- United Kingdom 2026
- Chapter 1
Britain’s risk is coupled, not cumulative
Part I describes systems and their couplings. It assesses no authority and ranks no nation or region.
Contents
- ·Edition home
- ·Executive summary
- 1Britain’s risk is coupled, not cumulative
- 2Key findings
- 3Systems and sectors at baseline
- 4Risks and capability
- 5Hot, dry summer in southern England
- 6Lenses and readings
- 7The 2027 agenda
- 8Systems in depth
- AMethodology
- BData appendix
- CReferences and record
- ·Complete edition, for print
1.1The questions this part answers
Key questions
- Where is Canada’s risk concentrated, and in which systems?
- Which couplings carry shocks from one system to the next?
- Which capabilities hold under compound stress, and which are only documented?
- What must the 2027 programme measure first?
In this part
- Narrative
- Headline finding
- Lead figure
- Twelve-domain reading
- Sector screens
- Dependency matrix
- Risk objects
- Capability ladder
- Scenario
- Three lenses
- Portfolio
1.2The argument
The United Kingdom’s climate risks are usually discussed one at a time: a heatwave, a flood, a drought, a storm. This baseline reads them as one coupled system. On 19 July 2022 temperatures reached 40.3 °C for the first time28; the same summer brought drought, hosepipe bans, grassland fires and rail speed restrictions, and about 2,985 heat-associated deaths in England11.
The forcing is already measurable. 2022 was the first year with a UK mean temperature above 10 °C29, and the third climate risk assessment identified 61 risks and opportunities from climate change, eight of them priorities for action45. The Climate Change Committee has repeatedly found adaptation planning behind the pace of risk6.
Water sits at the centre of the coupling. About 6.3 million properties in England are in areas at risk of flooding, potentially around 8 million by 20508, while England faces a public water-supply shortfall of nearly 5 billion litres a day by 2055 without new action9. Storm overflows spilled more than 460,000 times in 202310, linking heavy rain to river quality and health.
The energy system has changed fastest. Territorial emissions fell to 373 Mt CO₂e in 2024, 53% below 1990, and the last coal-fired power station closed in September 2024118. The Clean Power 2030 plan sets out a largely clean electricity system by the end of the decade1617. Electrification makes the grid more central, and its single points of failure more consequential, as the substation fire that closed Heathrow in March 2025 showed19.
Food and nature carry slower but deeper exposures. The UK produces around 60% of the food it consumes, so import and energy-price shocks pass quickly to households14. Studied species have declined in abundance by 19% on average since 1970, and one in six is at risk of extinction in Great Britain15, weakening the ecosystems that regulate floods and water quality.
This edition therefore treats British risk as a property of couplings, between heat, water, grids, food and nature, rather than a list of separate hazards. The matrix, risk objects, capability ladder and scenario that follow ask where a shock travels next and who holds the capability to stop it.
Emissions have more than halved since 1990, driven by the power sector. Transport is now the largest emitting sector, about 30% of the total1.
| Item | Bar, scaled to the largest value | Value |
|---|---|---|
| 1990 | 790 | |
| 2023 | 384 | |
| 2024 | 373 |
Source: as cited in the note to this figure. Year 2024.
Figure ID FIG-COUNTRY-GBR-2026-BASELINE-01-003
1.3Twenty couplings between five systems
The United Kingdom matrix types the twenty couplings between the five core systems. Strengths are Nexus estimates from the cited evidence and analogue events; they set the starting graph that the Q1 2027 Foundry cut will test.
Each line is one coupling from one system to another, drawn by the strength the edition assigns. Strengths are Nexus estimates from the cited evidence and analogue events.
- Strong
- Moderate
- Weak
Source: this edition’s coupling matrix (Table 1.1); status Estimated.
| From, to | WAT | ENE | FOO | HLT | BIO |
|---|---|---|---|---|---|
| WAT Water | · | MODERATE cooling · hydro in Scotland | STRONG irrigation · rain-fed yield | MODERATE drinking water | STRONG flows · wetlands |
| ENE Energy | MODERATE pumping · treatment | · | STRONG fuel · fertiliser · cold chain | STRONG facility power · cooling | MODERATE reservoirs · land use |
| FOO Food | MODERATE withdrawals · nutrients | WEAK biofuel feedstock | · | STRONG nutrition · food safety | STRONG land conversion |
| HLT Health | WEAK workforce | WEAK workforce | MODERATE labour · disease | · | WEAK residues |
| BIO Biodiversity | STRONG regulation · filtration | MODERATE fire on lines · biomass | STRONG pollination · soils | MODERATE zoonoses · smoke | · |
| Strength: strong, moderate or weak; a Nexus estimate (status Estimated) from cited evidence and analogue events. The scale is defined in Annex A. | |||||
Transmission paths
- 01
CLI → WAT → HLT
Heat and drought strain supply and river quality while health demand peaks.
Reported summer 202211
- 02
ENE → INF → DAT
A single substation failure halts an airport and dependent services.
Reported Heathrow, March 202519
- 03
CLI → WAT → FIN
Surface-water flooding lands on households with costly cover.
Inferred NaFRA28
- 04
ENE → FOO
Energy and import prices pass into food prices.
Inferred 2022 price shock14
- 05
WAT → BIO
Storm overflows and low flows degrade rivers.
Reported 2023 spills10
1.4Reinforcing loops
A shock entering either system of a loop can return amplified through the other.
| Loop | First direction | Second direction |
|---|---|---|
| WAT and BIO | Water to biodiversity: flows · wetlands | Biodiversity to water: regulation · filtration |
| FOO and BIO | Food to biodiversity: land conversion | Biodiversity to food: pollination · soils |
| A causal-loop reading of the matrix (Sterman, Business Dynamics, 2000): structural, from estimated strengths, not a measured feedback. | ||
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
- 28Met Office (ed.), “Record high temperatures verified” (40.3 °C at Coningsby, 19 July 2022). Met Office, Exeter, 2022.back
- 11UK Health Security Agency (ed.), Heat Mortality Monitoring Report: 2022. UKHSA, London, 2023.back
- 29Met Office (ed.), “2022: the UK’s warmest year on record.” Met Office, Exeter, January 2023.back
- 4Climate Change Committee (ed.), Independent Assessment of UK Climate Risk: Advice to Government for the UK’s Third Climate Change Risk Assessment (CCRA3). CCC, London, 2021.back
- 5HM Government (ed.), UK Climate Change Risk Assessment 2022. HM Government, London, January 2022.back
- 6Climate Change Committee (ed.), Progress in Adapting to Climate Change: 2025 Report to Parliament. CCC, London, 2025.back
- 8Environment Agency (ed.), National Assessment of Flood and Coastal Erosion Risk in England 2024. Environment Agency, Bristol, December 2024.back
- 9Environment Agency (ed.), National Framework for Water Resources 2025. Environment Agency, Bristol, 2025.back
- 10Environment Agency (ed.), Event Duration Monitoring: storm overflows annual data 2023. Environment Agency, Bristol, 2024.back
- 1Department for Energy Security and Net Zero (ed.), 2024 UK Greenhouse Gas Emissions, Final Figures. DESNZ, London, 5 February 2026.back
- 18Department for Energy Security and Net Zero (ed.), “End of coal power”, closure of Ratcliffe-on-Soar power station. Press release, London, 30 September 2024.back
- 16Department for Energy Security and Net Zero (ed.), Clean Power 2030 Action Plan: A New Era of Clean Electricity. DESNZ, London, December 2024.back
- 17National Energy System Operator (ed.), Clean Power 2030: Advice on Achieving Clean Power for Great Britain by 2030. NESO, Warwick, November 2024.back
- 19National Energy System Operator (ed.), North Hyde substation fire: review of the 21 March 2025 outage. NESO, Warwick, 2025.back
- 14Department for Environment, Food and Rural Affairs (ed.), United Kingdom Food Security Report 2024. DEFRA, London, December 2024.back
- 15State of Nature Partnership (ed.), State of Nature 2023. State of Nature Partnership, UK, 2023.back