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Dry, hot summer across the Colorado and Rio Grande basins and the southern grids

A conditional statement under stated assumptions, never a prediction.

2 min read0 figures0 tables3 notesNR-REGIONAL-NAM-2026-BASELINE

Contents
  1. ·Edition home
  2. ·Executive summary
  3. 1North America’s risk travels through shared rivers, grids and pipelines
  4. 2Key findings
  5. 3Systems and sectors at baseline
  6. 4Risks and capability
  7. 5Dry, hot summer across the Colorado and Rio Grande basins and the southern grids
    1. 5.1 Assumptions
    2. 5.2 The cascade, step by step
    3. 5.3 The scenario as a table of steps
  8. 6Readings from the other desks
  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-NAM-DRY-01: what is assumed, and what is held constant.

Baseline
the 2026 reference state in this edition
Drivers
an extended heat wave in a dry year, with low reservoir levels and high power demand
Analogues
Colorado River decision record19; Canadian fire season 202321; reservoir and drought records at the close not bound
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

    low snowpack and flow cut reservoir inflow on shared rivers

    decision record 202619

  2. 2

    CLI → HLT

    heat and smoke raise hospital stays and deaths

    no analogue bound

  3. 3

    ENE → INF

    peak cooling demand coincides with constrained hydropower and gas supply

    gas exports 202525

  4. 4

    INF → all

    a grid or pipeline fault spreads across a connected system

    no analogue bound

  5. 5

    HLT → FIN

    losses fall on households, insurers and budgets

    loss series not bound

  6. 6

    FIN → recovery

    rebuilding slows where cover is thin

    loss series not bound

5.3The scenario as a table of steps

How the shock in scenario SCN-NAM-DRY-01 would travel through North America’s coupled systems, step by step, under the assumptions the edition states.

StepWhat happensSource
01 Climate to waterLow snowpack and flow cut reservoir inflow on shared rivers. Analogue or source: decision record 2026 [19].Edition REG-NAM, scenario SCN-NAM-DRY-01, step 1
02 Climate to healthHeat and smoke raise hospital stays and deaths. Analogue or source: no analogue bound.Edition REG-NAM, scenario SCN-NAM-DRY-01, step 2
03 Energy to infrastructurePeak cooling demand coincides with constrained hydropower and gas supply. Analogue or source: gas exports 2025 [25].Edition REG-NAM, scenario SCN-NAM-DRY-01, step 3
04 Infrastructure to allA grid or pipeline fault spreads across a connected system. Analogue or source: no analogue bound.Edition REG-NAM, scenario SCN-NAM-DRY-01, step 4
05 Health to financeLosses fall on households, insurers and budgets. Analogue or source: loss series not bound.Edition REG-NAM, scenario SCN-NAM-DRY-01, step 5
06 Finance to recoveryRebuilding slows where cover is thin. Analogue or source: loss series not bound.Edition REG-NAM, scenario SCN-NAM-DRY-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: North America 2026, scenario SCN-NAM-DRY-01 (2026); North America 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. 19U.S. Bureau of Reclamation (ed.), Post-2026 Colorado River reservoir operations (page updated 3 September 2026: draft EIS 9 January 2026, final EIS 31 July 2026, record of decision 21 August 2026, 2007 interim guidelines and 2019 drought contingency plans expiring at the end of 2026). Reclamation, Washington DC. Observation year 2026. Accessed 2026-11-03.back
  2. 21Natural Resources Canada (ed.), Forest fires: the 2023 season (more than 14.6 million hectares, more than 6,800 fires, more than 230,000 evacuations; typical year more than 2.1 million hectares). Government of Canada, Ottawa. Observation year 2023. Accessed 2026-11-03.back
  3. 25U.S. Energy Information Administration (ed.), U.S. natural gas pipeline exports by country (Mexico 2,422,839 and Canada 1,033,487 million cubic feet in 2025). EIA, Washington DC. Observation year 2025. Accessed 2026-11-03.back

Cite this chapter

Valadbaygi, S. (Ed.). (2026). Chapter 5: Dry, hot summer across the Colorado and Rio Grande basins and the southern grids. In North America Regional Systems Risk and Resilience Report 2026: Baseline Edition, The State of North America’s Interdependent Systems. (Baseline Edition 2026, Report No. NR-REGIONAL-NAM-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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