ArticleProceedings of the National Academy of Sciences of the United States of America2022
The case and context for atmospheric methane as an exoplanet biosignature.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 9 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
9 citing papers in PubMed.
- Carbon distribution in planet Mercury from magma ocean evolution to graphite crust and core composition.Nature communications · 2026Article
- A hidden pattern? Common polyextremophilic microbial adaptations in Icy Moon analog environments.Frontiers in astronomy and space sciences · 2026Article
- Redox chemistry of early Earth and the origin of life.Communications chemistry · 2026Review
- Evolution and Observable Properties of Rocky Planet Atmospheres.Space science reviews · 2026Review
- Prospects for detecting signs of life on exoplanets in the JWST era.Proceedings of the National Academy of Sciences of the United States of America · 2025Article
- An Informational-Entropic Approach to Exoplanet Characterization.Entropy (Basel, Switzerland) · 2025Article
- The Impact of Extended COThe Astrophysical journal · 2025Article
- JWST ends game of hide and seek with methane.Nature · 2023Article
- Synergies Between Venus & Exoplanetary Observations: Venus and Its Extrasolar Siblings.Space science reviews · 2023Review
Corrections and comments
- Erratum issued
Authors and funding
5 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Methane has been proposed as an exoplanet biosignature. Imminent observations with the James Webb Space Telescope may enable methane detections on potentially habitable exoplanets, so it is essential to assess in what planetary contexts methane is a compelling biosignature. Methane’s short photochemical lifetime in terrestrial planet atmospheres implies that abundant methane requires large replenishment fluxes. While methane can be produced by a variety of abiotic mechanisms such as outgassing, serpentinizing reactions, and impacts, we argue that—in contrast to an Earth-like biosphere—known abiotic processes cannot easily generate atmospheres rich in CH4 and CO2 with limited CO due to the strong redox disequilibrium between CH4 and CO2. Methane is thus more likely to be biogenic for planets with 1) a terrestrial bulk density, high mean-molecular-weight and anoxic atmosphere, and an old host star; 2) an abundance of CH4 that implies surface fluxes exceeding what could be supplied by abiotic processes; and 3) atmospheric CO2 with comparatively little CO.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.