- United States 2026
- Chapter 8
Systems in depth
One section per system: its state at evidence close, its exposures and what the operational series will watch.
Contents
- ·Edition home
- ·Executive summary
- 1America’s risk is coupled, not cumulative
- 2Key findings
- 3Systems and sectors at baseline
- 4Risks and capability
- 5Western heat, fire and grid summer
- 6Lenses and readings
- 7The 2027 agenda
- 8Systems in depth
- AMethodology
- BData appendix
- CReferences and record
- ·Complete edition, for print
8.1Water, the baseline system chapter
America’s water is ample in total and tight where growth is fastest. Power plants and farms take most withdrawals, and the West is in structural shortage.
| Component | State | Evidence | Status |
|---|---|---|---|
| Withdrawals | thermoelectric 41%, irrigation 37%, public supply 12% | 7 | Reported |
| Western shortage | first Colorado River shortage declared in 2021 | 8 | Reported |
| Groundwater | High Plains and Central Valley depletion | 7 | Inferred |
| Drought | tracked weekly nationwide | 17 | Reported |
| Service access | tribal and rural gaps not consolidated | , | Expert input |
Couplings into other systems
- WAT → ENE cooling and hydro
- WAT → FOO irrigation
- WAT → HLT drinking water
- BIO → WAT watershed regulation
Evidence to bind in 2027
- aquifer levels and recharge
- post-2026 Colorado allocation
- tribal water access
Related editions
- REG-NAM North America
- GLB Global Systems
- GS-01 Water
- GS-02 Energy
- GS-05 Finance
- XT-01 AI
8.2Energy, the baseline system chapter
A gas-led electricity system with growing renewables faces two pressures at once: extremes of heat and cold, and fast new load from data centres.
| Component | State | Evidence | Status |
|---|---|---|---|
| Generation mix | gas about 43%, nuclear about 18%, growing renewables | 5 | Reported |
| Reliability | reserve margins thin in some regions | 32 | Reported |
| Extremes | 2021 cold-weather failures across Texas and the South Central US | 31 | Reported |
| New load | data centres 4.4% in 2023, 6.7–12% projected for 2028 | 6 | Reported |
| Policy | clean-energy credits amended in 2025 | 29 | Reported |
Couplings into other systems
- ENE → WAT pumping and treatment
- ENE → HLT cooling and care
- AIC → ENE data-centre load
Evidence to bind in 2027
- reliability margins under compound heat
- gas–power interdependence in winter
Related editions
- REG-NAM North America
- GLB Global Systems
- GS-01 Water
- GS-02 Energy
- GS-05 Finance
- XT-01 AI
8.3Food and agrifood, the baseline system chapter
The United States is one of the world’s largest food producers and exporters, yet 13.5% of its households were food insecure in 2023.
| Component | State | Evidence | Status |
|---|---|---|---|
| Production | large grain, oilseed and livestock output | 22 | Reported |
| Irrigation | depends on depleting aquifers in key regions | 7 | Inferred |
| Access | 13.5% of households food insecure | 11 | Reported |
| Trade | export markets exposed to tariff changes | , | Inferred |
| Drought | Plains and Western production exposed | 17 | Reported |
Couplings into other systems
- WAT → FOO irrigation
- ENE → FOO inputs and cold chain
- FOO → TRD exports
- FOO → HLT nutrition
Evidence to bind in 2027
- aquifer dependence of production
- food access after disasters
Related editions
- REG-NAM North America
- GLB Global Systems
- GS-01 Water
- GS-02 Energy
- GS-05 Finance
- XT-01 AI
8.4Health and One Health, the baseline system chapter
Heat is the fastest-growing climate–health risk. Grid failures turn weather into health emergencies, and smoke reaches cities far from fire.
| Component | State | Evidence | Status |
|---|---|---|---|
| Heat | record heat deaths in 2023 | 9 | Reported |
| Cold and outages | deaths in the 2021 Texas grid failure | 16 | Reported |
| Smoke | wildfire smoke over large cities | 3 | Reported |
| Surge capacity | not consolidated nationally | , | Expert input |
| One Health | zoonotic risks tracked by federal agencies | 3 | Inferred |
Couplings into other systems
- CLI → HLT heat and smoke
- ENE → HLT power for care and cooling
- FOO → HLT nutrition
Evidence to bind in 2027
- heat surge capacity in large metros
- cooling access for at-risk households
Related editions
- REG-NAM North America
- GLB Global Systems
- GS-01 Water
- GS-02 Energy
- GS-05 Finance
- XT-01 AI
8.5Biodiversity and ecosystems, the baseline system chapter
Many of the country’s species are at risk, and wildfire, land use and water stress are the fastest-changing pressures.
| Component | State | Evidence | Status |
|---|---|---|---|
| Species | about 40% of animal species at risk of extinction | 10 | Reported |
| Plants | about 34% of plant species at risk | 10 | Reported |
| Fire | larger and more destructive fires in the West | 3 | Reported |
| Freshwater | river and wetland ecosystems under water stress | 3 | Inferred |
| Services | watershed regulation, pollination, carbon storage | 26 | Inferred |
Couplings into other systems
- BIO → WAT watershed regulation
- BIO → FOO pollination
- CLI → BIO fire and heat
Evidence to bind in 2027
- ecosystem condition indicators
- species trends by region
Related editions
- REG-NAM North America
- GLB Global Systems
- GS-01 Water
- GS-02 Energy
- GS-05 Finance
- XT-01 AI
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
- 7C. A. Dieter, M. A. Maupin, R. R. Caldwell et al., Estimated Use of Water in the United States in 2015, Circular 1441. U.S. Geological Survey, Reston, VA, 2018.back
- 8U.S. Bureau of Reclamation (ed.), “Reclamation announces 2022 operating conditions for Lake Powell and Lake Mead.” News release, Washington, DC, August 2021.back
- 17National Drought Mitigation Center (ed.), U.S. Drought Monitor. University of Nebraska–Lincoln, retrieved 2026-09-30.back
- 5U.S. Energy Information Administration (ed.), “Electricity in the United States” and Electric Power Monthly. EIA, Washington, DC, retrieved 2026-09-30.back
- 6A. Shehabi, S. J. Smith, A. Hubbard et al., 2024 United States Data Center Energy Usage Report. Lawrence Berkeley National Laboratory, Berkeley, CA, December 2024.back
- 16Texas Department of State Health Services (ed.), February 2021 Winter Storm-Related Deaths, Texas. DSHS, Austin, TX, 2021.back
- 32North American Electric Reliability Corporation (ed.), 2025 Summer Reliability Assessment. NERC, Atlanta, GA, 2025.back
- 31Federal Energy Regulatory Commission and North American Electric Reliability Corporation (eds.), February 2021 Cold Weather Outages in Texas and the South Central United States. FERC and NERC, Washington, DC, 2021.back
- 29U.S. Congress (ed.), Inflation Reduction Act of 2022, Public Law 117-169, as amended by Public Law 119-21 (2025). Washington, DC.back
- 11USDA Economic Research Service (ed.), Household Food Security in the United States in 2023. USDA ERS, Washington, DC, December 2024.back
- 22USDA National Agricultural Statistics Service (ed.), 2022 Census of Agriculture. USDA NASS, Washington, DC, 2024.back
- 9J. T. Howard, N. Androne, K. C. Alcover and A. R. Santos-Lozada, “Trends of heat-related deaths in the US, 1999–2023,” JAMA, vol. 332, no. 14, pp. 1203–1204, 2024.back
- 3A. R. Crimmins, C. W. Avery, D. R. Easterling, K. E. Kunkel, B. C. Stewart and T. K. Maycock (eds.), Fifth National Climate Assessment. U.S. Global Change Research Program, Washington, DC, 2023.back
- 10NatureServe (ed.), Biodiversity in Focus: United States Edition. NatureServe, Arlington, VA, 2023.back
- 2Munich Re (ed.), Natural disasters in 2025: NatCatSERVICE full-year figures. Munich Re, Munich, January 2026.back
- 26P. D. McElwee, P. A. Harrison, T. L. van Huysen et al. (eds.), Thematic Assessment Report on the Interlinkages among Biodiversity, Water, Food and Health. IPBES secretariat, Bonn, 2024. doi:10.5281/zenodo.13850054. doi:10.5281/zenodo.13850054back