CO2 The fossil fuel era challenge

The most important findings at the beginning of the twenties century was that the 

The longest continuous record of measurements of atmospheric CO2 concentration available in the nineteen s century was made between 1877 and 1910 at the Montsouris Observatory on the outskirts of Paris (Fig. 2.65). 

The measurements carried out in Boston by Francis Benedict between April 1909 and January 1912 are probably the longest and most precise of that time. Benedict tried carefully to avoid town influences, and by separating the values shown in Table 2.77 it is possible to derive a seasonal amplitude of about 9 ppm and a town contribution (adding to the rural background) of about 45 ppm. 

Air bubbles were extraeted using the cheese grater technique. Ice core samples weighing 500-1500 g were prepared by selecting crack-free iee and trimming away the outer 5-20 mm. Eaeh sample was sealed in a polyethylene bag and cooled to 

These atmospheric CO2 reconstructions offer a reeord of atmospheric CO2 mixing ratios from AD 1006 to 1978. Etheridge et al. (1996) reported the uncertainty of the ice core CO2 mixing ratios as 1.2 ppm. Preindustrial CO2 mixing ratios were in the range of 275-284 ppm, with lower levels between AD 1550 and 1800, probably because of the colder global climate (Etheridge et al. 1996). Law Dome ice core 

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