Methodology
How the edition was made: methods, the model card, the evidence cut and its age, the acceptance record and the glossary.
Contents
- ·Edition home
- ·Executive summary
- 1Pressure builds across the system
- 2Key findings
- 3Systems and sectors at baseline
- 4Risks and capability
- 5Ocean heat and reef loss that overlaps stress on the Atlantic circulation and the Amazon
- 6Readings from the other desks
- 7The 2027 agenda
- 8Systems in depth
- AMethodology
- A.1 Methods
- A.2 Model card, Planetary Boundaries Model v0
- A.3 The baseline evidence cut
- A.4 Evidence age and coverage
- A.5 Evidence cards, two anchor sources
- A.6 Publication acceptance record
- A.7 Status words
- A.8 How the edition is made, released and corrected
- A.9 Glossary and abbreviations
- A.10 Technical annex
- BData appendix
- CReferences and record
- ·Complete edition, for print
A.1Methods
The global baseline uses published values and four simple derivations. Each is shown in full so that any reader can reproduce it.
| No. | Derivation | Calculation | Result |
|---|---|---|---|
| (1) | CO2 rise from 2024 to 2025 | 425.62 minus 422.79 | ≈ 2.83 ppm |
| (2) | CO2 above the climate boundary value, 2025 | 425.62 minus 350 | ≈ 76 ppm |
| (3) | Nitrogen flow relative to its limit | 165 ÷ 62 | ≈ 2.7 times |
| (4) | Margin of ocean aragonite saturation to its limit | 2.86 minus 2.84 | ≈ 0.02 |
| Strength | Definition |
|---|---|
| STRONG | a disruption in the source system has historically changed the target system’s service or output within one season, in more than one region |
| MODERATE | an effect is documented but buffered or slower |
| WEAK | an effect is plausible but not documented at global scale |
| Label | Rule |
|---|---|
| Reported | value as issued by its source, with year |
| Inferred | reasoned from cited evidence; never a measurement |
| Estimated | Nexus analytical value with stated method |
| Scenario | conditional on stated assumptions |
| Expert input | structured editorial judgement awaiting evidence |
A.2Model card, Planetary Boundaries Model v0
- Model ID
- MDL-SR09-PLANETARY · v0.1
- Purpose
- represent the Earth system as nine linked boundary processes and the mechanisms by which pressure spreads between climate, ocean, land, water and the living biosphere
- Family
- graph-based system of systems
- Inputs
- the cited sources of this edition; no proprietary data
- Method
- expert-specified coupling strengths (STRONG · MODERATE · WEAK) from assessments and analogue events
- Validation
- none yet, first validation against federation evidence in 2027
- Uncertainty
- qualitative; strengths are hypotheses, not measurements
- Domain of validity
- global scale; not for asset-, site- or country-level use
- Reproducibility
- strength table and sources published in this edition
20couplings
typed in v0
8strong
documented within one season
6moderate
documented, buffered
6weak
plausible, undocumented
A.3The baseline evidence cut
Every Nexus edition is published from a frozen evidence cut. The global baseline cut is documentary: it pins the exact edition of every source cited. Federation cuts begin with the first national Foundry cuts in 2027.
- Cut ID
- DC-STRATEGIC-PLANETARY-GLOBAL-2026-B0
- Type
- baseline documentary cut
- Resolution policy
- pinned · as of 30 September 2026
- Sources pinned
- 45 cited sources, each at the edition and access date in the references
- Model runs
- none at baseline, analytical values are stated with their method
- Digest
- computed at freeze and recorded in the publication record
- Supersedes
- nothing, first cut of the series
- Superseded by
- the 2027 planetary boundaries annual cut
Lineage
- 01
source edition
- 02
pinned citation
- 03
finding
- 04
page
- 05
publication record
| Element | Baseline 2026 | 2027 global annual |
|---|---|---|
| Sources | cited global publications, pinned by edition | national, regional and sector cuts through one graph |
| Analysis | stated methods and editorial estimates | typed analysis specifications |
| Models | Planetary Boundaries Model v0 specification | model runs with receipts |
| Findings | twelve baseline findings | findings re-bound to federation evidence |
| Review | five passes scheduled | five passes on the exact digest |
A.4Evidence age and coverage
A 2026 global edition rests on evidence observed in many different years. This page shows each time base, so that no single year label hides older evidence.
| Indicator | Observed | Released | Cadence | Next release |
|---|---|---|---|---|
| Planetary boundary status | 2025 | 2025 | annual | next Planetary Health Check |
| Temperature of 2025 | 2025 | Jan 2026 | annual | early 2027 |
| Atmospheric CO2 | 2025 | 2025 to 2026 | annual | early 2027 |
| Warming update to COP30 | Jan to Aug 2025 | Nov 2025 | annual | next WMO update |
| Emissions outlook | 2025 | Nov 2025 | annual | next report |
| Tipping thresholds | 2022 | Sep 2022 | one-off | no update found |
| Tipping report | 2025 | Oct 2025 | periodic | next report |
| Atlantic circulation studies | 2023 to 2025 | 2023 to 2025 | ad hoc | further studies |
| Amazon transitions | to 2050 (projection) | 2024 | one-off | no update found |
| Biodiversity assessment | 2019 | May 2019 | periodic | next IPBES assessment |
| System | Coverage | Thinnest dimension |
|---|---|---|
| Climate | GOOD | dataset agreement |
| Ocean | PARTIAL | circulation record |
| Land and forests | PARTIAL | thresholds |
| Fresh water | PARTIAL | paper-level values |
| Nutrients | PARTIAL | regional values |
| Chemicals and plastics | THIN | control variable |
| Biosphere | PARTIAL | rates of change |
| Ozone and aerosols | PARTIAL | regional detail |
| Field | Source that would fill it | Blocker |
|---|---|---|
| Boundary control-variable values read from the primary report | Planetary Health Check 20252 | values come from a public dashboard page; the report itself was not opened and its page shows no explicit date |
| Interaction strengths between boundaries | Earth-system modelling studies135 | no consolidated quantification found |
| Observed strength of the Atlantic overturning circulation over a long record | ocean observing programmes1617 | direct records are short and studies disagree |
| Regional thresholds for Amazon and ice-sheet tipping | Global Tipping Points Report full text737 | only a press release was opened for the report; the journal article is paywalled |
| IPCC Sixth Assessment figures from the report text | IPCC Synthesis Report30 | the report page returned an access error; no figure is used |
| Green water boundary values from the paper | Wang-Erlandsson et al.23 | only the record was read, with no abstract; values come from the dashboard |
| Control variable for novel entities | Persson et al.22 | the authors name data gaps and propose several candidates; none is agreed |
| Global Carbon Budget 2025 headline numbers | Global Carbon Budget 202512 | the page gave only a 1.1% projected rise in fossil emissions |
| Cost of tipping-point impacts on one basis | integrated assessment studies | no consolidated series retrieved |
| National and company downscaling of boundaries | national environment ministries and target-setting bodies42 | not reviewed |
| Capability rungs beyond monitoring and policy | ministries, agencies, observing programmes | not reviewed |
| Agreement between warming datasets on one baseline | Copernicus, WMO and the indicators study8913 | datasets use different methods and periods; not reconciled here |
A.5Evidence cards, two anchor sources
Issued by Planetary Boundaries Science with a named author team. Annual. Role: binds SYS-001. Coverage: global, nine boundaries. The publication page and a status dashboard were read; the report was not opened.
EVD-SR09-001
Planetary Health Check 2025 publication page2
Issued by the University of Exeter with partners. Periodic. Role: binds CLI-005. Coverage: global tipping elements. A release page was read; the full report was not opened.
EVD-SR09-002
Global Tipping Points Report 2025, release page7
| Dimension | EVD-SR09-001 | EVD-SR09-002 |
|---|---|---|
| Completeness | nine boundaries, one or two variables each | selected tipping elements |
| Timeliness | annual | about days after a stated cut-off |
| Revision | count changed from six to seven in two years | new assessment each few years |
| Method transparency | control variables listed | expert synthesis with ranges |
| External validation | published method papers | expert authors from many institutions |
Evidence cards to follow in 2027
A.6Publication acceptance record
Editorial self-check at evidence close. Every applicable item carries a disposition; the remaining items are review, approval and deposit.
| Group | Area | Items | Pass | N/A | Pending |
|---|---|---|---|---|---|
| D1 | Identity and scope | 8 | 8 | 0 | 0 |
| D2 | Source and data | 12 | 9 | 1 | 2 |
| D3 | Analysis and models | 12 | 3 | 8 | 1 |
| D4 | Findings and claims | 9 | 8 | 0 | 1 |
| D5 | Figures, tables, maps | 10 | 6 | 2 | 2 |
| D6 | Editorial and citations | 10 | 8 | 0 | 2 |
| D7 | Review and approval | 13 | 0 | 0 | 13 |
| D8 | Artefact and design | 12 | 7 | 0 | 5 |
| D9 | Registry and release | 9 | 0 | 0 | 9 |
Publication gate
- Conditions met
- 14 of 23 at evidence close
- Blocking problems
- none recorded
- Open conditions
- reviews, approval of the exact digest, deposit, registry pointer
Not applicable at baseline
- Model runs
- first runs in Q1 2027
- Maps
- plates in Q2 2027
- Waivers
- none
A.7Status words
| Status | What it means |
|---|---|
| Observed | Measured directly and published by the source. |
| Reported | Published statistics of an official or institutional source. |
| Declared | Stated by the body concerned; not independently measured. |
| Estimated | A Nexus estimate from cited evidence, with its method in Annex A. |
| Modelled | Produced by a stated model from cited inputs. |
| Inferred | Reasoned from cited evidence; not measured. |
| Forecast | A projection by the cited source. |
| Simulated | A simulation result under stated assumptions. |
| Scenario | A conditional statement under stated assumptions; never a prediction. |
| Expert input | Expert judgement, recorded with its basis. |
| Candidate | Proposed for a later edition; not yet evidence. |
| Evidence-quality levels (EQL 1 to 5) grade the source behind a value; they are not a score of the subject. | |
A.8How the edition is made, released and corrected
Every edition is built from a sealed evidence cut, reviewed under three keys, signed and deposited before any site shows it as published; corrections go to Nexus Standards as change proposals and feed the next cut.
| Step | What happens | Source |
|---|---|---|
| 01 Evidence arrives from the pillars | Foundry seals observations and indicator series, Universe hands over after-action and scenario findings, and contributions are screened at every gateway, including this site’s. | |
| 02 The cut is sealed | On the cut date the evidence is pinned under one identifier, so anyone can rebuild the edition from exactly what it was built on. | |
| 03 The edition is assembled | The edition is drafted from its template and content pack. Agents may draft; they never publish and never decide. | |
| 04 The keys turn | At the publisher of record the truth key comes first: every value is checked against its source or stated method before the meaning and capital keys turn. No edition moves on until every key has been turned by a named steward. | |
| 05 The gate opens | A named approver releases one exact digest of the edition; any change after this point is a new version, never a silent edit. | |
| 06 Signed and deposited | The PDF, the web edition and the data bundle are signed together with a manifest and an RO-Crate description, and deposited on Zenodo with a concept and a version DOI. | |
| 07 Published on its desk’s site | Only then does the edition show as published on its desk’s Reports site, and the Collection lists it as a part. | |
| 08 Corrections go to Standards | Method and correction findings go to Nexus Standards as change proposals; citations, corrections and new contributions feed the next evidence cut. |
A teaching model of the process, not a forecast and not a record of any run; dates and counts on this page come from the programme record. Sources: Reports governance at GCRI Canada (2026); Zenodo, repository of record for Reports deposits (2026).
Lifecycle, one state at a time: Draft, Computed, Evidence bound, Reviewed, Approved for release, Published, Corrected, Superseded. This edition is a draft.
A.9Glossary and abbreviations
| Term | Meaning |
|---|---|
| Baseline Edition | the inaugural annual edition that fixes the reference state for the series |
| WEFH+B | water, energy, food, health and biodiversity, the national nexus core |
| Coupling | a typed dependency through which one system transmits to another |
| Protection gap | the share of losses not covered by insurance |
| Capability ladder | LISTED → EXISTS → ADEQUATE → TESTED → DEMONSTRATED |
| EQL | evidence-quality level, 1–5 |
| Evidence cut | a frozen resolution of exact sources and versions |
| NNC · NLC · NWG | National Nexus Consortium · National Leadership Council · National Working Groups |
| Abbreviation | Expansion |
|---|---|
| AMOC | Atlantic Meridional Overturning Circulation |
| CO2 | carbon dioxide |
| CTP | climate tipping point |
| ECMWF | European Centre for Medium-Range Weather Forecasts |
| GMST | global mean surface temperature |
| IPBES | Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services |
| IPCC | Intergovernmental Panel on Climate Change |
| NDC | nationally determined contribution |
| NOAA | US National Oceanic and Atmospheric Administration |
| ppm | parts per million |
| UNEP | United Nations Environment Programme |
| WMO | World Meteorological Organization |
A.10Technical annex
| Item | Annex | Contents | Status |
|---|---|---|---|
| A.1 | Indicator definitions | the global indicator set, with units and sources | IN THIS EDITION |
| A.2 | Coupling strengths | the twenty-cell matrix and its rationale | IN THIS EDITION |
| A.3 | Scenario specification | SCN-SR09-CMP-01 assumptions and signposts | IN THIS EDITION |
| A.4 | Capability placements | rung evidence for fifteen functions | IN THIS EDITION |
| A.5 | Model diagnostics | first runs and validation | 2027 |
| A.6 | Sensitivity analyses | influence of coupling strengths | 2027 |
| A.7 | Regional notes | regional Earth-system cards | WITH REGIONAL EDITIONS |
| A.8 | Review statements | pass-by-pass review record | AT RELEASE |
A.1 · indicator definition: boundary transgression
- Construct
- a control variable that has passed the limit set for its planetary boundary
- Unit
- the unit of each control variable, for example ppm or Tg a year
- Method
- comparison of the current value with the limit in the framework
- Source
- Planetary Health Check 20252 and boundary status dashboard3
- Uncertainty
- limits carry ranges, and some margins are very small
- Known limits
- a crossed boundary is not a tipping point; it marks rising risk
Notes
Numbers are the edition’s reference numbers, so a note reads the same in every chapter. The full list, with every source and its licence, is in Annex C. Annex C, references
- 2Sakschewski, B., Caesar, L., Rockström, J. et al., Planetary Health Check 2025: A Scientific Assessment of the State of the Planet (publication page; seven of nine boundaries breached). Planetary Boundaries Science, Potsdam. Observation year 2025. Accessed 2026-11-03.back
- 1Richardson, K., Steffen, W., Lucht, W., Bendtsen, J., Cornell, S.E., Rockström, J. et al., Earth beyond six of nine planetary boundaries, Science Advances 9(37), eadh2458, 2023 (six of nine boundaries transgressed; ocean acidification near its boundary). Observation year 2023. Accessed 2026-11-03.back
- 35UNVERIFIED, not opened: Rocha, J.C., Peterson, G., Bodin, O. and Levin, S., Cascading regime shifts within and across scales, Science 362, 1379 to 1383, 2018, cited from memory. Observation year 2018. Accessed 2026-11-03.back
- 16Baker, J. et al., Continued Atlantic overturning circulation even under climate extremes, Nature 638, 987 to 994, 2025 (34 models; collapse this century judged unlikely; weakening still expected; abstract and Met Office release read). Observation year 2025. Accessed 2026-11-03.back
- 17van Westen, R.M., Kliphuis, M. and Dijkstra, H.A., Physics-based early warning signal shows that AMOC is on tipping course, Science Advances 10, eadk1189, 2024 (full text read). Observation year 2024. Accessed 2026-11-03.back
- 7Lenton, T.M. et al. (eds.), Global Tipping Points Report 2025 (release page read, not the full report; 10 October 2025; coral reef threshold central estimate 1.2 degrees C, range 1 to 1.5). University of Exeter, Exeter. Observation year 2025. Accessed 2026-11-03.back
- 37UNVERIFIED, not opened: Boulton, C.A., Lenton, T.M. and Boers, N., Pronounced loss of Amazon rainforest resilience since the early 2000s, Nature Climate Change 12, 271 to 278, 2022, cited from memory. Observation year 2022. Accessed 2026-11-03.back
- 30UNVERIFIED, not opened: IPCC (ed.), Climate Change 2023: Synthesis Report of the Sixth Assessment Report, cited from memory; the page returned an access error; no figure used. Intergovernmental Panel on Climate Change, Geneva. Observation year 2023. Accessed 2026-11-03.back
- 23Wang-Erlandsson, L. et al., A planetary boundary for green water, Nature Reviews Earth and Environment 3(6), 380 to 392, 2022 (bibliographic record read, no abstract; no figure taken from it). Observation year 2022. Accessed 2026-11-03.back
- 22Outside the Safe Operating Space of the Planetary Boundary for Novel Entities, Environmental Science and Technology 56(3), 1510 to 1521, 2022 (abstract read). Observation year 2022. Accessed 2026-11-03.back
- 12Global Carbon Project (ed.), Global Carbon Budget 2025 (landing page: projected 1.1% rise in fossil CO2 emissions, a record high; headline tables not read). Observation year 2025. Accessed 2026-11-03.back
- 42UNVERIFIED, not opened: Science Based Targets Network, Science-Based Targets for Nature: Initial Guidance for Business, 2020, cited from memory. Observation year 2020. Accessed 2026-11-03.back
- 8ECMWF and Copernicus Climate Change Service (eds.), Global Climate Highlights 2025 (news release: 1.47 degrees C above 1850 to 1900; third warmest year; 2023 to 2025 average above 1.5). ECMWF, Reading. Observation year 2025. Accessed 2026-11-03.back
- 9WMO (ed.), State of the Climate 2025 Update for COP30 (January to August 2025 at 1.42 degrees C; CO2 423.9 ppm in 2024; sea-level rise 4.1 mm a year, 2016 to 2025). World Meteorological Organization, Geneva. Observation year 2025. Accessed 2026-11-03.back
- 13Indicators of Global Climate Change 2024, Earth System Science Data 17, 2641, 2025 (2015 to 2024 average 1.24 degrees C; 2024 at 1.52; human-induced 1.36; energy imbalance 0.89 W per m² for 2005 to 2024). Observation year 2024. Accessed 2026-11-03.back
- 10NOAA Global Monitoring Laboratory (ed.), Global annual mean CO2 growth data (annual means 2020 to 2025; 425.62 ppm in 2025). NOAA, Boulder. Observation year 2025. Accessed 2026-11-03.back
- 3Globaia (ed.), Planetary boundaries status dashboard (nine boundaries with control-variable values and limits; page last updated 15 June 2026; its summary text still says six while its table shows seven). Observation year 2025. Accessed 2026-11-03.back