Abstract. Atmospheric non-methane hydrocarbons (NMHCs) play an important role in the
formation of secondary organic aerosols and ozone. After a multidecadal
global decline in atmospheric mole fractions of ethane and propane – the
most abundant atmospheric NMHCs – previous work has shown a reversal of
this trend with increasing atmospheric abundances from 2009 to 2015 in the
Northern Hemisphere. These concentration increases were attributed to the
unprecedented growth in oil and natural gas (O&NG) production in North
America. Here, we supplement this trend analysis building on the long-term
(2008–2010; 2012–2020) high-resolution (∼3 h) record of
ambient air C2–C7 NMHCs from in situ measurements at the Greenland
Environmental Observatory at Summit station (GEOSummit, 72.58 ∘ N,
38.48 ∘ W; 3210 m above sea level). We confirm previous findings
that the ethane mole fraction significantly increased by +69.0 [+47.4,
+73.2; 95 % confidence interval] ppt yr−1 from January 2010 to
December 2014. Subsequent measurements, however, reveal a significant
decrease by −58.4 [−64.1, −48.9] ppt yr−1 from January 2015 to December
2018. A similar reversal is found for propane. The upturn observed after
2019 suggests, however, that the pause in the growth of atmospheric ethane
and propane might only have been temporary. Discrete samples collected at
other northern hemispheric baseline sites under the umbrella of the NOAA
cooperative global air sampling network show a similar decrease in 2015–2018
and suggest a hemispheric pattern. Here, we further discuss the potential
contribution of biomass burning and O&NG emissions (the main sources of
ethane and propane) and conclude that O&NG activities likely played a
role in these recent changes. This study highlights the crucial need for
better constrained emission inventories.
Long-term ambient air-stable cubic CsPbBr3 perovskite quantum dots using molecular bromine
