Projecting future HFC-23 emissions

Abstract

Abstract. A Reference Case (RC) scenario for emissions of HFC-23 from co-production during HCFC-22 manufacture over the next 25 yr is presented. Offered as a template rather than a prediction, this model projects current production practices and existing abatement frameworks to yield insights into how the atmosphere might evolve with and without additional efforts to constrain HFC-23 emissions. Assuming that no additional abatement measures are implemented, emissions for year 2035 in this Reference Case would rise to 24 ktonnes yr−1, (cf., 8.6 ktonnes yr−1 in 2009), the atmospheric abundance of HFC-23 would rise to 50 ppt, which is a 121 % increase over the 2009 observed abundance, and HFC-23 would be expected to contribute a radiative forcing of 9 mW m−2 (cf., 4 mW m−2 in 2009). Under such a scenario, the HFC-23 emission growth rate would be a continuation of the historical trend of ~0.2 ktonnes yr−2 until 2030, after which the growth is projected to quadruple as the Montreal Protocol phase-out of HCFC production for dispersive use concludes and HFC-23 thermal decomposition in the projects of the Clean Development Mechanism (CDM) comes to a scheduled end while growth in the production of HCFC-22 for feedstock use continues to climb with projected GDP growth. Two opposite variations regarding the future renewal of CDM projects are examined for their impact on projected emissions and abundance, relative to the Reference Case scenario.