National Climate Assessment Sea-Level Change Scenarios

U.S. Department of Transportation Systemic Impacts of Climate on Transportation 11 October 2012

Kevin Knuuti, P.E, D.CE. Member, NCA SLCS Team US Army Cold Regions Research and Engineering Laboratory Engineer Research and Development Center Hanover, NH

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What I Will Talk About • Historical seasea-level change • Future projections of seasea-level change – global – regional

• Multi Multi--scenario approach • Regional example (Northeast) – Primaryy tide g gauges g – Land movement – MSL vs other considerations

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Global Mean Sea Level is Rising • Past history y-g global warming g and cooling g and the associated eustatic rise and fall of sea level is cyclic

• Philosophical (and practical) question - where are we in the natural cycle and have we changed it?

• Immediate question - what is important to planning, design, operation, maintenance and sustainability?

Since the last glacial maximum (~20,000 b.p.): • sea level has risen ~120 m • 15,000-6,000 b.p. - peak rate 10 mm/yr • past 100 years ~ 1.7 mm/yr

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20th Century Global SLR Trend • Sea-level Sea level

measurements from 23 long-term tide gauge records in geologically stable environments show a rise of approximately 17 centimeters per century t ((~ 1 1.7 7 mm/year). • Source: IPCC 2007 • Updated values from Church and others

Determine local relative sea-level change trend

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Future Projections of (Global) Sea Sea--Level Change • Intergovernmental I t t l Panel P l on Climate Cli t Change Ch (IPCC)

• • • •

National Research Council Various individuals A few Federal agencies g and some states U.S. Global Change Research Program (USGCRP) - National Climate Assessment (NCA)

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Future (Global) Projections IPCC – TAR (2001) IPCC global SLR by 2100 (all units are m)

Maximum range including land-ice uncertainty

Overall

– range = 0.09 – 0.88 – central value = 0.48

Contributions – – – –

thermal = 0.110.11-.043 glacial = 0.01 0.01--0.23 Greenland = -0.02 0.02--0.09 Antarctic = -0.17 - +0.02

Envelope of all SRES model simulations Envelope of model averages

IPCC, 2001

Future (Global) Projections IPCC – AR4 (2007) mean central value = 0.343 m

range = 0.18 m – 0.59 m

IPCC, 2007

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Future (Global) Projections Recent Literature

Future (Global) Projections

We cannot predict the future so what should we do regarding seasealevel change?

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Multi--Scenario Approach Multi USACE SLR Scenarios Bracket the credible range: 0.2 – 2.0 m by 2100 Consider plausible intermediate scenarios: Scenarios considered are situation dependent and based on tolerable risk

Start year = 1992

Multi-Scenario Approach Other Scenarios Bracket the credible range: 0.2 – 2.0 m by 2100 Consider plausible intermediate scenarios: Scenarios considered are situation dependent and based on tolerable risk

Start year = 1992

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Multi--Scenario Approach Multi where are we today?

Multi--Scenario Approach Multi shapes of SLC curves

Calculating sea-level values for specific years

“b” values 0.5 – 2.71E 2.71E--5 1.0 – 7.00E7.00E-5 1.5 – 1.13E1.13E-4 2.0 – 1.56E1.56E-4

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NOTE: These values will NOT include local land elevation changes, which must be added to determine RELATIVE sea-level change

Future Projections of (Regional) Sea-Level Change USGCRP - NCA

National Climate Assessment National vs Regional SLC Projections

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New England Regional and Local Variations • NOAA/NOS/C O-OPS

• Primary Pi tide tid gauges

• Most data are available ononline E t Eastport: t

2 00 +/2.00 / 0.21 0 21 mm/yr /

Portland:

1.82 +/- 0.17 mm/yr

Boston:

2.63 +/- 0.18 mm/yr

Providence: 1.95 +/- 0.28 mm/yr New London: 2.25 +/- 0.25 mm/yr The Battery: 2.77 +/- 0.09 mm/yr

Causes of Regional and Local Sea--Level Change Variations Sea • Tectonic movement and faulting g • Isostatic rebound • Compaction of Holocene strata • Fluid withdrawals (water, gas, oil oil)) • Large basin hydrodynamic changes

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Calculating Regional and Local Sea--Level Change Sea

Northeast (select location) MSL vs Other Considerations

1% - “100 yr” 10% - “10 yr” 50% - “2 yr” 99% - “1 yr”

Linear Trends Highest: 2.4 mm/yr MHHW: 1.7 mm/yr MHW:

2.3 mm/yr

MSL:

1.8 mm/yr

MLW:

1.3 mm/yr

MLLW:

1.7 mm/yr

Lowest: 1.1 mm/yr

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Plan for Uncertainty Bracket the credible range: 0.2 – 2.0 m by 2100 Consider plausible intermediate scenarios: Scenarios considered are situation dependent and based on tolerable risk

Start year = 1992

“Education is the path from cocky ignorance to miserable uncertainty” uncertainty” Mark Twain

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thank you

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