ICE CORE DATA OF ATMOSPHERIC CARBON-MONOXIDE OVER ANTARCTICA AND GREENLAND DURING THE LAST 200 YEARS

The first polar ice core measurements of carbon monoxide compatible wi th atmospheric data were obtained using an improved experimental proto col. A new CO extraction method has been developed with special care t o eliminate any CO contamination. The procedure has been applied to ic e core samples originating from Antarctica and Greenland in order to r econstruct past CO variations over the last 200 years. Consistent resu lts in terms of atmospheric concentrations are obtained. We find that CO concentration started to increase over Greenland around 1850 and th at, by contrast, CO levels at high southern latitudes remained fairly constant between 1860 and 1916. Based on available data on past CO sou rces, a scenario is proposed for the CO increase observed in Greenland . In addition, our Greenland CO results suggest that simulations of pr eindustrial CO distribution could have underestimated CO concentration s mainly in the northern hemisphere leading to an overestimate of the change since preindustrial times, and to an underestimate of the past interhemispheric gradient of carbon monoxide.