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NCA5 Logo
    • About This Report
    • Guide to the Report
    • Report Credits
    • Companion Podcast
    • Additional Resources
    • About this Report
    • Guide to this Report
    • OVERVIEW
    • Physical Science
    • 2. Climate Trends
    • 3. Earth Systems Processes
    • National Topics
    • 4. Water
    • 5. Energy
    • 6. Land
    • 7. Forests
    • 8. Ecosystems
    • 9. Coasts
    • 10. Oceans
    • 11. Agriculture
    • 12. Built Environment
    • 13. Transportation
    • 14. Air Quality
    • 15. Human Health
    • 16. Indigenous Peoples
    • 17. International
    • 18. Complex Systems
    • 19. Economics
    • 20. Social Systems and Justice
    • Regions
    • 21. Northeast
    • 22. Southeast
    • 23. US Caribbean
    • 24. Midwest
    • 25. Northern Great Plains
    • 26. Southern Great Plains
    • 27. Northwest
    • 28. Southwest
    • 29. Alaska
    • 30. Hawai'i and US-Affiliated Pacific Islands
    • Responses
    • 31. Adaptation
    • 32. Mitigation
    • Focus On
    • F1. Compound Events
    • F2. Western Wildfires
    • F3. COVID-19 and Climate Change
    • F4. Risks to Supply Chains
    • F5. Blue Carbon
    • Appendices
    • A1. Process
    • A2. Information Quality
    • A3. Scenarios and Datasets
    • A4. Indicators
    • A5. Glossary

    • All Figures
    • All Key Messages
    • View All Report Downloads
  • Art × Climate
  • NCA Atlas
  • EN ESPAÑOL
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Fifth National Climate Assessment
National Topics

The national topic chapters (Chs. 4–20) summarize current and future risks related to climate change and what can be done to reduce those risks for a variety of societal and economic sectors of the United States. This Assessment builds on the range of topics covered in NCA4 by adding two new chapters: Economics (Ch. 19) and Social Systems and Justice (Ch. 20).


  • Chapter 4. Water
  • Chapter 5. Energy Supply, Delivery, and Demand
  • Chapter 6. Land Cover and Land-Use Change
  • Chapter 7. Forests
  • Chapter 8. Ecosystems, Ecosystem Services, and Biodiversity
  • Chapter 9. Coastal Effects
  • Chapter 10. Ocean Ecosystems and Marine Resources
  • Chapter 11. Agriculture, Food Systems, and Rural Communities
  • Chapter 12. Built Environment, Urban Systems, and Cities
  • Chapter 13. Transportation
  • Chapter 14. Air Quality
  • Chapter 15. Human Health
  • Chapter 16. Tribes and Indigenous Peoples
  • Chapter 17. Climate Effects on US International Interests
  • Chapter 18. Sector Interactions, Multiple Stressors, and Complex Systems
  • Chapter 19. Economics
  • Chapter 20. Social Systems and Justice

Likelihood

Virtually Certain Very Likely Likely As Likely as Not Unlikely Very Unikely Exceptionally Unlikely
99%–100% 90%–100% 66%–100% 33%–66% 0%–33% 0%–10% 0%–1%

Confidence Level

Very High High Medium Low
  • Strong evidence (established theory, multiple sources, well-documented and accepted methods, etc.)
  • High consensus
  • Moderate evidence (several sources, some consistency, methods vary and/or documentation limited, etc.)
  • Medium consensus
  • Suggestive evidence (a few sources, limited consistency, methods emerging, etc.)
  • Competing schools of thought
  • Inconclusive evidence (limited sources, extrapolations, inconsistent findings, poor documentation and/or methods not tested, etc.)
  • Disagreement or lack of opinions among experts

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