Why are small methane sources underestimated?
Small, diffuse emitters are a bigger climate problem than assumed
Methane is far more powerful than carbon dioxide over short timeframes — about 80 times more effective at trapping heat in the atmosphere — which makes even modest sources important for near‑term warming. New analyses show that attention focused on the largest industrial emitters has left a diffuse background of many smaller sources undercounted. Those small emitters add up: when measurement methods or inventories miss lots of low‑volume leaks, biological sources, or dispersed agricultural and waste sites, the true methane burden can be substantially higher than official tallies suggest.
Researchers point to several practical reasons for the gap between estimates and reality:
- Monitoring bias: regulatory reporting and satellite retrievals are often tuned to detect the largest plumes, and miss many low‑intensity, spatially spread emissions.
- Source complexity: emissions come from varied processes — natural wetlands, small farms, landfills, pipelines and tanks, and fugitive leaks from myriad small facilities — making comprehensive accounting difficult.
- Temporal variability: many sources pulse seasonally or episodically, so short monitoring campaigns can miss large but intermittent releases.
Why it matters
Underestimating these sources weakens climate policy. Targeting only the obvious, high‑volume emitters leaves large, inexpensive mitigation opportunities on the table and can slow progress toward near‑term warming goals. Fixing small leaks, improving waste management, and better protecting and restoring methane‑producing ecosystems could produce fast climate benefits because methane decays relatively quickly in the atmosphere. Improved measurement strategies — combining satellites, aircraft, ground sensors and bottom‑up inventories — are essential to reveal the missing emissions and to prioritize actions that deliver the fastest, most cost‑effective reductions.