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Abstract - Chloroﬂuorocarbons (CFCs) are the primary cause of ozone depletion, and they also contribute to global climate change. With the global phaseout of CFCs and the coming phaseout of hydrochloroﬂuorocarbons (HCFCs), the substitute hydroﬂuorocarbons (HFCs) are increasingly used. While CFCs were originally used mainly in applications5 such as spray cans and were released within a year after production, concern about the ozone layer led to reductions in rapid-release applications, and the relative importance of slower-release applications grew. HFCs are now mainly used in refrigerators and air-conditioners (AC) and are released over years to a decade after production. Their containment in such equipment represents banks, which are building up as production grows. A key ﬁnding of our work is that the increases of HFC banks represent a substantial unseen commitment to further radiative forcing of climate change after production of the chemicals ceases. We show that earlier phaseouts of HFCs would provide greater beneﬁts for climate protection than previously recognized, due to the avoided buildup of the banks. If, for example, HFC production were to be phased out in 2020 instead of 2050, not only would about 91–146GtCO2eq of cumulative emis- sion be avoided from 2020 to 2050, but an additional bank of about 39–64GtCO2eq is also avoided in 2050. Choices of later phaseout dates lead to larger commitments to climate change unless growing banks of HFCs from millions of dispersed locations are collected and destroyed.
Velders, G.J.M., S. Solomon, & J.S. Daniel (2013) Growth of climate change commitments from HFC banks and emissions, Atmospheric Chemistry and Physics 13:32989-33012.