Abstract

Production and use of halocarbons (halogenated hydrocarbons) saw explosive growth after the Second World War for use as refrigerants (including air conditioning and industrial refrigeration), solvents, and aerosol propellants. Within decades after their mass introduction, they were implicated in the destruction of Earth's protective ozone layer, concerns over which prompted an international effort to phase out largescale use of the most problematic halocarbon classes, namely chlorofluorocarbons (or CFCs) and hydrochlorofluorocarbons (or HCFCs), under the Montréal Protocol. However, the non-chlorinated hydrofluorocarbon (or HFC) alternatives that were developed to replace CFCs and HCFCs have proved to be exceptionally effective greenhouse agents and historically have been underreported in the ongoing discussions around climate change mitigation. Recent concerns gathering around their increasing abundance in the atmosphere have prompted increased government scrutiny and regulation, resulting in the 2016 Kigali Amendment to the Montréal Protocol recently ratified by the United States. Despite the concerted international effort currently underway to curtail the manufacture and consumption of the most environmentally impactful halocarbons, there have been several reports concerning discrepancies between measured atmospheric abundances and reported inventories of select halocarbon species that have defied expectations.