Doubling CO₂ raises equilibrium temperature by more than 3 °C.

This is the frozen contract wording. Read the YES and NO tests, the evidence requirements and the undecided cases before taking a position.

Canonical title

Preindustrial Charney climate sensitivity exceeds 3 °C.

Exact hypothesis · technical wording

The global mean surface-air temperature increase at equilibrium after atmospheric CO2 is held at twice its preindustrial concentration exceeds 3 kelvin, with preindustrial ice-sheet geometry, vegetation distribution, land use, other greenhouse-gas concentrations and external forcing fixed. Water-vapour, lapse-rate, cloud and sea-ice feedbacks respond; carbon-cycle and ice-sheet feedbacks are excluded. This is actual equilibrium sensitivity, not transient warming, a model ensemble mean or an effective sensitivity inferred by assuming today's feedback pattern never changes.

Each round reads the evidence that was public at a stated cutoff. Later evidence goes into a later round; the market itself has no expiry date.

Resolution criteria

YES: Two independent multi-line assessments combining instrumental energy balance, paleoclimate and process constraints place the 95% interval for this exact quantity wholly above 3 kelvin, explicitly accounting for state/pattern dependence and dependence among evidence lines. NO: The same eligible assessments place the 95% upper bound <= 3 kelvin. A best estimate on one side, an uncertainty interval crossing 3, seasonal or volcanic feedback alone, or one model simulation is UNDECIDED. The boundary is a convention, not a scientifically established danger threshold. Reference sources: IPCC AR6 WGI chapter 7 (https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-7/). Evidence policy: use public primary research with methods and uncertainty, plus the named reference sources below. A preprint can inform the estimate but cannot alone meet a terminal criterion; require a peer-reviewed primary result and an independent reproduction using non-overlapping observations or independently prepared samples, unless this is a mathematical proof or the specific criterion instead requires independently implemented calculations. Report data provenance, exclusions, calibration, statistical model and systematic uncertainty. Independence means different data acquisition, not two papers reanalysing the same sample. For a quantitative terminal test, both independent results must meet the stated threshold; disagreement or an interval crossing the boundary means UNDECIDED. Use the final corrected version public at the signed round's evidence cutoff (UTC); exclude later evidence until a later eligible round. Every report in a terminal round must use the same cutoff, covered by the verified signed context and enforced by the configured terminal protocol; a different cutoff requires a new eligible round, never reinterpretation of a signed report or mutation of an immutable binding. This market has no calendar expiry. Retracted findings cannot supply a terminal result. If a named source disappears, use its DOI/publisher or an archived identical version, then an equivalent primary publication applying these unchanged definitions; if none is accessible, remain UNDECIDED, never substitute a different test. Missing data, failed replication, a null search outside the specified domain, or an untested alternative is not automatically NO. These are instructions for evidence assessment, not an automatic truth oracle: scientific interpretation and systematic-error judgment remain. Settlement follows the configured platform mode: terminal mode requires one valid round with all three frozen models returning the same explicit YES or NO and criterion_met=true; any UNDECIDED, failure or disagreement leaves it unresolved. Legacy proposal/challenge mode requires its recorded review process. Model agreement does not prove scientific truth. Invalidity is not NO and this text does not authorize a refund or cancellation: only a cancellation rule disclosed before exposure, if the configured contract supports it, can apply. Otherwise pause new entries and preserve holders' existing rights. Never reinterpret terms after listing.

The definition does not change when an AI estimate changes. Read the listing policy and this market's settlement status.