In 1956 Roger Revelle and Hans Suess, geochemists at the Scripps Institution of Oceanography in California, pointed out the need to measure carbon dioxide in the air and ocean so as to obtain "a clearer understanding of the probable climatic effects of the predicted great industrial production of carbon-dioxide over the next 50 years." In other words, they wanted to figure out how dire the situation would be today. That they had to argue the importance of such observations now seems astonishing, but at the time scientists did not know for certain whether the carbon dioxide spewing out of tailpipes and smokestacks would indeed accumulate in the atmosphere. Some believed that it would all be absorbed benignly by the sea or be happily taken up by growing plants on land.

Revelle and the young researcher he hired for this project, the late Charles David Keeling, realized that they had to set up equipment at remote locations, far from local sources and sinks of carbon dioxide, which would cause the measurements to vary erratically. One spot they chose was about as far from industrial activity and vegetation as anyone could get: the South Pole. Another was at a newly established weather station atop Mauna Loa in Hawaii.