The Global Warming Potential is Inconsistent with the Physics of Climate
Change and Misrepresents the Effects of Policy Interventions
Abstract
The Global Warming Potential (GWP) is a widely used single-number metric
used to compare the climate change effects of various greenhouse gases.
Although GWP has an established role in international climate
agreements, it is unphysical, unintuitive, arbitrary, ignores the time
dependence of emission sources, and is in some cases misleading. The
same doubts have been expressed by the convening lead author of the
relevant chapter in the First Assessment Report of the Intergovernmental
Panel on Climate Change, in which GWP was introduced. GWP and the
related CO2-equivalent methodology have no place in describing the
effects of climate change mitigation strategies beyond a 20 year
horizon. An important element of sound policy making is the quantitative
analysis of policy interventions. This work argues for the broader use
of temperature change trajectories in educating policymakers and the
public about greenhouse gas control. Modeling tools include general
circulation models, related reduced complexity models, and simpler
models of global mean temperature change. Examples are presented
illustrating the misleading nature of GWP and the CO2-equivalent
methodology. These include the greenhouse gas impacts of (1) single year
and multiyear emissions of methane, (2) natural gas and coal use in the
electric power sector, (3) pipeline and LNG transport of natural gas,
(4) natural gas flaring, and (5) livestock herd reduction. Responding to
climate change is likely to require global investments measured in
trillions of dollars. Clear and accurate communication among and between
scientists, policy makers. and the general public is essential. GWP is a
crude, inaccurate tool that and the general public is essential. GWP is
a crude, inaccurate tool that played a constructive role in the
formulation of international agreements. Using better modeling tools can
help make climate policy discussions more scientifically rigorous while
demystifying the criteria upon which policy choices are made.