laboratories, where the transistor was invented; and the site at Montreal's McGill University where Ernest Rutherford first identified radioactivity. The ceremony will take place during Scripps Day, an annual event honoring alumni, students, and faculty, at Scripps' Ritter Hall. The building houses many of the original instruments Keeling invented to make ultraprecise measurements of atmospheric carbon dioxide (CO2) concentrations beginning in 1957. Over the course of several decades, Keeling and his successors demonstrated how carbon dioxide has increased to levels not seen in several hundred thousand years, and contributed significantly to society's modern understanding of climate change. The Keeling Curve through 2011 The Keeling Curve through 2011 The measurements that feed the Keeling Curve have been made atop Hawaii's Mauna Loa since 1958. The society selected the Scripps campus for the plaque dedication, however, citing it as the locale at which Keeling's crucial development of the measurements and important interactions with Scripps Director Roger Revelle took place. "Revelle's plan was to take a 'snapshot' of the planet's carbon dioxide levels at a number of locations during the International Geophysical Year (IGY) 1957-1958, and then repeat the observations a few decades later to see whether the predicted rise had occurred," the society wrote in a summary of Keeling's achievement. "But Keeling was so dedicated to precision that he was able to detect a rise within two years." Keeling died in 2005 but son Ralph, himself a geochemist at Scripps Oceanography, has continued the carbon dioxide measurement series. "This is a tremendous honor. It's great to see my father's work honored in this way," said Ralph Keeling. "Even after half a century, it's amazing how these measurements are still a center of attention and in fact continue to grow in importance." Ritter Hall, the second oldest laboratory building on campus and the home for Keeling's groundbreaking research, is appropriately named for the first director of Scripps, William Ritter, whose vision for inclusion of all fields related to the ocean environment led directly to the wide range of interdisciplinary studies at Scripps, including hiring Charles Keeling to do research on CO2. Ritter Hall was designed by Louis Gill in 1930 and completed in 1931. Gill was the nephew of the renowned, innovative architect, Irving Gill, who designed Scripps first laboratory building, the George H. Scripps Laboratory. The plaque honoring Keeling will be placed prominently on the west side of the building by the main entrance. "My father clearly had a sense he was doing this for posterity and here we are," said Ralph Keeling. "I wish we could say CO2 levels were no longer rising but we have a long way to go on that." The APS began its Historic Sites Initiative in 2004. With the addition of the Scripps campus, there are 20 locations on the society's registry in North America.