Projecting future HFC-23 emissions

Abstract

A Reference Case (RC) scenario for emissions of HFC-23 from co-production during HCFC-22 manufacture over the next 25 years 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 atmospheric composition and radiative forcing might change with and without additional efforts to constrain HFC-23 emissions. <br></br> 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 &sim;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. <br></br> 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.