Western heat, fire and grid summer

A conditional statement under stated assumptions, never a prediction.

2 min read0 figures0 tables1 noteNR-COUNTRY-USA-2026-BASELINE

Contents
  1. ·Edition home
  2. ·Executive summary
  3. 1America’s risk is coupled, not cumulative
  4. 2Key findings
  5. 3Systems and sectors at baseline
  6. 4Risks and capability
  7. 5Western heat, fire and grid summer
    1. 5.1 Assumptions
    2. 5.2 The cascade, step by step
    3. 5.3 The scenario as a table of steps
  8. 6Lenses and readings
  9. 7The 2027 agenda
  10. 8Systems in depth
  11. AMethodology
  12. BData appendix
  13. CReferences and record
  14. ·Complete edition, for print

5.1Assumptions

Scenario SCN-USA-HFG-01: what is assumed, and what is held constant.

Baseline
the 2026 reference state in this edition
Drivers
a second dry winter in the West; a multi-day heat dome; an early and intense fire season during peak demand
Analogues
2020 California rotating outages; 2021 Pacific Northwest heat dome; 2025 Los Angeles fires
Interventions
none modelled, the specification describes the unmitigated case
Run state
narrative specification; quantified Foundry run scheduled for Q1 2027

5.2The cascade, step by step

  1. 1

    CLI → WAT

    heat and low flows cut reservoir and hydro output

    2021–2022

  2. 2

    CLI → ENE

    peak demand meets thin reserves; emergency alerts

    2020 California

  3. 3

    CLI → HLT

    heat deaths and emergency visits rise

    2021 heat dome

  4. 4

    BIO → HLT

    wildfire smoke over large cities

    2020 · 2023

  5. 5

    ENE → INF

    public-safety power shut-offs to prevent ignition

    California

  6. 6

    CLI → FIN

    insured losses and further non-renewals

    20252

5.3The scenario as a table of steps

How the shock in scenario SCN-USA-HFG-01 would travel through United States’s coupled systems, step by step, under the assumptions the edition states.

StepWhat happensSource
01 Climate to waterHeat and low flows cut reservoir and hydro output. Analogue or source: 2021–2022.Edition USA, scenario SCN-USA-HFG-01, step 1
02 Climate to energyPeak demand meets thin reserves; emergency alerts. Analogue or source: 2020 California.Edition USA, scenario SCN-USA-HFG-01, step 2
03 Climate to healthHeat deaths and emergency visits rise. Analogue or source: 2021 heat dome.Edition USA, scenario SCN-USA-HFG-01, step 3
04 Biodiversity to healthWildfire smoke over large cities. Analogue or source: 2020 · 2023.Edition USA, scenario SCN-USA-HFG-01, step 4
05 Energy to infrastructurePublic-safety power shut-offs to prevent ignition. Analogue or source: California.Edition USA, scenario SCN-USA-HFG-01, step 5
06 Climate to financeInsured losses and further non-renewals. Analogue or source: 2025 [2].Edition USA, scenario SCN-USA-HFG-01, step 6

A teaching model of a conditional scenario under the edition’s stated assumptions: not a forecast, not a prediction and not a warning. Sources: United States 2026, scenario SCN-USA-HFG-01 (2026); United States 2026, references (NR-CIT-1) (2026).

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

  1. 2Munich Re (ed.), Natural disasters in 2025: NatCatSERVICE full-year figures. Munich Re, Munich, January 2026.back

Cite this chapter

Valadbaygi, S. (Ed.). (2026). Chapter 5: Western heat, fire and grid summer. In United States Systems Risk and Resilience Report 2026: The State of the United States’ Interdependent Systems (Baseline Edition 2026, Report No. NR-COUNTRY-USA-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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Sector signature

The sectors behind United States.

A reading aid: the sectors the findings run through and how strongly they depend on each other.

Select corners · hover lines6 / 15 relations

Context

Heatwave

Cooling demand peaks the grid while rivers warm; heat stress fills hospitals and wilts crops.

W · E · I · F · H · B

Sectors
4 of 6
Relations
6 of 15
Coupling
0.43 share of total

Strongest relations in play

  • Water → Energy · cooling water and hydropower0.6
  • Water → Food · irrigation0.8
  • Food → Health · nutrition0.7
  • Water → Health · drinking water and sanitation0.7
Teaching values for a typical city-region, not measurements for any place. Coupling is the summed strength of the relations in play, as a share of all fifteen.
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