Revisiting global fossil fuel and biofuel emissions of ethane

Abstract Recent measurements over the Northern Hemisphere indicate that the long‐term decline in the atmospheric burden of ethane (C 2 H 6 ) has ended and the abundance increased dramatically between 2010 and 2014. The rise in C 2 H 6 atmospheric abundances has been attributed to oil and natural gas extraction in North America. Existing global C 2 H 6 emission inventories are based on outdated activity maps that do not account for current oil and natural gas exploitation regions. We present an updated global C 2 H 6 emission inventory based on 2010 satellite‐derived CH 4 fluxes with adjusted C 2 H 6 emissions over the U.S. from the National Emission Inventory (NEI 2011). We contrast our global 2010 C 2 H 6 emission inventory with one developed for 2001. The C 2 H 6 difference between global anthropogenic emissions is subtle (7.9 versus 7.2 Tg yr −1 ), but the spatial distribution of the emissions is distinct. In the 2010 C 2 H 6 inventory, fossil fuel sources in the Northern Hemisphere represent half of global C 2 H 6 emissions and 95% of global fossil fuel emissions. Over the U.S., unadjusted NEI 2011 C 2 H 6 emissions produce mixing ratios that are 14–50% of those observed by aircraft observations (2008–2014). When the NEI 2011 C 2 H 6 emission totals are scaled by a factor of 1.4, the Goddard Earth Observing System Chem model largely reproduces a regional suite of observations, with the exception of the central U.S., where it continues to underpredict observed mixing ratios in the lower troposphere. We estimate monthly mean contributions of fossil fuel C 2 H 6 emissions to ozone and peroxyacetyl nitrate surface mixing ratios over North America of ~1% and ~8%, respectively.