Turn and Face the Strange: Economic Impacts of Climate Change Sea Level Rise and Coastal Flooding E2Tech Forum June 21, 2018

Transcription

1 Turn and Face the Strange: Economic Impacts of Climate Change Sea Level Rise and Coastal Flooding E2Tech Forum June 21, 2018 Peter A. Slovinsky, Marine Geologist Maine Geological Survey Image from Chebeague.org

2 What causes the global sea level changes that we are seeing today? Volumetric Increase 10% 50% 40% modified from Griggs, 2001 Thermal Expansion

3 Global Sea Level Rise Driving Factors: Volumetric Increase (melting of land-based ice sheets and glaciers) Glaciers (m of water equivalent thickness) 30 well-studied glaciers have decreased in average thickness by 60 feet

4 Global sea level rise average over the last century: 1.8 mm/year Global Sea Level Rise Driving Factors: Thermal Expansion (expansion of the water column due heating) Ocean Heat (10 22 joules) compared with average Global sea level (mm) as difference from 1990

5 Last 20 yrs: 3.1 mm/yr (1.2 per decade) Combined independent totals from thermal expansion and glacier/land based ice sheet input match satellite measurements adapted from Figure 3.15a in State of the Climate in 2016

6 Locally, sea level is rising in the long term P.A. Slovinsky, Maine Geological Survey, February 2, 2018

7 is rising faster in the short term and can rise abruptly P.A. Slovinsky, Maine Geological Survey, February 2, 2018

8 Sea level can also change abruptly. Portland saw an average of approximately 5 higher than normal tides in the summer of 2009, and, especially in winter of This was the highest along the whole east coast.

9 Five of the highest monthly sea levels since 1912 occurred in winter We suspect similar conditions likely occurred in winter Higgins Beach, Scarborough, April 7, 2010 P.A. Slovinsky

10 Adapted from NOAA Technical Report NOS CO-OPS 083, January, 2017 and sea level is expected to continue to rise. Global Mean Sea Level Scenarios to ft Global Mean Sea Level (m) Tide gauge data Satellite data Scenarios 6.6 ft 4.9 ft 3.3 ft 1.6 ft 1.0 ft

11 and potentially rise higher than global averages. Relative Sea Level Scenarios to ft Relative Sea Level Change (m) Scen Interm Int-High ft 6.0 ft 3.8 ft 1.6 ft 1.0 ft Adapted from using Portland tide gauge and NOAA 2017 regional scenarios for New England.

12 What about storm tides and storm surges?

13 So what is storm surge and storm tide? Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide (NHC).

14 The Battery, NY during Superstorm Sandy Predicted Tide = 1.9 ft NAVD Storm Tide = 11.3 ft NAVD Storm Surge = 9.4 ft Storm Tide Storm Surge Predicted Tide

15 Portland Storm Tides Statistics Recurrence Interval % Annual Chance Storm Tide (ft, MLLW) 1 100% % % % % % 13.7 Highest recorded storm tide was 14.1 feet on 2/7/1978 Updated 11/17/17, P.A. Slovinsky, MGS

16 Portland Storm Tides Statistics Recurrence Interval % Annual Chance Storm Tide (ft, MLLW) 1 100% % % % 13.2 <1 foot difference! 50 2% % 13.7 Highest recorded storm tide was 14.1 feet on 2/7/1978 Updated 11/17/17, P.A. Slovinsky, MGS

17 25 highest annual water levels (1912 to 2018)

18 King Tide October 25, 2016 A. Sherwin, MCP Flood Stage = 12 ft MLLW

19 Changes in Annual Flooding Frequency with SLR Portland, ME Using data from Scenario Flood Stage # times per % of high (ft, MLLW) year tides Existing % +1 ft SLR % +2 ft SLR % Based on this, there could potentially be a tenfold increase in the frequency of flooding in Portland with 1 foot of sea level rise.

20 Sea Level Rise and Storm Surge Summaries Latest scenarios for SLR (using the intermediate to intermediate high relative scenarios from NOAA 2017): Short Term: approximately ft by 2050 Long Term: 3-6 ft but potentially more by 2100; Sea level rise increases both the frequency and duration of annual tidal and storm-driven flood events. Abrupt short-term sea level changes do occur, and can have significant impacts on storm levels and beach erosion. Maine has been extremely lucky in the past due to its large tidal range, which lowers the probability of a large surge corresponding with a high tide.

21 Some of Maine s adaptation challenges Home-rule state General lack of financial and political support Work has been based on solely on individual community or regional interest Patchwork approach to resiliency Much has focused on low hanging fruit approaches to dealing with flooding and sea level rise

22 Implementation of locally-derived and driven adaptation strategies: Revising or developing ordinance or plan language (Saco, Damariscotta, York, Bowdoinham, South Portland) Adapting waterfront infrastructure (Damariscotta, Boothbay Harbor) Adapting critical infrastructure (Old Orchard Beach, Ogunquit, Wiscasset, Boothbay Harbor) Elevating critical roads (Kennebunkport)

23 Adaptation Strategy: Incorporate more freeboard into municipal floodplain ordinances P.A. Slovinsky, MGS Saco, Damariscotta and South Berwick made ordinance changes to increase freeboard to three feet above the 100- year Base Flood Elevation (BFE).

24 Low Hanging Fruit : Flood Insurance Premium Benefits Annual A-zone policy: $1,556 Annual A-zone policy: $509 Scenario V-zone A-zone Annual Policy Savings (%) 30-year savings Annual Policy Savings (%) 30-year savings No Freeboard $7,747 $0 (0%) $0 $1,556 $0 (0%) $0 1 ft freeboard $5,331 $2,416 (31%) $72,480 $799 $757 (49%) $22,710 2 ft freeboard $3,648 $4,099 (53%) $122,970 $574 $982(63%) $29,460 3 ft freeboard $2,635 $5,112 (66%) $153,360 $509 $1,047(67%) $31,410 Based on 2012 rates for a one-floor residential structure, no basement, post-firm, $1,000 deductible with $250,000 coverage and $100,000 contents. Flood policy rating quotes provided t by Chalmers Insurance Group,

25 Waterfront Infrastructure Vulnerability and Adaptation studies

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28 Adapting critical infrastructure to flooding Protecting current facilities R. Faunce, LCRPC Thinking about the future (NEIWPCC standards)

29 Elevating critical road infrastructure Dyke Road and Kings Highway, Kennebunkport

30 Elevating critical road infrastructure Dyke Road and Kings Highway, Kennebunkport

31 Sea Level Rise and Storm Surge Mapping HAT, +1, +2, +3.3, +6 feet

32 Sea, Lake and Overland Surges from Hurricanes

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34 Thank you! Peter A. Slovinsky, Marine Geologist Maine Geological Survey (207)