During the mid-1900s, a growing number of scientists began wondering what effect, if any, the burning of fossil fuels had on the concentration of carbon dioxide in the atmosphere. Many scientists just assumed that any additional CO² that went into the air would simply be absorbed by the oceans and that the concentration in the air would remain fairly steady. The problem was that there was no
real way of accurately measuring the balance of different gases in the atmosphere.

Charles David Keeling didn’t like assumptions. In 1953, Keeling was working as a postdoctoral fellow in geochemistry at the California Institute of Technology. For three years, he developed a system for measuring tiny changes in the CO² concentration of the air. He began collecting data showing that, outside of cities and forests, the concentration of CO² in the atmosphere was fairly constant all over the planet. This value is now called the atmospheric background of carbon dioxide.

In 1958, with the support of the U.S. Weather Service Keeling set up a monitoring station at the Mauna Loa Observatory in Hawaii, which is on top of an extinct volcano reaching 11,135 feet (3,400 m) in height. There, far from sources of air pollution, he began taking detailed measurements of the CO² background in the air. At the time he found that the concentration was 310 parts per million (ppm). He continued taking measurements during the next 45 years and what he saw confirmed the worst fears of climate scientists. The oceans were indeed absorbing some of the extra CO², but not all of it. During Keeling’s studies the atmospheric background of CO² steadily increased. Today it stands at 388 ppm. What’s worse is that as more fossil fuels are burned, the rate of increase is accelerating. Some scientists estimate that if the trend continues, CO2 level of 500 ppm or more may be common by the end of the century.

Charles Keeling died in 2005. His son Ralph, who is also an atmospheric scientist, is continuing his work. Keeling will always be remembered for his groundbreaking work. The plot of the data he collected is known by climate scientists around the world as the Keeling Curve. – Tomecek, Stephen M.| Global Warming and Climate Change