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Present Global Warming (PGW): An Intuitive Single Scaling Factor to Compare Short Lived Climate Pollutants

Qualitatively, it is well understood that methane is a potent greenhouse gas. However, quantitatively describing methane’s potency has proven challenging. Methane traps more heat than carbon dioxide while in the atmosphere, but methane resides in the atmosphere for less time than carbon dioxide. Thus, quantifying the potency of methane requires balancing short- and long-term effects. Traditionally, that balance is struck by integrating effects over a specified period of time, typically 20 years or 100 years. The resulting metric, referred to as the Global Warming Potential (GWP), is ubiquitous, but so are its criticisms. In particular, using the GWP requires making a typically arbitrary selection between two artificial choices, and the resulting choice has a factor of three effect on the quantification of methane’s potency. Here we introduce a new metric, Present Global Warming (PGW), to quantify methane’s potency. Like GWP, PGW quantifies the potency of methane relative to carbon dioxide by a single multiplicative factor, for better and for worse. Unlike GWP, PGW balances short- and long-term effects in an intuitive selection between familiar choices, and the resulting choice has only a 30% effect on the quantification of methane’s potency. We propose that PGW can considered instead of GWP for some future applications.

Drew Pomerantz is an Energy Transition Technology Advisor at Schlumberger, based in Boston, Massachusetts. He focuses on new technologies that reduce direct greenhouse gas emissions from the upstream and midstream oil and gas industry, particularly novel methods to detect fugitive methane emissions. Drew graduated from Stanford University with a PhD in chemistry in 2005 and has co-authored 100 peer-reviewed publications and 25 granted US patents. He founded the Boston chapter of the Society of Petrophysicists and Well Log Analysts (SPWLA) and currently serves as an associate editor for the technical journals "Petrophysics" and "Energy & Fuels".

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