SEA LEVEL CHANGE AND TRANSPORTATION PLANNING by Bob Dean University of Florida

1. SEA LEVEL CHANGE AND TRANSPORTATION PLANNING by Bob Dean University of Florida

2. Questions to Address (1) What is the Long-term History of Sea Level Change?(2) Is Global Sea Level Currently Rising? If so, What is the Rate?(3) Is Global Sea Level Accelerating? If so, What is the Rate?(4) Prognosis for Future Sea Level Rise Rates. (5) Relevance to ransportation System Design

3. Questions to Address(The Engineering Response) (1) Incorporate Effect in Initial Design(2) Retrofit at Some Future Time An Afterthought: Possible Role of Sunspots on Global Climate Change

4. Relative Sea Level Rise: Definitions Relative Sea Level Rise (RSLR) = Global Sea Level Rise + Local EffectsGlobal = EustaticLocal = Tectonic + Compaction + Post Glacial Rebound + Subsidence + …….

5. Components of Eustatic SLR (1)Thermal expansion of water(2) Alpine glaciers(3) Ice Sheets: Greenland, and Antartica

6. Sea Level Change Over the Last 500 Million Years

7. Sea Level Change Over the Last 1 Million Years

8. Sea Level Rise Over the Last 24,000 Years

9. Sea Level Rise Over the Last 8,000 Years

10. World Wide Distribution of Long- Term Tide Gages

11. Relative Sea Level Change Based on Tide Gage Data

12. RSL Change: Juneau, AKAn Example of Post Glacial Rebound

13. RSL Change: Adak, AKNote Tectonic Effects

14. RSL Trends in Alaska

15. Subsidence • Subsidence can be substantial exceeding the eustatic component significantlyLong Beach, CA: > 6 m due to hydrocarbon extractionTokyo: 3.5 m due to water extractionOsaka: > 2 m due to water extractionCoastal Louisiana: Up to 1 m per century due to natural and anthropogenic causes

16. Subsidence Due to Natural and Human Causes

17. Production Rates and Bottom Hole Pressure Reduction. Valentine Oil Field, LA a) Production Rates of Oil, Gas and Water b) Reduction in Bottom Hole Pressure

18. Eustatic Sea Level Rise Estimates

19. Average Sea Level Rise Over the Last 120 Years

20. Is Global Sea Level Rising? Yes. Over the Past Century, the Rate Has Been Between 1 and 2 mm/year (I Like 1.2 mm/year).A Caveat: Most Tide Gages Are Located Near Areas of Ground Water Extraction. Effect on Gage Readings?

21. Is Sea Level Rise Accelerating? Rate of CO2 Increase, Mauna Loa, HI

22. Average Global Temperature Change

23. Some Predictions and Considerations of Future Sea Level Rise, 1980’s

24. Sea Level Rise Projections (IPCC) Long-term Eustatic Rate

25. Is Sea Level Accelerating?

26. Long Term RSLR at Several Locations

27. IPCC Estimates of Future SLR

28. Probabilities of Sea Level Rise:2000 to 2200

29. Is Sea Level Accelerating? (1) There are Indications of Sea Level Acceleration Although They Are Weak and do not Appear to be Increasing(2) Probably Won’t Know About Anthropogenic Effects Definitively for 30 or More Years

30. Will Sea Level Rise Accelerate in the Future? Probably, However, the Timing and Rates are Extremely UncertainAs Support, the Predicted Rates of Acceleration Have Decreased Since 1984 When Some Early Predictions Started

31. Engineering Responses * Some Highways: Increase Protection as Need Becomes Apparent* Bridges and Other Infrastructure Less Suited for Retrofitting: Allow for RSLR in Original Design

32. Example/DiscussionCoastal Highways * Base design on predictions of local RSLR* Usually, not readily retrofitted during design life* Flooding of special concern if evacuation route* If evacuation route, design for upper limit of probabilities

33. Example/DiscussionRevetment Protecting a Coastal Highway * Several coastal engineering options for retrofitting during design life, including * Adding more and heavier armor units * Beach nourishment to reduce size of waves

34. Summary • Sea level has changed over millions of years under natural forcing • Current rates of eustatic sea level rise are between 1.2 to 2.0 mm/yr • There is not consensus of an acceleration of eustatic sea level rise nor of the role of human activity • Transportation and design should understand coastal engineering options for retrofitting during design life • Transportation planning and design should include local relative sea level rise if critical to the performance

35. Possible Role of Sunspots in Eustatic Sea Level Rise

36. Solar Forcing and Glaciation Stages

37. Sunspot History:1700 to 2006

38. Recent Sunspot Activity

39. Correlation Between Sunspot Numbers and Solar Flux

40. Yearly Sunspot Numbers:1610 to 2000

41. Reconstructed Temperature:0 to 2000 AD(Note “Little Ice Age” Period)

42. QUESTIONS?

43. Example of Acceleration Concerns of Sea Level Rates (1983)

44. Is Sea Level Rise Accelerating? Consider:and evaluate a and b from the data on the following slide. b is an acceleration term.

45. Is Sea Level Rise Accelerating? This leads to: Where Is the average of the time period over which is determined. Solving for a and b from the data yields very unrealistic results signifying that the data are not well conditioned for this purpose.

46. Engineering Response NRC Report (1984)“The Prognosis for Sea Level Rise Should Not be a Cause for Alarm or Complacency”

47. Measurement of Sea Level Change

48. Outline (1) Definitions(2) Discuss Magnitudes of Relative Sea Level Rise(3) Is the rate of sea level rise increasing(4) Engineering responses to sea level rise (NRC Report)

49. Examples of Subsidence Due to Ground Fluid Extraction