SAN DIEGO -- Charles David Keeling, a pioneering climate scientist whose atmosphere measurements over a half century confirmed the steady rise in carbon dioxide worldwide, had died. He was 77.

Keeling, 77, suffered a heart attack Monday while hiking with his son near his summer home in Montana, officials with the Scripps Institution of Oceanography in La Jolla told The San Diego Union-Tribune. He had worked at the institution for half a century and was a longtime Del Mar resident.

A ceremony for the family will be held this week in Hamilton, Mont. A separate memorial is being planned at Scripps, the newspaper reported.

The scientist's record of rising carbon dioxide -- a heat-trapping greenhouse gas that occurs naturally but also is emitted by cars, power plants and other fossil-fuel burners -- became known as the Keeling Curve.

Its upward slope has mirrored humanity's escalating appetite for fossil fuels. The science behind the curve is required reading in science textbooks.

Keeling won several awards in recent years, including the National Medal of Science in 2002 and the Tyler Prize for Environmental Achievement in April.

Keeling was born in Scranton, Penn., on April 20, 1928. He received a bachelor's degree in chemistry from the University of Illinois in 1948 and a doctorate in chemistry from Northwestern University in 1954.

At Scripps, there have been discussion about Ralph Keeling, Keeling's son and an atmospheric scientist at Scripps, taking over his father's lab and continuing his work, Keeling's colleagues told the Union-Tribune.

Keeling is survived by his wife, Louise; his children, Andrew, of Zurich, Switzerland; Ralph, of La Jolla; Emily, of Boulder, Colo.; Eric, of Missoula, Mont., and Paul, of Vancouver, British Columbia; and six grandchildren.