Generated Summary
This perspective, published in Environmental Research Letters, examines the claims of climate neutrality made by the livestock sector. The study investigates the use of the Global Warming Potential (GWP*) metric and its application in the livestock sector. The research approach involves analyzing existing studies and claims related to climate neutrality within the livestock industry, particularly in developed nations. The methodology includes a critical examination of the term ‘climate neutrality,’ the GWP* metric, and how these claims align with the Paris Agreement. The scope encompasses the climate impact of livestock production, focusing on methane emissions and their implications for climate policy and public debate. The study aims to reveal the potential misrepresentation of sector-level methane mitigation and its consequences for climate goals.
Key Findings & Statistics
- The National Cattlemen’s Beef Association in the US claims to be able to reach climate neutrality for their beef production by 2040.
- A UNECE seminar claimed the US dairy industry can reach climate neutrality by 2041, despite remaining a significant source of greenhouse gases (GHGs).
- Place et al. [3] state that the US dairy industry could reach climate neutrality by 2050 from annual methane (CH4) emission reductions of 1%-1.5% to that point.
- Liu et al. [4] declare that some US livestock sectors are already part of a climate solution’.
- Ridoutt [5, 6] argues that Australian sheep production is already climate neutral despite its rising CO2 emissions.
- Del Prado et al [7] claim that European dairy goat and sheep production is already climate neutral.
- Ridoutt et al [8] state that Australian lamb currently has a ‘negative climate footprint’.
- Methane is responsible for warming of approximately 0.5 °C, compared to 0.8 °C caused by carbon dioxide (CO2).
- Agriculture is the largest source of methane.
- In IPCC scenarios limiting the increase in global surface temperature to 2 °C, global CH4 emissions are reduced by around 37% (20%-60%) by 2040, compared to 2019 levels.
- In 1.5 °C scenarios with no or limited overshoot, global CH4 emissions fall 44% (31%-63%) by 2040.
- With overshoot of the 1.5 °C target now very likely [18], the goal of merely stabilizing the temperature impact of major emitters of CH4 is increasingly misaligned with the temperature goal of the Paris Agreement.
Other Important Findings
- The term ‘climate neutral’ is used by the United Nations Organisation, defined as net-zero GHG emissions, expressed in units of CO2 equivalence (CO2e).
- The climate neutrality claims depend on a subtle shift in the definition from net-zero GHG emissions (net-zero CO2e) to no additional warming impact (net-zero CO2we).
- The established means of standardizing different GHGs into one CO2-equivalent (CO2e), representing the warming caused by CO2 over a one-hundred year period (global warming potential, GWP100), does not differentiate between long-lived climate pollutants (LLCPs) and short-lived climate pollutants (SLCPs).
- Global temperature increases linearly with cumulative emissions of LLCPs, such as CO2, whereas changes in the rate of emissions of SLCPs, such as CH4, largely determine their contribution to further warming.
- GWP* accounts for the effect of changes in the rate of SLCP emissions on warming over time.
- The claims of climate neutrality are not permanent, and GWP* shows that to maintain a state of no increase in temperature requires continued reductions in CH4 emissions.
- Article 2 of the Agreement establishes a goal for the global community to limit global warming to well below 2°C compared to the pre-industrial period and to pursue efforts to achieve a 1.5 °C limit.
- Article 4 states the ambition to balance anthropogenic emissions and removals of GHGs in the second half of this century, based on equity and in the context of sustainable development.
- The policymakers who wrote the Agreement text based this aspiration on emission pathways aggregated using GWP100; this GHG balance has been adopted by governing organizations as net-zero CO₂e emissions.
- GWP* to justify a sub-global goal of no additional warming does not go far enough for some sectors, and is also inequitable.
- The climate neutrality outcome in Place et al [3] differs from that expected by the makers of GWP*.
Limitations Noted in the Document
- The study focuses on the livestock sector in developed nations, limiting the generalizability of the findings to other regions or sectors.
- The analysis relies on existing studies and claims, which may have inherent biases or limitations in their methodologies or data.
- The study acknowledges the complexity of climate metrics and the ongoing debate surrounding them, which may influence the interpretation of results.
- The reliance on the GWP* metric, which is still under development, may introduce uncertainties or limitations in assessing the climate impact.
- The claims of climate neutrality often do not consider the entire life cycle of the livestock sector, potentially overlooking other significant GHG emissions.
- The study’s conclusions may be limited by the scope of the Paris Agreement and its focus on temperature stabilization.
Conclusion
The studies in table 1 demonstrate a misinterpretation of the climate impact of livestock production. The claims of climate neutrality are temporary and are not aligned with the broader objectives of the Paris Agreement. The use of GWP* is valuable, especially when used with CO2e for analyzing the global consequences of changes in global greenhouse gas emissions. However, when it’s applied at the sectoral level, it has its limitations as a guide to effective mitigation of GHGs. The ambition of the Paris Agreement is clear: to halt global warming (Article 2) by achieving net-zero GHG emissions (Article 4), all while supporting sustainable development (Article 6). The shift to the term ‘climate neutrality’ has created a loophole for the exploitation of inconsistencies between temperature stabilization and net-zero emissions. This sectoral-level application of GWP* may trade Article 2 for Article 4. This approach risks a misstep in policy action if the metric is changed from GWP100 to GWP* while maintaining the same timeline for GHG balance. It is now critical that policymakers act quickly to adopt national and sectoral mitigation strategies consistent with the Paris Agreement. To quote the authors, ‘We conclude that the studies in table 1 have a distorted understanding of the climate impact of livestock production.’