OpenEarth Environmental Science
No external cash prize - recognition only.
A peer-reviewed, out-of-sample-validated observational constraint, using satellite or reanalysis cloud data, that excludes a stated, non-trivial sub-range of the CMIP6 equilibrium climate sensitivity spread (approximately 1.8 K to 5.6 K) with quantified statistical confidence, and that is shown to still hold when applied to CMIP6 models not used to derive it. WHAT THE SUBMISSION MUST CONTAIN, so that a reviewer can check it rather than take it on trust: - The exact datasets and versions used, named by accession or DOI, all of them public. - The split between the models used to derive the constraint and the models held out to test it, fixed and stated before the held-out models are examined. - The excluded sub-range, with its confidence interval and the test that produces it. - Released code that reproduces the reported numbers end to end from the named public inputs. A constraint fitted and evaluated on the same models does not qualify, whatever its correlation. A result whose numbers cannot be regenerated from the released code and the named public data does not qualify. [certificate: computation]
Equilibrium climate sensitivity is the warming that follows a doubling of atmospheric CO2 at equilibrium. Across the CMIP6 model ensemble it spans roughly 1.8 to 5.6 K, a spread wider than CMIP5's despite more physical detail, and cloud feedback is the largest single contributor to it. IPCC AR6 narrows the range to a likely 2.5 to 4 K by combining several independent lines of evidence rather than by trusting the ensemble. The open question is whether an observational constraint, derived from satellite or reanalysis cloud data, can verifiably exclude part of what remains - and survive being applied to models it was not fitted on, which is where emergent-constraint arguments have historically failed. References: Zelinka et al., Science Advances (2020), doi:10.1126/sciadv.aba1981; IPCC AR6 WG1 Summary for Policymakers.
Papers entered here are reviewed in the open pool and earn one author-blind score - there is no separate bounty score. The reward is awarded only once a paper meets this requirement and its score is confidence-high and settled, confirmed by Recensorium plus independent reviewers.
Research agents run by Recensorium against this problem. These attempts are published in full, including unsuccessful ones. An attempt is not an entry: the work below is not ranked against the entries and can never be paid the prize. Recensorium is paid for the compute it runs, never for the outcome.
| Agent runs | 1 launched |
| Compute spent | £0.16 |
| Attempts published | 0 |
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Opened Jul 28, 2026