Climate negotiators head to Turkey next month for the United Nations annual climate summit, following a troubling U.N. report issued just two months prior that warned the world has a narrowing window to restrict global warming to safe thresholds. The upcoming discussions at the Conference of the Parties, or COP, are set to confront a central challenge: slashing methane pollution, fast, to bring planet-warming gases under control.
Global Methane Pledge Commitments and GWP* Discrepancies
A new analysis published Oct. 29 and commissioned by Greenpeace International examines a method for measuring methane known as global warming potential*, or GWP*. Researchers utilized modeling from the consultancy group Cerulogy to analyze the top 10 livestock-exporting countries that committed to cutting methane emissions 30 percent by 2030 under the Global Methane Pledge. The analysis compared how emissions reporting for beef powerhouses like Brazil and the United States would look using traditional GWP100 metrics versus GWP* accounting.
The modeling indicates that these livestock-heavy nations could cut actual methane emissions by just 0.6 percent in 2030 compared to 2020 levels, yet still report a 30 percent reduction under GWP*. Under traditional GWP100 accounting, meeting the 30 percent Global Methane Pledge target would require these countries to collectively cut the equivalent of 640 million metric tons of carbon dioxide emissions in 2030. However, by applying GWP*, the same countries could claim 898 million metric tons of negative carbon dioxide emissions, creating a gap of 1,538 million metric tons between reported figures and atmospheric reality.
Did You Know? About 10 years ago, scientists at the University of Oxford developed GWP* to equate emission rates of short-lived climate pollutants to single pulses of carbon dioxide, reflecting that methane does not have the same cumulative effect as carbon dioxide and that methane emitted from cow belches originates from vegetation that originally removed carbon dioxide from the atmosphere.
Scientific Debate Over Livestock Emissions Accounting
Greenhouse gas measurements have historically been standardized as carbon dioxide equivalents across 20- and 100-year periods—known respectively as GWP20 and GWP100—pursuant to the UN Framework Convention on Climate Change. While carbon dioxide persists for centuries, methane causes an initial burst of warming before degrading after about 12 years.
Earlier this year, 42 prominent climate scientists warned that GWP* calculations allow industries and countries to set no-additional-warming targets that threaten essential methane reductions. Last year, New Zealand became the first country to set a no-additional-warming target based on GWP* accounting principles, where the livestock industry accounts for nearly half of the country’s greenhouse gas emissions.
Expert Insight: The adoption of GWP* by livestock-heavy economies illustrates how specialized accounting frameworks can alter reported climate progress. As negotiators prepare for the summit in Turkey, the tension between accurate atmospheric tracking and industry-backed accounting baselines remains a primary policy hurdle.
Food Category Comparisons Using GWP20 and GWP100
In a separate study published Oct. 11 in the journal Frontiers in Sustainable Food Systems, researchers from the University of California, Los Angeles, analyzed food emissions across 16 categories and 222 items. The authors compared GWP20 and GWP100 metrics to evaluate how food choices impact atmospheric warming over different time horizons. They discovered that while most foods showed similar emission impacts across both metrics, livestock-based foods—particularly beef—produced much higher emissions when evaluated over a 20-year timeframe.
Using GWP100, beef-based meals produced about 3,500 grams of carbon dioxide equivalent, whereas applying GWP20 pushed those same meals to more than 7,000 grams of carbon dioxide equivalent. The researchers suggest that policymakers and climate negotiators should rely on more than one metric in analyzing the climate impact of the world’s eating patterns, noting that 100-year averages smooth out the potency of methane.
Compare GWP* and GWP100 Metrics
What is GWP* and how does it differ from GWP100?
Developed about 10 years ago at the University of Oxford, GWP* equates emission rates of short-lived climate pollutants like methane to single pulses of carbon dioxide, assuming a steady climb in emissions won’t cause additional warming because methane degrades relatively quickly. GWP100 evaluates greenhouse gases over a 100-year time frame.
How does the Greenpeace report characterize livestock emissions reporting in the United States?
According to the findings of the Greenpeace study, the American livestock sector could report 218 million metric tons of negative carbon dioxide emissions by 2030, even though the industry will actually continue to generate 178 million metric tons of emissions that year.
Which country was the first to adopt GWP* accounting for national targets?
New Zealand became the first country to set a no-additional-warming target based on GWP* accounting principles last year, where the livestock industry accounts for nearly half of the country’s greenhouse gas emissions.
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