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Decision XXVII/7 : Investigation of carbon tetrachloride discrepancies

Reiterating its concern about the discrepancy between observed atmospheric concentrations and data on carbon tetrachloride reported in the 2014 assessment reports of the Technology and Economic Assessment Panel and the Scientific Assessment Panel, indicating that the mismatch between bottom-up inventories and global top-down estimates of carbon tetrachloride remains unresolved,

Noting with concern that derived emissions of carbon tetrachloride, based on its estimated lifetime and its accurately measured atmospheric abundances, have become much larger over the last decade than those from reported production and usage, notwithstanding that some of the discrepancy could be explained by additional sources unrelated to reported production, such as contaminated soils and industrial waste, and that additional explanations could include underreported releases to the atmosphere and incorrect partial lifetimes (stratosphere, ocean or soil),

Recalling decisions IV/12, X/12, XVI/14, XVIII/10, XXI/8 and XXIII/8,

  1. To request the Technology and Economic Assessment Panel and the Scientific Assessment Panel to continue their analysis of the discrepancies between observed atmospheric concentrations and reported data on carbon tetrachloride and to report and provide an update on their findings to the Twenty-Eighth Meeting of the Parties;