Climate Notes: Methane

How cow burps, termite toots, and natural gas are warming the planet

Experimenting with a new, “raw” format of sharing notes on what I’m learning in climate. Feel free to use it if it’s helpful and share any feedback, corrections, or additions you come across.

The Problem

  • For a time horizon of 100 years, CH4 has a Global Warming Potential 28 times larger than CO2. Each molecule is 84x more warming than CO2

  • Methane is responsible for 23% of the global warming produced by CO2, CH4 and N2O in the 20th century.

  • The concentration of CH4 in the atmosphere is 2.5x above pre-industrial levels (750ppb —> 1800)

  • Methane remains in the atmosphere for ~10 years (though exactly how long depends on atmospheric hydroxyl radical levels, of which we don’t have a great way to measure). This makes methane a big lever to reduce warming as reduced emissions —> reduced warming within a decade.

    • Stock v. Flow: Stock gases are long-lived and build up in the atmosphere (e.g. CO2). Flow gases are naturally removed from atmosphere over time (e.g. CH4). Solve the flow problem for methane and you solve the warming problem within the decade.

  • Concern that melting permafrost may contain high levels of methane ("methane bomb") that is emitted as planet heats up and ice caps melt.

  • “Million paper cut” kind of problem: Methane emitters are usually diffuse (manure fields, abandoned mines, municipal landfills) and while the tech isn’t hard (“more plumbing v. rocket science”) requires policy > behavior change > enforcement.

Methane Budget

Opportunities

CH4 warming mitigation represents a potential short-term fix for global warming, as methane traps a lot of heat per molecule but is relatively short-lived. Reducing methane levels can buy us more time to scale up carbon capture. Number of atmospheric molecules you'd need to reduce is much smaller than CO2 (but also far more diffuse)

Questions

  • What prevents us from measuring atmospheric hydroxyl radicals levels?

  • What’s the limiting factor on scaling methane-oxidizing bacteria?

  • Is there a way to create a realtime dashboard of methane emissions attributed to the source based on satellite data?

Resources