{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"e82e9f15f4ddf79d4fd4fbed60584d2248dd0ce1852981e39cc6cec28937b038","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"555e04b90e3b7f49634a6914b7d3876fbfc9c7719538925cb24f54c2f96f1bff","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"earth.amoc-ice-tipping.amoc-threshold","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"The Atlantic meridional overturning circulation (AMOC, the ocean conveyor carrying warm surface water north) can in theory switch to a weak state if the North Atlantic gets too fresh. Nobody knows how much warming or meltwater would cause that switch.","posed_since":"1961","precise":"Determine whether the present AMOC (about $17\\,\\mathrm{Sv}$ at $26.5\\,\\mathrm{N}$, $1\\,\\mathrm{Sv} = 10^{12}\\,\\mathrm{cm}^3/\\mathrm{s}$) is bistable and, if so, the critical North Atlantic freshwater flux or global warming level at which the strong state disappears, including the timescale of the transition. An answer is a threshold value with uncertainty from models whose salt-advection feedback and mean salinity biases are constrained by observations.","problem_ref":null,"references":"","settled_by":"Observationally constrained estimates of the freshwater transport by the AMOC at the southern Atlantic boundary combined with bias-corrected coupled models that locate the bifurcation.","status_note":"Drijfhout et al. 2025 (Environmental Research Letters) found northern overturning shuts down after 2100 in extended high-emission CMIP6 runs, while Baker et al. 2025 (Nature) found wind-driven Southern Ocean upwelling keeps a weakened AMOC running under extreme forcing.","title":"At what warming or freshwater input does the AMOC collapse?","topic_ref":"7fc551459998c7e7a33c78a6d1d9264023c488edce1886a95542649f021e0b20"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a7c813dfa7325cf1402b570b8e3d1231ba52083802ff8b565aed65341f2af543","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c82ff75fd9ece09ed29f348a9904a1c084c8c7663334ad44f78645408a107474","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"_iDsldwhfFYwOyux3Xzm_PXPeDNI8auD_Us_B-uD8KuA3ncbL98kgbzxgO_flc63W2oXIx1rOZ3pqztlVzV1Cg"},"schema":"pubphys.envelope/1"},"record_hash":"a7c813dfa7325cf1402b570b8e3d1231ba52083802ff8b565aed65341f2af543","leaf_index":1285}