Stringent methane cuts needed to keep warming well-below 2C

Estimated reading time: 5 minutes · Last updated: 1 September 2026

Weber et al. (2026) find that ambitious methane cuts are essential to keep peak warming well-below 2C. Using a simple climate model the authors separate CO2 and methane pathways and show that, under a 2050 global net-zero CO2 trajectory, methane emissions must fall by at least 69% by 2050 relative to 2020 to limit peak warming to 1.7C. The study also finds that under current policy pathways — which project methane rising by around 20% by 2050 relative to 2020 — peak warming would exceed 2C even if CO2 reached net-zero by 2050. Those results change how carbon budgets and net-zero pledges should be framed.

Why CO2-equivalent metrics can hide methane’s short-term impact

Policy and many models commonly convert methane and other greenhouse gases into a single CO2-equivalent number. That conversion is convenient for targets and company reporting but it depends on the metric chosen. GWP20, GWP100 and GWP* each compare methane to CO2 over different time horizons or on different assumptions about rate versus cumulative effects.

GWP20 emphasises near-term warming and therefore makes methane mitigation look urgent. GWP100 spreads methane’s warming over a century and downweights its near-term potency. GWP* uses the rate of emissions, which can make constant methane emissions appear as causing “no additional warming” in some interpretations. Each choice changes how large and urgent methane cuts appear and therefore how they are prioritised in policy and integrated assessment model outputs.

Because integrated assessment models (IAMs) combine gases and typically optimise pathways on cost, they may underrepresent pathways that are not purely cost-effective but that are important for limiting near-term peak warming. The paper’s starting point is that peak warming limits should determine the minimum methane effort compatible with existing CO2 net-zero dates, rather than the other way round.

What Weber et al. (2026) did and the headline numbers

Weber et al. (2026) decouple CO2 and methane in a simple climate model and test combinations of linear emission trajectories starting in 2025. The study maps peak global warming to the year of global net-zero CO2 and the percentage change in methane emissions between 2020 and that year, producing contours of equal peak warming.

The headline finding is that, in a scenario where CO2 reaches net zero in 2050, keeping peak warming near 1.7C requires methane emissions to drop by roughly two-thirds compared with 2020 levels (around a 69% reduction by 2050). If a 2050 net-zero commitment already covers all greenhouse gases, the needed methane cut is about 63% by 2050. The paper further estimates that cutting methane by roughly one-third by 2030 — the ambition of the Global Methane Pledge — would lower peak warming by about 0.15C, and about 0.05C of that benefit could come from measures the International Energy Agency judges to have no net cost.

The model runs further show that if methane emissions remain at 2020 levels and net-zero CO2 is achieved only by 2040 or later, warming would exceed 1.85C. Under a current-policy trajectory that raises methane by around 20% by 2050, peak warming passes 2C even with 2050 CO2 net-zero on the same assumptions.

Implications for carbon budgets and for national targets

Carbon-budget estimates used to set CO2 targets depend on assumptions about concurrent methane cuts. The IPCC’s 2021 assessment and a 2023 Nature study estimated the remaining carbon budget for 2C in 2025 at roughly 1,000-1,150 GtCO2; Weber et al. show those figures rest on assumed methane reductions of about 27-35% by 2050 relative to 2020.

Using GWP* or failing to reduce methane significantly changes the arithmetic: with GWP* the central 2C-compatible CO2 budget drops by about 30%, to roughly 750 GtCO2, and if methane emissions remain unchanged the remaining carbon budget consistent with 1.7C is effectively exhausted, the paper finds. That outcome forces either much faster CO2 cuts or much tougher methane policies.

For policy, the paper’s practical prescription is simple: states and organisations should choose a cap on peak warming first and then calculate the smallest methane cut compatible with their CO2 net‑zero timetable. Few countries currently publish explicit methane targets; the paper highlights Japan, Mexico and South Korea as exceptions. Making methane-specific targets explicit would align mitigation planning with the peak-warming outcomes decisionmakers seek to avoid.

Case for and against stronger methane policy

The bottom line

Weber et al. (2026) reframes the mitigation question: peak-warming limits, not single-number CO2-equivalents, should define the minimum methane effort compatible with a given net-zero timetable. The quantitative consequences are large — for example, a 69% methane cut by 2050 is compatible with 1.7C under a 2050 CO2 net-zero path, while a 20% rise by 2050 pushes peak warming above 2C even with CO2 net-zero in 2050. Policymakers should therefore publish and align explicit methane targets alongside CO2 net-zero dates so that national and corporate plans map to the peak-warming outcomes they intend to avoid.

What to watch

• 2030: assess whether signatories of the Global Methane Pledge achieve around a one-third reduction in methane emissions relative to 2020.
• 2050: check whether methane emissions have fallen by about 69% relative to 2020 under a 2050 CO2 net-zero pathway, or by about 63% where net-zero covers all greenhouse gases.