Atmos. Chem. Phys. 16, 4147–4157 (2016)

Increasing temperatures in the Arctic could accelerate the thawing of the subsea permafrost in the East Siberian Shelf, releasing large amounts of methane — a potent greenhouse gas — into the atmosphere. Previous estimates based on oceanographic observations suggest massive emissions from these shelves, but this remains controversial due to the large uncertainty associated with the methane fluxes partly due to their large spatial and temporal variability.

Antoine Berchet, from the Institut Pierre Simon Laplace in France, and colleagues used a top-down approach and combined atmospheric methane observations with high-resolution transport and mixing simulations to resolve the seasonal cycle of these emissions and evaluate the potential for such large emissions from the Siberian Shelf.

The analysis suggests that large methane emissions are possible in the summer, but not during the rest of the year, indicating that previously suggested annual rates cannot be sustained over this area. The method used suggests that the range of methane emissions from the Siberian Shelf is 0.0–4.5 TgCH4 yr−1, significant at the regional scale but 6–10 times smaller than most recent estimates (8–17 TgCH4 yr−1).

Although the biases associated with the model used need to be addressed, this new analysis highlights the need to constrain the spatial and temporal variability of methane emissions in this region to reduce the uncertainties in the fluxes.