Methane reductions, ‘climate neutrality’, and choosing the adequate metric for emissions accounting under the Paris Agreement
This briefing provides an overview of the non-CO2 GHG reductions needed, relevant definitions under the Paris Agreement and issues with the “climate neutrality” concept, as well as the implications of different metrics to relate non-CO2 GHGs to CO2.
Achieving the Paris Agreement goal of limiting global warming to 1.5°C requires deep and sustained emission reductions in all greenhouse gases (GHGs) and a balance in emissions and removals resulting in net zero emissions. Frequently, the term “climate neutrality” is used when referring to net zero goals. While the term is ambiguous and can be used in misleading ways, it is best understood as net zero GHGs as by the Paris Agreement. As GHGs differ in how they impact the climate and temperature change, scientists and policymakers use simple accounting measures called metrics to compare and aggregate their effects. In international and national climate policy, the metric must be consistent with the choice that informed the Paris Agreement: the Global Warming Potential over a time horizon of 100 years (GWP100).