Primer on Sea Level Rise and Future Flooding. Doug Marcy / Russell Jackson Coastal Hazards Specialists NOAA Office for Coastal Management

Transcription

1 Primer on Sea Level Rise and Future Flooding Doug Marcy / Russell Jackson Coastal Hazards Specialists NOAA Office for Coastal Management

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3 Sea Level has Changed Throughout Geologic History

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5 1.7mm/year 2.9mm/year

6 Past, Present, and Future Forecasts Historic Proxies Gage Data Satellites NTS: Average Height of US Male = 5 10

7 Literature Review Sea Level Rise (meters) IPCC Estimates IPCC (2001, 2007, and 2013) acknowledge that there is an unknown additional potential contribution from major ice sheets that is not included in 0.96 the range shown here NRC IPCC IPCC IPCC 2013 Rahmstorf 2007 Horton 2008 Pfeffer 2008 Vermeer 2009 Jevrejeva 2010 Katsman 2011 NRC NOAA 2012 USACE 2013

8 Global Sea Level Rise Scenarios for the United States National Climate Assessment

9 Consensus Scenarios that fed the NCA 3 rd Assessment Major Ice Melt Moderate Ice Melt Today Ocean Warming Extrapolation

10 Greatest source of uncertainty? Source: NASA

11 SCENARIOS ARE trajectories of environmental change for the purpose of risk and vulnerability assessment to inform the development of robust adaptation options ARE NOT predictions or projections of what will happen ARE NOT formed under the assumption of reducing uncertainty

12 Why use multiple scenarios? Source: Global Business Network Weeks et al 2011

13 A Decision Analogy Tomorrow there is a chance of rain, but what do you have planned for tomorrow?

14 Why such a large scenario range? Higher risk tolerance: Greater flexibility to accommodate flooding Lower consequence Ability to change in near term Lower risk tolerance: Little flexibility to accommodate flooding Higher consequence Inability to change in near term

15 Sea Level is Not Rising at the Same Rate Everywhere

16 Land Motion Plays a Big Part Too

17 Local Sea Level Rise The mean sea level trend is 3.15 millimeters/year with a 95% confidence interval of +/ mm/yr based on monthly mean sea level data from 1921 to 2006 which is equivalent to a change of 1.03 feet in 100 years.

18 Local Projections - Charleston

19 Selecting a SLR Scenario (example) A 1.5 foot increase will be used for short-term, less vulnerable investment, such as a parking lot. A 2.5 foot increase will be used for more critical longer term investments, such as emergency routes and public buildings. From City of Charleston Sea Level Rise Strategy Document

20 Critical Thresholds Are Being Reached More Often

21 Recent High Tide Events

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23 Nuisance Flooding

24 Anomaly In October

25 Add Rain and You Get Worse Flooding

26 Stormwater 101 Low Tide High Tide

27 Increase in Events

28 Top Ten U.S. Areas with an Increase in Nuisance Flooding Nuisance level : Meters above mean higher high water mark Average nuisance flood days, Average nuisance flood days, Percent Increase Annapolis, Md. Baltimore, Md. Atlantic City, N.J. Philadelphia, Pa. Sandy Hook, N.J. Port Isabel, Texas Charleston, S.C. Washington, D.C. San Francisco, Calif /29/ :56 am Tide at Charleston Gauge 7.2' (observed) Mycoast.org/SC es2014/ _nuisanceflooding. html Norfolk, Va

29 10/29/ :25 am Tide at Charleston Gauge 7.4' (observed) Mycoast.org/SC ov/stories2014/ _sea levelrise.html

30 We Are One of the Poster Children human-caused-coastal-flooding

31 Documenting King Tides

32 What Are We Going To Do?

33 The Stage has Been Set to Look at Future July 2012 Oct 2012 Dec 2012 Spring 2013 Early June 2013 June 2013 Aug 2013 Spring 2014 March 2015 Flood Risks Biggert-Waters Flood Reform Bill Reestablishment of TMAC Hurricane Sandy Sea Level Rise Scenario Consensus Updating Old Flood Risk Maps New Tools to Visualize Future Flood Risk President s Climate Action Plan Sandy Rebuilding Taskforce Federal Flood Risk Management Standard Climate Data Initiative and Climate Resilience Toolkit coast.noaa.gov

34 Hurricane Sandy Turning Point? Places in NJ and NY experienced 6-7 ft of inundation above ground level. At the Battery in New York City, Sandy was estimated to be over a 1600 year event (less than % chance annually). Sandy was the second most costly hurricane to hit the U.S. (Katrina was first).

35 New Tools To Visualize and Compute Flood Risk Sea Level Rise Tool For Sandy Recovery DEMO

36 Usable science supports choices, actions The SLR Tool for Sandy Recovery was used for: 16 local laws in 2013 Natural Hazard Mitigation Plan Multi-purpose levee in Lower Manhattan Beach replenishment and dune construction Restored wetlands and a tidal barrier in Coney Island Creek ConEd rate case

37 Mapping Future Conditions Recommendation 3: Provide flood hazard products and information for coastal and Great Lakes areas that include the future effects of long-term erosion and sea/lake level rise. Major elements are: Provide guidance and standards for the development of future conditions coastal flood hazard and risk products. Incorporate local relative sea/lake level rise scenarios and long-term coastal erosion into coastal flood hazard analyses. Consider the range of potential future natural and manmade coastal changes, such as inundation and coastal erosion.

38 FFRMS Elevation and Floodplain Agencies select one of three approaches: 1. A Climate-Informed Science Approach (CISA) using bestavailable, actionable climate science, and considering other factors affecting flood risk, the investment lifetime, and the action s criticality (preferred approach where data are available) 2. Freeboard above BFE of 2 feet (standard actions) or 3 feet (critical actions) Percent-Annual-Chance (500-year) flood elevation

39 New DFIRMs

40 It s About Time! Congress has given FEMA the authority to start to evaluate how to incorporate future flood risk Recommendations have been made by TMAC Federal guidance on future global sea level rise now exists more coming New Federal investments will require a higher flood standard Agencies are developing guidance for taking into account climate change/slr (ex. DOT, USACE, DOD, EPA) Going above and beyond the current regulations and standards is now considered a best practice. Communities want to build from disasters stronger and smarter and are looking for tools and guidance for future flooding (and we are working on them).

41 Sea Level Rise and Coastal Flooding Impacts Viewer coast.noaa.gov/digitalcoast/tools/slr Displays potential future sea levels Provides simulations of sea level rise at local landmarks Communicates the spatial uncertainty of mapped sea levels Models potential marsh migration due to sea level rise Overlays social and economic data onto potential sea level rise Examines how tidal flooding will become more frequent with sea level rise

42 Coastal Flood Exposure Mapper coast.noaa.gov/digitalcoast/tools/flood-exposure

43 Steps to Resilience 1. Focus on climate stressors that threaten people, buildings, natural resources, or the economy in your area. 2. Identify specific populations, locations, and infrastructure that may be impacted by the climate problem you identified. 3. Compile a list of potential solutions, drawing on the experiences of others who have addressed similar problems. 4. Consider risks and values to analyze the costs and benefits of favored options. Select the best solution for your situation and make a plan. 5. Implement your plan and monitor your progress. As necessary, adjust your plan to move toward your desired outcomes. Be prepared to iterate, if needed. From U.S. Climate Resilience Toolkit toolkit.climate.gov

44 Robustness vs. Resilience Robust systems, designs, and projects are sturdy (Gray Infrastructure). They function and perform within specifications regardless of externals stressors. External stressors are absorbed or deflected without internal change. Resilient systems, designs, and projects adapt, adjust, and change in response to internal and external stressors (Green Infrastructure) They have response gradients and thresholds or tipping point. Their performance may shift to alternate states or regimes

45 Future Strategy for Charleston

46 Future Strategy for Charleston

47 Questions? Doug Marcy Russell Jackson