Controversy Surrounds New Methane Emissions Metric GWP*

November 15, 2023

Some of the world’s major meat and dairy companies have adopted a new metric called GWP* (pronounced as GWP star) to measure methane emissions, claiming it offers a more accurate assessment of greenhouse gas (GHG) emissions. However, a recent report titled “Seeing Stars” argues that GWP* can be manipulated to downplay emissions and falsely claim climate neutrality.

Understanding GWP* vs. GWP100

Under the 2015 Paris Agreement, the established metric for measuring the global warming potential of gases over a 100-year period is GWP100. This metric focuses on the absolute levels of emissions and compares the warming effect of non-carbon dioxide (CO2) GHGs to an equal amount of CO2. In contrast, GWP* evaluates changes in emissions over decadal timescales rather than absolute levels.

The Manipulative Potential of GWP*

The “Seeing Stars” report, authored by Nicholas D Carter and Nusa Urbancic, highlights how GWP* can be used by high-polluting countries and companies to manipulate emissions data. By setting parameters that alter the baseline year for methane emissions, even minor reductions can be presented as negative emissions or cooling. This can lead to a lack of action in cutting methane emissions.

Case Studies

The report examined emissions reductions for Tyson, a major meat processor, and Fonterra, the largest dairy exporter, using both GWP100 and GWP* metrics. It found that these companies could claim climate neutrality with minimal annual emissions reductions (1.4% and 1.7%, respectively) when using GWP*. This allows them to significantly reduce their reported emissions.

The Impact on Countries

The report also looked at New Zealand, where half of emissions come from agriculture, primarily methane. With a modest 10% reduction in methane emissions, the country could report negative methane emissions using GWP* by 2038.

Industry Lobbying

The researchers discovered evidence of agricultural lobbies pushing for GWP* adoption in various regions, including New Zealand, Ireland, and the United States. Industry groups in the UK and New Zealand jointly urged the IPCC to adopt GWP* for assessing warming impacts in 2020. Ireland’s Department of Agriculture expressed interest in GWP* due to concerns about meeting ambitious emission reduction targets.

Contentions Surrounding GWP*

GWP* has drawn criticism at a global policy level because it can reward historically high-emitting countries and companies for minor emissions reductions from a high baseline. Conversely, it may penalize countries with historically low methane emissions for small increases. The debate centers on whether GWP* accurately represents the climate impact of methane emissions.

Development of GWP*

GWP* was developed in 2016 by Oxford University researchers and introduced at the 24th Conference of Parties (COP24) to the United Nations Framework Convention on Climate Change in 2018. It was proposed as a more accurate system for reporting national methane emissions at the international level.

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