| Summary: | Sharp rises in the atmospheric abundance of ethane (C _2 H _6 ) have been detected from 2009 onwards in the Northern Hemisphere as a result of the unprecedented growth in the exploitation of shale gas and tight oil reservoirs in North America. Using time series of C _2 H _6 total columns derived from ground-based Fourier transform infrared (FTIR) observations made at five selected Network for the Detection of Atmospheric Composition Change sites, we characterize the recent C _2 H _6 evolution and determine growth rates of ∼5% yr ^−1 at mid-latitudes and of ∼3% yr ^−1 at remote sites. Results from CAM-chem simulations with the Hemispheric Transport of Air Pollutants, Phase II bottom-up inventory for anthropogenic emissions are found to greatly underestimate the current C _2 H _6 abundances. Doubling global emissions is required to reconcile the simulations and the observations prior to 2009. We further estimate that North American anthropogenic C _2 H _6 emissions have increased from 1.6 Tg yr ^−1 in 2008 to 2.8 Tg yr ^−1 in 2014, i.e. by 75% over these six years. We also completed a second simulation with new top-down emissions of C _2 H _6 from North American oil and gas activities, biofuel consumption and biomass burning, inferred from space-borne observations of methane (CH _4 ) from Greenhouse Gases Observing SATellite. In this simulation, GEOS-Chem is able to reproduce FTIR measurements at the mid-latitudinal sites, underscoring the impact of the North American oil and gas development on the current C _2 H _6 abundance. Finally we estimate that the North American oil and gas emissions of CH _4 , a major greenhouse gas, grew from 20 to 35 Tg yr ^−1 over the period 2008–2014, in association with the recent C _2 H _6 rise.
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