{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"42257d1e5cdaca691d8c8e1ff352b4ebe6dc7d7389ce03d015ab9e9d2331301f","created":"2026-10-03T07:18:03Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1697bfad1df94c66194c5a606f57f5abb5ad5c3a2ed676edb38f6278d25efc8f","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"earth.paleoclimate-puzzles.early-mars-warmth","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"About 3.7 billion years ago Mars had river valleys and lakes even though it is farther from a then fainter Sun. Carbon dioxide and water vapour alone do not seem able to warm it enough, so the question is what else did.","posed_since":"","precise":"For Noachian to early Hesperian Mars (about $3.8\\ \\text{to}\\ 3.5\\,\\mathrm{Gyr}$ ago, insolation $\\sim 0.32\\,S_0$ relative to modern Earth) determine whether surface runoff required sustained warm conditions (mean $T$ above $273\\,\\mathrm{K}$) or episodic warming, and identify the forcing: CO2-H2 or CO2-CH4 collision-induced absorption, cirrus clouds, impacts or volcanic outgassing. An answer specifies atmospheric composition, pressure and duration consistent with valley-network and lake-sediment volumes and with surviving carbonate inventories.","problem_ref":null,"references":"","settled_by":"A climate scenario whose required H2 or CH4 sources, surface pressure and warm-period duration match sediment volumes and the measured carbonate and atmospheric-loss record.","status_note":"","title":"What kept early Mars warm enough for rivers and lakes?","topic_ref":"4f250e50d442c2085fd7091e2a80ea67262938b9c04552ef688788b2ebee9449"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"de14d77737ffb9790d6480718cfa16c38986bff012cc7d39ca19faa6681cb10b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"24444129d36c675a4e187d9921f91c13432ab926f6e0a28d96d33bcc3aa18c48","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"sTuhMqBtIImgOqOPNHT-ndJcE8uOrvGUQJQwcwAFMF1GpiVdo4NUNeoJZPuSyQS0FQq8KTl6sloJswiZCNnQCw"},"schema":"pubphys.envelope/1"},"record_hash":"de14d77737ffb9790d6480718cfa16c38986bff012cc7d39ca19faa6681cb10b","leaf_index":1348}