Popular Climate Change Metric Misleads Policymakers

A widely used metric in policymaking circles uses over-simplified forecasting methods that can lead to costly mistakes. The Global Warming Potential (GWP) metric has significant shortcomings—it is poorly grounded in physics, arbitrarily designed, difficult to understand, overly naïve as a policy driver, and in some cases potentially misleading.

The ISE’s new report, The Global Warming Potential Misrepresents the Physics of Global Warming Thereby Misleading Policy Makers, argues that more scientifically rigorous modeling tools are necessary to augment the GWP.

Mathematical models represent our best hope of optimizing the outcomes of the actions we take today to mitigate climate change. The GWP uses simple numerical multipliers to account for the differing effects of emitting various greenhouse gases into the atmosphere.

Key takeaways:

• The GWP is widely used to compare the climate change effects of various greenhouse gases. Although the GWP has an established role in international climate agreements, it does not describe any specific identifiable impact of greenhouse gas emissions on climate.
  
  
• The GWP is unphysical, unintuitive, arbitrary, ignores the time dependence of emission sources, and is in some cases misleading. Therefore it has no place in describing the effects of climate change mitigation strategies beyond a 20-year horizon.
  
  
• Global mean temperature change trajectories should be the preferred “easy-to-understand” model in educating policymakers and the public about greenhouse gas control, thereby making climate policy discussions more scientifically rigorous while demystifying the criteria upon which policy choices are made. Examples provided include multi-year emissions, venting versus flaring of natural gas, electric power generated by natural gas versus coal, European gas supply by LNG versus pipeline, European electric power by imported gas versus coal, and livestock reduction.

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