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Why methane should be treated differently compared to long-lived GHGs



Michelle Cain University of Oxford • United Kingdom

Learning Objectives

  1. How methane differs from other greenhouse gasses?
  2. Why are current emission metrics incorrectly assessing global warming?
  3. How can this identify adequate strategies to limit global warming? 

Take home messages

Reduction of CO2 emissions is key; the latter is a long-lived gas that rapidly accumulates in the atmosphere due to the combustion of fossil fuels, which took millions of years to form.

The usual reporting of greenhouse gasses as CO2-equivalents, without mentioning of what proportion is from which gas and the, generates a misleading picture.

Methane attracts attention because of its potency, but behaves as a flow rather than stock pollutant; its impact is overestimated by the current methodology (global warming potential, GWP)

Methane emissions do not have to reach net zero to have “net zero warming” or “climate neutrality”, because constant emissions do not contribute to new global warming.

The new GWP* metric provides a better comparison, more accurately reflecting warming and combining short- and long-term effects. 

Current policies presuppose that methane has a permanently worsening effect on the climate, while GWP* provides agriculture with a more reasonable framework to reduce its impact.

Because of the warming intensity and short life of methane, its reduction could provide a rapid cooling effect leading to a new equilibrium. 

There is potential for methane reduction from fossil fuels, wetlands, and related to better livestock management, which does not necessarily have to compromise the generation of valuable nutrition from animal-source foods. 

Further information

and additional resources are accessible thought the research papers Allen, et al. 2016, Allen, et al. 2018, and the Oxford Martin Programme on Climate Pollutants briefing.