NOTICE: CDIAC as currently configured and hosted by ORNL will cease operations on September 30, 2017. Data will continue to be available through this portal until that time. Data transition plans are being developed with DOE to ensure preservation and availability beyond 2017.

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Carbon-13 in CO2

Carbon-13 in CO2 is decreasing, as the fraction of atmospheric CO2 that is realized from combustion of fossil carbon is increasing. Ratios of 13C/12C in CO2 tend to be lower in the Northern Hemisphere, suggesting a fossil-fuel source that resides mainly in the Northern Hemisphere.

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