Methodology

How the edition was made: methods, the model card, the evidence cut and its age, the acceptance record and the glossary.

14 min read0 figures13 tables18 notesNR-SECTOR-CITIES-GLOBAL-2026-BASELINE

Contents

A.1Methods

The global baseline uses published values and four simple derivations. Each is shown in full so that any reader can reproduce it.

Table A.1Methods
No.	Derivation	Calculation	Result
(1)	Urban share, national definitions, 2025	4,750,578,960 ÷ 8,215,424,893	57.8%
(2)	Urban relative to rural PM2.5, population-weighted, 2023	27.30 ÷ 15.74	≈1.7 times
(3)	Slum population cross-check, 2022	24.80% × 4.559 billion urban people	≈1.13 billion, against 1.12 billion published
(4)	Increase in urban population, 2020 to 2025	4,750,578,960 − 4,433,048,326	≈318 million

Table A.2Coupling strength scale (matrix and model card)
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

Table A.3Status grammar
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, Cities Sector Model v0

Model ID: MDL-GS10-CITIES · v0.1
Purpose: represent the global urban system and its couplings to water, energy, food, health and nature
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

4strong

documented within one season

8moderate

documented, buffered

8weak

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-SECTOR-CITIES-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 cities annual cut

Lineage

01
source edition
02
pinned citation
03
finding
04
page
05
publication record

Table A.4From the baseline cut to the federation cut
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	Cities Sector 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.

Table A.5Evidence age and coverage
Indicator	Observed	Released	Cadence	Next release
Urban population and cities	2025	Nov 2025	biennial	next World Urbanization Prospects
Urban shares and access series	2024 to 2025	Oct 2026	annual	next World Bank update
Slums and Goal 11 indicators	2022 to 2024	2026 release	annual	next SDG database release
Urban emissions and risk assessments	2020	2022	cycle	IPCC special report on cities
Heat exposure	1983 to 2016	2021	one-off	update not scheduled
Flood exposure	2020 grid	2022	one-off	update not scheduled
Subnational finance	2020	Oct 2022	triennial	next observatory edition
Heat deaths	2000 to 2019	as updated	as updated	WHO updates
Air pollution deaths	2019	as updated	as updated	WHO updates
Green space	2022	2023	annual	Lancet Countdown

Table A.6Coverage by system at baseline
System	Coverage	Thinnest dimension
Settlement	GOOD	town and rural shares on one basis
Housing	PARTIAL	inadequate housing on one basis
Services	PARTIAL	service quality in informal settlements
Heat	PARTIAL	urban heat deaths
Flood	PARTIAL	city-level loss series
Finance	PARTIAL	city-level revenue and debt
Buildings	THIN	primary report not opened
Resilience	THIN	tested capabilities in cities

Table A.7Designed empty states: what is not bound, what would fill it and why
Field	Source that would fill it	Blocker
Share of population in towns and in rural areas on the Degree of Urbanisation basis	UN DESA World Urbanization Prospects 2025 tables¹	the summary report was not opened; the release page states only the 45% city share
Buildings share of global energy use and emissions, from the primary report	UNEP Global Status Report for Buildings and Construction 2024 to 2025²⁷	the report page returned an access error; figures seen only in search summaries are not used
Municipal solid waste generation, cost and uncontrolled disposal worldwide	UNEP Global Waste Management Outlook 2024²⁸	the report page returned an access error; only the regional collection coverage in the SDG Report is used⁴
Urban heat deaths, split from the national total	WHO and national health agencies; Lancet Countdown⁴³	the WHO page gives total deaths and regional shares only; the Lancet 2025 report was not opened
People at risk who lack access to cooling	IEA Future of Cooling³³	not opened; no figure is used
Urban food insecurity, split from the national total	FAO State of Food Security and Nutrition²⁴	the 2026 page gives global figures only; the edition on the rural-urban continuum was not opened
Inadequate housing worldwide, on one basis	UN-Habitat; SDG indicator 11.1.1 inadequate housing series³	the database returned no world value for the inadequate-housing series at access
Urban air pollution deaths by city	WHO ambient air quality database⁸⁴⁴	the database was not opened; no city figure is used
City adaptation plans that are funded and in force	city reporting platforms; IPCC⁷	the IPCC states that few plans are implemented; no global count was found
Urban infrastructure investment needs, on one basis	World Bank; OECD	the figure found covers all resilient low-carbon infrastructure in low- and middle-income countries, not cities alone¹¹
Disaster losses in cities	UNDRR Global Assessment Report 2025³¹	the report page returned an access error
City-level revenue, debt and transfers worldwide	OECD and UCLG observatory²²	the observatory reports subnational governments as a whole, not cities
Public transport access after 2020	SDG database indicator 11.2.1³	the database holds a 2020 value only at access
Cyber incidents against municipal services	national authorities and operators	incident data are not published on a common basis
Capability rungs beyond those cited	municipalities, regulators, ministries	not reviewed

A.5Evidence cards, two anchor sources

Issued by the UN Population Division (November 2025) from national data and a harmonised grid-based Degree of Urbanisation. Biennial. Role: binds SYS-001 and SYS-002 and the settlement tiles.

EVD-GS10-001

UN DESA World Urbanization Prospects 2025¹

Assessment of urban emissions (2022), consumption-based. Cycle. Role: binds CLI-005 and the emissions scenario figure. Estimates include electricity and goods consumed in cities.

EVD-GS10-002

IPCC AR6 Working Group III chapter 8⁶

Table A.8Quality dimensions at baseline
Dimension	EVD-GS10-001	EVD-GS10-002
Completeness	more than 12,000 cities and three settlement classes; towns and rural shares not read here	urban emissions for 2015 and 2020; aviation, marine fuels and land-use change excluded
Timeliness	about 1 year after the base year	about 2 years after the base year
Revision	new edition adopts a new method; not comparable with earlier editions without the bridge	assessment cycle; next cities special report in preparation
Method transparency	method note in the release	chapter methods and footnotes published
External validation	compared with national statistics	expert review

Evidence cards to follow in 2027

UN DESA¹: country and city tables for towns and rural areas
UNEP²⁷: buildings energy and emissions shares from the report
UN Statistics Division³: inadequate housing series and later transport values
WHO¹⁰: city-level heat deaths where published

A.6Publication acceptance record

Editorial self-check at evidence close. Every applicable item carries a disposition; the remaining items are review, approval and deposit.

Table A.9Publication acceptance record
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

Table A.10The status every value carries
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

Table A.11Series terms
Term	Meaning
Baseline Edition	the inaugural annual edition that fixes the reference state for the series
WEFH+B	cities, 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

Table A.12Abbreviations used in this edition
Abbreviation	Expansion
DEGURBA	Degree of Urbanisation
GHG	greenhouse gas
GtCO2-eq	gigatonnes of carbon dioxide equivalent
HDI	Human Development Index
IPCC	Intergovernmental Panel on Climate Change
LMIC	low- and middle-income countries
PM2.5	fine particulate matter of 2.5 micrometres or less
SDG	Sustainable Development Goal
SNG-WOFI	World Observatory on Subnational Government Finance and Investment
SSP	Shared Socioeconomic Pathway
UCLG	United Cities and Local Governments
UN DESA	United Nations Department of Economic and Social Affairs

A.10Technical annex

Table A.13Technical 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-GS10-HTF-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	City-region notes	cards for the major delta, coastal and metropolitan regions	WITH REGIONAL EDITIONS
A.8	Review statements	pass-by-pass review record	AT RELEASE

A.1 · indicator definition: proportion of urban population living in slums

Construct: share of the urban population living in households with one or more housing deprivations
Unit: share of urban population
Method: custodian indicator from household surveys and censuses, with modelled estimates
Source: SDG database and Goal 11 page³⁵
Uncertainty: the World Bank series differs by 1.6 percentage points for 2022²
Known limits: a proxy; does not capture tenure security, eviction risk or neighbourhood quality

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

1UN DESA Population Division (ed.), World Urbanization Prospects 2025: Summary of Results (publication page and press release; 45% of 8.2 billion people in cities, 33 megacities, more than 12,000 cities, Degree of Urbanisation). United Nations, New York, November 2025. Observation year 2025. Accessed 2026-11-03.back
27UNVERIFIED, not opened: UNEP and GlobalABC (eds.), Global Status Report for Buildings and Construction 2024 to 2025; the report page returned an access error and the figures seen only in search summaries (buildings about 32% of energy and 34% of CO2) are not used. United Nations Environment Programme, Nairobi, 2025. Observation year 2023. Accessed 2026-11-03.back
28UNVERIFIED, not opened: UNEP (ed.), Global Waste Management Outlook 2024; the report page returned an access error and the figures seen only in search summaries are not used. United Nations Environment Programme, Nairobi, 2024. Observation year 2023. Accessed 2026-11-03.back
4United Nations (ed.), The Sustainable Development Goals Report 2025, Goal 11 (housing, flood, local risk reduction strategies, waste collection, national urban policies). United Nations, New York. Observation year 2024 (indicator data 2010 to 2024). Accessed 2026-11-03.back
43UNVERIFIED, not opened: Romanello, M. et al., The 2025 report of the Lancet Countdown on health and climate change; the journal page returned an access error and no figure is used. Elsevier, London, 2025. Observation year 2024. Accessed 2026-11-03.back
33UNVERIFIED, not opened: IEA (ed.), The Future of Cooling: Opportunities for energy-efficient air conditioning, cited from memory without figures. International Energy Agency, Paris, 2018. Observation year 2018. Accessed 2026-11-03.back
24FAO, IFAD, UNICEF, WFP and WHO (eds.), The State of Food Security and Nutrition in the World 2026 (publication page; 645 million people faced hunger in 2025; about 2.7 billion cannot afford a healthy diet). Food and Agriculture Organization, Rome. Observation year 2025. Accessed 2026-11-03.back
3UN Statistics Division (ed.), Global SDG Indicators Database, API extract of series EN_LND_SLUM, EN_ATM_PM25, EN_ACS_URB_OPENSP, SP_TRN_PUBL, EN_REF_WASCOL and SD_CPA_UPRDP (release 2026.Q3.G.01). United Nations, New York. Observation year 2024 (slums), 2023 (PM2.5) and 2020 (transport, open space). Accessed 2026-11-03.back
8WHO (ed.), Ambient (outdoor) air pollution, fact sheet (4.2 million premature deaths in 2019; 99% of people above guideline levels). World Health Organization, Geneva. Observation year 2019. Accessed 2026-11-03.back
44UNVERIFIED, not opened: WHO (ed.), WHO global air quality guidelines: particulate matter, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide, 2021; the fact-sheet page did not state the guideline values and no value is used. World Health Organization, Geneva. Observation year 2021. Accessed 2026-11-03.back
7IPCC (ed.), Cities, settlements and key infrastructure, chapter 6 in Climate Change 2022: Impacts, Adaptation and Vulnerability, Contribution of Working Group II to the Sixth Assessment Report of the IPCC (downloaded chapter, executive summary read). IPCC, Geneva, 2022. Observation year 2020. Accessed 2026-11-03.back
11World Bank (ed.), Urban development overview (cities generate 80% of global GDP; infrastructure needs up to USD 2.7 trillion a year in low- and middle-income countries; slums about a quarter of urban population). World Bank, Washington. Observation year 2026 (page; individual figures undated). Accessed 2026-11-03.back
31UNVERIFIED, not opened: UNDRR (ed.), Global Assessment Report on Disaster Risk Reduction 2025; the page returned an access error and no figure is used. United Nations Office for Disaster Risk Reduction, Geneva. Observation year 2025. Accessed 2026-11-03.back
22OECD and UCLG (eds.), World Observatory on Subnational Government Finance and Investment, 2022 highlights (135 countries; 2020 data). Organisation for Economic Co-operation and Development, Paris, and United Cities and Local Governments, Barcelona. Observation year 2020. Accessed 2026-11-03.back
6IPCC (ed.), Urban systems and other settlements, chapter 8 in Climate Change 2022: Mitigation of Climate Change, Contribution of Working Group III to the Sixth Assessment Report of the IPCC (downloaded chapter, executive summary read). IPCC, Geneva, 2022. Observation year 2020. Accessed 2026-11-03.back
10WHO (ed.), Climate change, heat and health, fact sheet (about 489,000 heat-related deaths a year, 2000 to 2019; Europe summer 2022). World Health Organization, Geneva. Observation year 2019. Accessed 2026-11-03.back
5UN DESA (ed.), Sustainable Development Goal 11: make cities and human settlements inclusive, safe, resilient and sustainable (Goal page; slum population, land consumption rate, targets). United Nations, New York. Observation year 2022 (slums) and 2025 (land consumption). Accessed 2026-11-03.back
2DATA VINTAGE AFTER CLOSE: World Bank (ed.), World Development Indicators, API extract of urban population, total population, urban agglomerations, urban access to electricity, clean cooking, safely managed drinking water and sanitation, slum share (database updated 8 October 2026). World Bank, Washington. Observation year 2025 (population) and 2024 (access). Accessed 2026-11-03.back

Cite this annex

Valadbaygi, S. (Ed.). (2026). Annex A: Methodology. In Global Cities Risk and Resilience Report 2026: Baseline Edition, The State of the World’s Cities and Urban Systems. (Baseline Edition 2026, Report No. NR-SECTOR-CITIES-GLOBAL-2026-BASELINE) [Draft under review]. The Global Centre for Risk and Innovation (GCRI).

Every citation form of the whole report, BibTeX and RIS included, is on the edition home. Cite this report

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