1. 3.3 Theory of Climate Change 3.4 Observations
3.1 Introduction
3.2 The IPCC Process
3.3 Theory of Climate Change
3.4 Observations
3.5 Climate Change Prediction
3.6 US Impacts
3.7 Summary

2. 3.6 US Impacts
Global Climate Change Impacts in the United States

3. Global Climate Change Impacts in the United States
How has climate already changed?
How is it likely to change in the future?
How is climate change affecting us now
where we live and work?
How is it likely to affect us in the future?
What are our options for responding?

4. This report provides information we need....
to make good decisions at the
national, regional, and local levels
so we can avoid some of the impacts we’ll be talking
about today
to be able to better
understand the
consequences of our
decisions about emissions
as well as adaptation

5. Climate changes are underway now in the U. S
Climate changes are underway now in the U.S., and are projected to grow
Temperature rise
Increase in heavy downpours
Less snow and earlier snowmelt lead to changes in river flows
Sea-level rise

6. Global Average Temperature, 1900 to 2100
Temperatures will continue to rise − by how much depends largely on the amount of heat-trapping gases in the atmosphere.
Global Average Temperature, 1900 to 2100

7. Increases in very high temperatures will have wide-ranging effects.
Higher Emissions Scenario,
Number of Days Over 100ºF
Recent Past,
Lower Emissions Scenario,

8. Heat-related illnesses and deaths are projected to increase, especially in cities.
Projected Increase in Heat-Related Deaths in Chicago

9. Observed Increases in Very Heavy Precipitation
Heavy downpours have increased across the nation and are projected to increase further.
Observed Increases in Very Heavy Precipitation
(1958 to 2007)

10. Water resources will be affected by changing precipitation patterns and increasing temperatures.
Projected Change in Precipitation by s

11. Agriculture will face challenges from increased heat, pests, water stress, diseases, and weather extremes.
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12. Florida with 3 feet of Sea-Level Rise
Coastal areas are at increasing risk from sea-level rise and storm surge.
Florida with 3 feet of Sea-Level Rise
Areas in red would be under water with a 3 foot rise in sea level, projected for this century

13. Energy and transportation infrastructure in coastal areas faces increasing risk.
Gulf Coast Area Roads at Risk from Sea-Level Rise

14. Climate change will affect many aspects of our lives as it alters the character of every region.
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15. Ocean Acidification

16. Thresholds will be crossed, leading to large changes in ecosystems.
Decreasing Habitat for Coldwater Fish
Based on a Higher Emissions Scenario WA OR ID

17. Various effects of climate change will interact, compounding and amplifying impacts.
Water and Energy Interactions
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18. Response Strategies
“Mitigation” – reducing the amount of climate change, for example, by reducing heat-trapping emissions or increasing their removal from the atmosphere
“Adaptation” – improving our ability to cope with or avoid harmful impacts or taking advantage of newly favorable conditions
Both will be needed.

19. globalchange.gov/usimpacts