Gwp*- An Inappropriate And Dangerous Measure Of Livestock Methane’s Contribution To Global Warming

Generated Summary

This policy brief strongly advises against the adoption of GWP* (Global Warming Potential Star) as a climate metric for assessing the impact of greenhouse gas emissions, particularly in the context of livestock methane. It recommends maintaining the use of GWP100 (Global Warming Potential over a 100-year period) and GWP20 (Global Warming Potential over a 20-year period) for measuring atmospheric heating caused by greenhouse gases. The brief highlights the risks associated with GWP*, including its potential to allow greenwashing by livestock companies, unfairly reward historical methane emitters, and undermine international efforts to reduce global greenhouse gas emissions. The core argument presented is that GWP* is an inappropriate and dangerous metric because it can distort the true impact of methane emissions, especially from the livestock sector, and can lead to misleading assessments of climate impact by businesses and countries. The document provides detailed comparisons between GWP* and established metrics like GWP100 and GWP20, explaining how GWP* measures changes in warming impact relative to a chosen baseline year, which can be manipulated, rather than the total warming impact of emissions. The briefing aims to provide an understanding of why reducing methane is crucial, why the livestock sector is a major source of methane, and how GWP* can be used to mislead. The document is a policy briefing, and therefore it’s not a research study. The method used involves comparison and contrast between climate metrics, using evidence to explain the differences in the effect the metrics have.

Key Findings & Statistics

• Methane (CH₄) is an extremely powerful greenhouse gas causing about 80 times more warming per kg than carbon dioxide (CO₂) over a 20-year period (GWP20) and on average 27 times more warming than CO₂ over a 100-year period (GWP100).
• The Intergovernmental Panel on Climate Change (IPCC) estimates that methane has contributed an estimated 0.5°C of global warming since 1850-1900, second only to CO₂’s contribution of an estimated 0.75°C warming.
• Methane emissions need to be reduced by at least a third by 2030 to meet the Paris Climate Agreement.
• Methane reductions of at least 47-60% are required by 2050 to stay within 1.5°C of global warming.
• The livestock sector accounts for an estimated 31% of global methane emissions, followed by oil & gas (26%), landfills (14%) and coal mining (11%).
• Massive increases in livestock numbers led to an estimated 332% increase in methane emissions from ruminant livestock between 1890 and 2014.
• Livestock methane emissions are projected to increase by a further 30% by 2050 without policy interventions.
• Reducing EU meat and dairy consumption in line within EU member states’ current nutritional recommendations, and an associated reduction of EU livestock production, would lead to an estimated 29-37% reduction in livestock methane emissions.
• GWP* effectively erases the historical methane emissions of companies through use of a historical baseline.
• A small 15% reduction in livestock corporation Tyson Foods’ methane emissions would be reported under GWP100 and GWP*.
• The US cattle and dairy industry could continue emitting 68-82% of its current methane emissions by 2050, plus all of its current CO₂ and N₂O emissions.
• New Zealand’s livestock sector could continue emitting 76% of its current methane.
• GWP* assigns it a 16x larger global warming impact per tonne of methane emitted than an established source (more than 20 years old).

Other Important Findings

• The briefing suggests maintaining the use of GWP100 (or GWP20) for measuring the atmospheric heating caused by greenhouse gases.
• The adoption of GWP* is likely to allow livestock companies to greenwash their production systems or products as “climate neutral” or “climate negative” while still causing large amounts of emissions.
• GWP* may reward historically high methane emitters (often those in the Global North) while penalizing countries in the Global South for comparatively low methane emissions.
• GWP* could undermine international efforts to reduce global greenhouse gas emissions in line with the Paris Agreement target of 1.5°C.
• The industry’s incentive for pushing GWP* is clear – in most cases, it gives the biggest livestock companies license to continue polluting, rewards them for minor methane reductions, and allows false offsets of CO2 and N₂O.
• Methane is also more short-lived in the atmosphere than CO₂ – with an average lifetime of approximately 12 years, it gradually breaks down into CO₂ and H₂O meaning its warming power declines, although not completely.
• GWP* is thus a useful model for narrowly measuring the change in warming impact of methane emissions over time at global level, but is totally inappropriate as a metric for measuring progress on climate impact by businesses and countries.
• The adoption of GWP* lets historical methane emitters continue polluting, in contradiction with the polluter pays principle.
• If a livestock company claims that changes in its methane emissions have a net-cooling impact via the GWP* metric, it can then use these “negative” emissions to offset its own CO2 emissions.
• GWP* would heavily punish small-scale livestock farmers in the Global South if they increase their methane emissions from a low baseline.
• For high methane-emitting countries, the perverse impacts of GWP* are even more dangerous.

Limitations Noted in the Document

• The briefing focuses primarily on the impact of GWP* in the context of the livestock industry, and doesn’t comprehensively cover the implications in other sectors.
• The policy brief may not fully address all the nuances of climate metrics.
• The briefing relies on the assumption that GWP100 and GWP20 are more appropriate metrics, which may be challenged by other perspectives.
• The document may not fully explore alternative climate metrics beyond GWP100 and GWP20.
• The analysis of the effects of GWP* is limited to the scenarios and examples provided in the briefing, potentially overlooking other possible outcomes or situations.

Conclusion

The central argument put forth in this policy brief is that the adoption of GWP* as a climate metric is not only inappropriate but also dangerous, particularly when applied to assess the contribution of livestock methane to global warming. The brief asserts that GWP* can lead to misleading claims of climate neutrality and encourages the continuation of polluting activities by large emitters, specifically within the livestock sector. As the document underscores, GWP*’s focus on the change in warming impact, rather than the total warming impact, allows for the historical methane emissions of companies to be effectively erased through the use of a historical baseline. As a result, large entities can continue to emit substantial amounts of methane and still be portrayed as climate-neutral or even climate-positive by taking minor methane reductions. This approach directly contradicts the polluter pays principle, incentivizing further pollution and potentially undermining global climate goals, like the Paris Agreement target of 1.5°C. Furthermore, the brief highlights that GWP* could unjustly reward countries or companies with a history of high methane emissions while penalizing those with lower initial emissions. This inequitable aspect could exacerbate existing climate injustices, especially for developing nations that are gradually increasing their emissions to support development. The briefing points out that if New Zealand’s farmers cut methane by just 24% by 2050, then this “would offset the warming impact of all the other emissions” – from all economic sectors, not just agriculture – such that “New Zealand could declare itself climate neutral almost immediately, well before 2050, and only because farmers were reducing their methane emissions”, which enables a “free pass to all the other sectors, courtesy of New Zealand’s farmers.” This is a critical issue of this policy brief. The consequence would be to drastically undermine the effect of the reduction that is required, which would have dire outcomes. In conclusion, the policy brief calls for a shift away from GWP* as a primary metric and advocates for maintaining the use of GWP100 and GWP20 alongside increased reporting of individual greenhouse gases to reduce reliance on equivalence metrics. The authors’ final thoughts emphasize the urgency of accurate and transparent climate accounting, particularly within the livestock sector, to ensure effective mitigation efforts and uphold principles of climate justice. They assert that the choices in climate metrics have significant consequences for global warming and the success of efforts to combat it. The authors of this briefing have a very particular set of recommendations. As the authors note, “This briefing strongly advises against the adoption of GWP* as a climate metric – and instead recommends maintaining GWP100 and GWP20 as appropriate metrics.”