Narrator: This is Science Today. This month marks the 50th anniversary of the "Keeling Curve", a historical graph measuring atmospheric carbon dioxide levels. It was started by the late Charles David Keeling of the University of California, San Diego's Scripps Institution of Oceanography. Ralph Keeling, a geochemist at Scripps says his father's graph provided the first clear evidence that carbon dioxide was accumulating in the atmosphere as the result of humanity's use of fossil fuels.
Keeling: The existence of that curve changed the discussion about global warming from being entirely about speculation up until that point to being rooted in some really hard, empirical facts. Things were changing and people needed to pay attention.
Narrator: Keeling says when the measurements began in 1958, it was curiosity-driven. Scientists got into it based on the grand exploration of the universe.
Keeling: Fifteen years later though, there were people getting into it who already had well-established concerns about how the planet was evolving. People who saw the curve and got into it for that reason.
Narrator: For Science Today, I'm Larissa Branin.
