Q799. What are the global warming potentials (GWPs) used in publication of GHGRP data?

A799. See Table A-1 for the complete list of chemical-specific and default GWPs used to calculate carbon-dioxide equivalent (CO₂e) under the GHGRP. Most of the chemical-specific GWPs are drawn from the Intergovernmental Panel on Climate Change’s (IPCC) Fourth Assessment Report (AR4), but the chemical-specific GWPs for some fluorinated GHGs (those that did not have GWPs in AR4) are drawn from the IPCC Fifth Assessment Report (AR5).  The default GWPs for the various groups of fluorinated GHGs are based on both AR4 and AR5 GWPs for chemically similarly fluorinated GHGs.  All GWPs are calculated over a 100-year time horizon.

Effective reporting year 2014, the EPA revised Table A-1 to add GWPs for fluorinated GHGs and fluorinated heat transfer fluids (HTFs) that previously did not have GWPs.  Because emissions of fluorinated GHGs and HTFs without GWPs generally did not count toward CO₂e totals, this change has increased the completeness and accuracy of the CO₂e emissions calculated and reported by suppliers and emitters of fluorinated GHGs and HTFs.

To present a consistent time-series, EPA has provided re-calculated prior year GHG totals.  These re-calculations do not affect the raw data submitted by facilities.