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 CH4

Carbon-13 in CH4 has decreased since 2008, but the short record (only back to 1998) combined with multiple sources precludes any simple explanation at this point. Ratios of 13C/12C in CH4 tend to be lower in the Northern Hemisphere.

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