Q800. What factors could have influenced greenhouse gas trends?

A800. In general, observed trends in greenhouse gas totals presented in GHGRP data are due to changes in data reported by facilities. However, in a few cases, changes to methods facility’s use to determine their greenhouse gas data has had an impact on observed trends.

EPA has corrected for a change in the GWPs used by reporters to determine their GHG quantities. Click here to learn more.

For fluorinated gas producers (Subpart L) reporters have not been required to submit annual emissions totals by GHG, but instead reported total GHG emissions in metric tons of carbon dioxide equivalent. 2011-2012 reporting was done using a different set of global warming potentials than was done for 2013. Hence reported emissions from 2013 are not directly comparable to those from prior years.

In the pulp and paper industry (Subpart AA), a change in the emission factors for methane and nitrous oxide as part of the 2013 technical corrections package led to a X% decline in reported emissions.

Among suppliers of natural gas and natural gas liquids (Subpart NN) minor changes were made to the default emission factors for 3 NGLs and natural gas. None of these changes had more than an X% change on reported emissions. However the default emission factor for ethane was reduced by X% and the reported CO2 associated with this product was reduced to the same degree.