Two Carbon Co-Conspirators Need to Be Stopped to Tackle Climate Change

This policy brief argues that the current reliance on a single 100-year metric for greenhouse gas emissions obscures the distinct warming impacts of methane and carbon dioxide. The author advocates for a "multi-basket" approach with separate targets and dual metrics to address both short-term and long-term climate risks, asserting that simultaneous mitigation of both pollutants is essential to meet global temperature targets and reduce climate overshoot.

• Methane and carbon dioxide are the two primary drivers of global warming, with methane acting as a "super pollutant" due to its intense near-term warming effect. While carbon dioxide persists for centuries, methane has a shorter lifetime of ten to twelve years but is significantly more potent in the short term, effectively wrapping the planet in more than 80 blankets compared to carbon dioxide's single blanket.
• The current standard for emissions accounting uses a 100-year timeframe and a single carbon dioxide-equivalent (CO2e) metric known as Global Warming Potential (GWP), which the author claims is a political rather than scientific decision. This approach masks methane's short-term impact and creates ambiguity that hides the distinct warming effects of different pollutants.
• To effectively manage climate risks, the document proposes adopting dual metrics—specifically reporting the 20-year metric (GWP20) alongside the 100-year metric (GWP100)—and mandating that countries set separate nationally determined contributions (NDCs) for methane and carbon dioxide.
• Simultaneous mitigation of methane and carbon dioxide is critical for preserving Arctic summer sea ice and reducing climate overshoot. A dual metric approach aligned with the Global Methane Pledge—targeting a 30% reduction below 2020 levels by 2030—could reduce climate overshoot by a factor of seven compared to a single CO2 metric.
• Atmospheric concentrations of both pollutants have reached record levels. As of June 2024, CO2 concentrations were 427 ppm, a 54% increase from pre-industrial times. As of April 2024, methane concentrations reached 1932 ppb, nearly tripling since pre-industrial times, with significant annual increases of 10-18 ppb occurring since 2020.

APA

RMI (2024). Two Carbon Co-Conspirators Need to Be Stopped to Tackle Climate Change. https://rmi.org/resources/two-carbon-co-conspirators-need-to-be-stopped-to-tackle-climate-change/

Chicago

RMI. Two Carbon Co-Conspirators Need to Be Stopped to Tackle Climate Change. 2024. https://rmi.org/resources/two-carbon-co-conspirators-need-to-be-stopped-to-tackle-climate-change/.

Wikipedia

{{cite report |author=RMI |title=Two Carbon Co-Conspirators Need to Be Stopped to Tackle Climate Change |date=17 September 2024 |url=https://rmi.org/resources/two-carbon-co-conspirators-need-to-be-stopped-to-tackle-climate-change/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2024two, author = {{RMI}}, title = {{Two Carbon Co-Conspirators Need to Be Stopped to Tackle Climate Change}}, institution = {RMI}, year = {2024}, month = sep, url = {https://rmi.org/resources/two-carbon-co-conspirators-need-to-be-stopped-to-tackle-climate-change/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }