Global Warming First Discovery
It was 50 years ago that a young American scientist, Charles David Keeling, began tracking CO2 in the Earth's atmosphere at two of the world's last wildernesses - the South Pole and the summit of the Mauna Loa volcano in Hawaii.
Back in the 1950s, when Keeling began his experiments, no-one knew whether the CO2 released from the burning of fossil fuels (coal, oil/petroleum and natural gas) would end up in the atmosphere or be fully absorbed by oceans and forests.
His very precise measurements produced a remarkable data set, which first sounded alarm bells over the build-up of the gas in the atmosphere, and eventually led to the tracking of greenhouse gases worldwide. The curve set the scene for the debate over climate change, and policies, sometimes controversial, that address the human contribution to the greenhouse effect.
The reason behind starting the measurements was to see if it was possible to track what at that time was only a suspicion: that atmospheric CO2 levels might be increasing owing to the burning of fossil fuels. To do this, a location was needed very far removed from the contamination and pollution of local emissions from cities; therefore Mauna Loa, high on a volcano in the middle of the Pacific Ocean was chosen.
Professor Keeling discovered that carbon dioxide was rising continuously and that there were annual fluctuations in carbon in the atmosphere (the little squiggles on the line), caused by seasonal variations in plant growth and decay. When he started his measurements in 1958, CO2 levels were around 315 ppmv (parts per million by volume - that is 315 molecules of CO2 for every one million molecules in the air); by the year 2005 they had risen to about 378 ppmv.
Today, carbon dioxide levels are sampled weekly at about 100 sites around the world. Flasks filled with air are taken to a laboratory, where they are analysed for carbon dioxide, other greenhouse gases and pollutants. Aircraft collect similar samples at higher altitude, while space-borne sensors detect some gases remotely throughout the atmosphere.
Without this curve, and Professor Keeling's tireless work, our understanding and acceptance of human-induced global warming would be 10-20 years less advanced than it is today. Charles Keeling died in 2005, aged 77. He continued his research into carbon dioxide at the Scripps Institution of Oceanography in San Diego, US, until his final day. By then he had authored nearly 100 research articles and had received the National Medal of Science - the US's highest award for lifetime achievement in scientific research. His son, Professor Ralph Keeling, also a geochemist at Scripps, continues his work.
14 December 2007