California Tightens Restrictions On High-Impact Short-Lived Climate Pollutants

STP, 11 October 2016

Attempts to reduce greenhouse gas (GHG) emissions are more complex than they first appear.  Reports in the mass media tend to focus on carbon dioxide (CO₂).  The United Nations Framework Convention on Climate Change (Framework Convention) focuses primarily on six GHGs, including CO₂ as well as methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride (SF₆).

Climate change scientists have identified hundreds of GHGs, with widely varying sources, relative contributions to climate change (numerical ‘global warming potential (GWP),’ where CO₂ is defined as 1.0), and total contribution based on emitted volumes.  California has been a global leader in climate change prevention initiatives, with programs addressing widely varying sets of GHGs and sources.

On September 19, California’s Governor Jerry Brown signed legislation requiring important additional steps to manage ‘short-lived climate pollutants (SLCPs)’ that have high GWPs.  Earlier studies estimate that these chemicals account for about 12% of net climate change effect of all GHGs emitted in the state, so significant reductions in these categories could make a meaningful difference in statewide emissions – and if replicated could provide comparable reductions in other jurisdictions on a much wider scale.