The Norwegian Polar Institute has reported atmospheric carbon dioxide levels of 390 ppm (parts per million) at its Zeppelinfjellet atmospheric monitoring station in Ny Ålesund during the months of November and December 2008, with levels of 394 ppm CO2 reached on several days. The measurements represent the highest levels recorded since monitoring began at the station.
Direct evidence of increasing atmospheric CO2 was established forty years ago with continuous measurements made at the Mauna Loa Observatory in Hawai'i, as well as measurements of flask samples collected periodically at the South Pole. Early data showed a rise in concentration in 1959 as compared to the results of the previous year, at which time CO2 levels were approximately 316 ppm. Later analyses of ice cores and ocean floor sediment have established a record of atmospheric concentrations of carbon dioxide as far back as 800,000 years, none of which have been as high as present concentrations of CO2.
Further measurements have shown a persistent year-to-year increase, as well as a decadal acceleration in the rate of increase. Approximately 280 atmospheric monitoring stations are now scattered around the globe, supplemented by 3,000 floating buoys as well as satellites from Europe, Japan, and the United States.