'I was able to point out that we are tenth cousins, George Bush and I'

Oceanographer Charles Keeling this week raised the alarm about a worrying rise in carbon dioxide levels

Charles Keeling is obsessed by carbon dioxide. He has been measuring it conscientiously for 46 years from the top of the Mauna Loa volcano in Hawaii. And this week, the 76-year-old professor of oceanography at Scripps Institution of Oceanography at the University of California, raised the alarm that levels of carbon dioxide, one of the major greenhouse gases believed to contribute to global warming, are growing at worrying rates.

Professor Keeling's methods have changed little since he began the first continuous record of atmospheric carbon dioxide in 1958. He takes four samples an hour from the top of four 7m towers and one m tower on Mauna Loa. A daily average is taken from six consecutive hourly measurements.

Before he began his measurements - now known as the Keeling Curve - it was thought that oceans and vegetated land areas would absorb the carbon dioxide emissions generated by the burning of fossil fuels. Professor Keeling's research made it clear that this was not the case. When the Keeling Curve began, the concentration was 316 parts per million by volume (ppmv). In 2003, it was 376ppmv. And the past two years have seen unprecedented large rise.

In 2002, President George W. Bush awarded Professor Keeling the National Medal for Science. "My son did a genealogy on the Keeling family, and I was able to point out that we are tenth cousins, George Bush and I," Professor Keeling told the American Geological Institute. "That made the conversation easier."