Claim

Model ledger-default@0.1.0 ledger-strict@0.1.0 ledger-default@0.2.0 ledger-strict@0.2.0 ledger-default@0.3.0 (default) ledger-strict@0.3.0 Snapshot seq

Topics

Climate · 1efd24fe Earth science · 1efd24fe

Assessment

Why?

Strongest counted support: The study reports reduced tropical Atlantic nitrogen fixation in the warm late Pliocene, later increasing and varying with an approximately 41,000-year cycle in the Caribbean. weight 2.000000 evidence

Suppressed as dependent: The quoted passage directly supports the warm-Pliocene reduction, cooler-Pleistocene increase, and approximately 41,000-year Caribbean cycle.

Review gaps: qualifiers reviewed, opposing search done, independence reviewed

What would most change this: One independent, direct measurement that contradicts this claim would move it from Supported to Leans supported.

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Checked as part of

Statements this claim was broken out of. The claim is scored on its own; a statement's reading only counts its claims.

• “Nitrogen-isotope measurements from tropical Atlantic sediment-core foraminifera indicate that natural nitrogen fixation was substantially lower during the...” · 1 claim · 29 September 2026
• “Nitrogen-isotope measurements from tropical Atlantic sediment-core foraminifera indicate that natural nitrogen fixation was substantially lower during the...” · 1 claim · 29 September 2026

Evidence for

• The study reports reduced tropical Atlantic nitrogen fixation in the warm late Pliocene, later increasing and varying with an approximately 41,000-year cycle in the Caribbean.

  From Reduced N2 fixation in the tropical Atlantic Ocean during the warm late Pliocene Read 2026-09-29 Relevance DIRECT Steps 0 Counted

• Independent coverage reports reduced tropical Atlantic nitrogen fixation during the warm late Pliocene and recovery in the cooler Pleistocene.

  From Fossil plankton shells reveal reduced nitrogen fixation in warmer oceans 3 million years ago Read 2026-09-29 Relevance STRONG Steps 0 Counted

  Secondary science coverage corroborates the main temporal direction; the primary paper supplies the detailed isotope and cycle analysis.

• The quoted passage directly supports the warm-Pliocene reduction, cooler-Pleistocene increase, and approximately 41,000-year Caribbean cycle.

  From Reduced N2 fixation in the tropical Atlantic Ocean during the warm late Pliocene Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Evidence against

None.

Qualifications

• The evidence comes from two named Atlantic core sites and covers approximately 3.6 to 2 million years ago, not all tropical Atlantic sediments.

  From Reduced N2 fixation in the tropical Atlantic Ocean during the warm late Pliocene Read 2026-09-29 Relevance DIRECT Steps 0 Counted

Suppressed as dependent

Evidence	Group	Kept instead
eed6ac41		9c9b0b02

Inferences

Concluded from

None.

Used as a premise in

None.

An inference is interpretation, not evidence: it never changes the assessment of its conclusion. Each premise is a claim with its own evidence.

Threads

None. Threads are for disagreements about how a determination was made — a statement whose figures are not in the passage it rests on, two sources that may share an origin. Something about the world belongs in the evidence above.

Claim edges

None. Edges are stored and displayed; v0.1 does not propagate probability across them.

Review checklist

Review checks: 1 of 4

2 checks by this claim's own author, alongside the independent review above. 1 QUALIFIER CHECK · 1 EVIDENCE VERIFICATION. A check by the person who recorded a claim does not raise its review coverage.

Check	Done	By
qualifiers reviewed	no
opposing search done	no
independence reviewed	no
primary source reviewed	yes	87354e76, 9c9b0b02, 6be5ac6a

Summary

Contribution history

seq	event	detail
16801	APPENDED
16802	ACCEPT	AUTOMATIC_AFTER_VALIDATION
16807	LINK_EVIDENCE	by 1efd24fe (accepted)
16816	LINK_EVIDENCE	by 1efd24fe (accepted)
16818	TASK_RESULT	by 1efd24fe (accepted)
25787	TASK_RESULT	by 1efd24fe (accepted)

Score trace

{
  "claim": "60ca89ca-674f-89fa-8632-0003d21091c0",
  "links": [
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      "direction": "SUPPORT",
      "magnitude": "1.080000",
      "relevance": "STRONG",
      "extraction": "UNVERIFIED",
      "provenance": "INDEPENDENT",
      "observation": "DIRECT_TEXT",
      "source_type": "SECONDARY_TEXT",
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      "effective_weight": "1.080000",
      "interpretive_steps": 0
    },
    {
      "link": "835d0d41-3d4e-88cf-b675-37ab87354e76",
      "group": null,
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      "group": null,
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      "link": "fe6241ce-e35e-8bb9-b298-fbf86be5ac6a",
      "group": null,
      "reason": "dependent_strongest_only",
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    }
  ],
  "model": "ledger-default@0.3.0",
  "prior": "0.50",
  "variants": {
    "spread": "0.0859",
    "permissive": "0.9821",
    "conservative": "0.8962"
  },
  "code_hash": "sha256:c61a6fdf35a754a0d7e958df149036a083c0eaeb7d2d2e52704ec32b0c36def7",
  "contested": false,
  "stability": "HIGH",
  "claim_type": "HISTORICAL",
  "config_hash": "sha256:86768038080b8ab5233f1e4b7aba10af05b5bb44caa432095150b90e81209809",
  "probability": "0.9561",
  "provisional": true,
  "evidence_sum": "3.080000",
  "snapshot_seq": 25788,
  "prior_log_odds": "0.000000",
  "support_groups": 2,
  "model_dependent": false,
  "review_coverage": "0.25",
  "truth_evaluable": true,
  "assessment_state": "SUPPORTED",
  "review_checklist": {
    "qualifiers_reviewed": {
      "by": [],
      "ok": false
    },
    "opposing_search_done": {
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    },
    "independence_reviewed": {
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    },
    "primary_source_reviewed": {
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      ],
      "ok": true
    }
  },
  "contradict_groups": 0,
  "rounding_boundary": false,
  "posterior_log_odds": "3.080000",
  "not_applicable_reason": null,
  "independence_unreviewed": 4
}