{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"98c205ef2283043717ccd83a94d4b6ae6a44f5337dd46e6411c7cf1206c623d4","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","de14d77737ffb9790d6480718cfa16c38986bff012cc7d39ca19faa6681cb10b"],"salt":"27c77e7f69ccf7853e8cdb462bf109296e3603bf400bd2fba0628767e10ac0c6","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":"2","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: $\\mathrm{CO_2}$-$\\mathrm{H_2}$ or $\\mathrm{CO_2}$-$\\mathrm{CH_4}$ 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":"de14d77737ffb9790d6480718cfa16c38986bff012cc7d39ca19faa6681cb10b","references":"","settled_by":"A climate scenario whose required $\\mathrm{H_2}$ or $\\mathrm{CH_4}$ 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":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"bc6f6f376882912ba3952219e1484b3137b1e90a970fa7de9f905d276f6ae0ed","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"e35d2426d73229aaa36932afb8c45504a88db60681093acf181191248020c656","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"KbY4JSzdlDMx54rtk82E0FdmepmUkuKGQ_hK3fas_tTCj5Kyx-mq-7Xd_BlmAsPjHuB_YhnTeqGy88D_lgqBCQ"},"schema":"pubphys.envelope/1"},"record_hash":"bc6f6f376882912ba3952219e1484b3137b1e90a970fa7de9f905d276f6ae0ed","leaf_index":3218}