National Climate Assessment Sea-Level Change Scenarios

Transcription

1 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 1 What I Will Talk About Historical sea-level change Future projections of sea-level change global regional Multi-scenario approach Regional example (Northeast) Primary tide gauges g Land movement MSL vs other considerations Page 1

2 Global Mean Sea Level is Rising Past history - global warming and cooling 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 Page 2

3 20 th Century Global SLR Trend Sea-level measurements from 23 long-term tide gauge records in geologically stable environments show a rise of approximately 17 centimeters per century (~ 1.7 mm/year). Source: IPCC 2007 Updated values from Church and others Determine local relative sea-level change trend 5 Future Projections of (Global) Sea-Level Change Intergovernmental t Panel on Climate Change (IPCC) National Research Council Various individuals A few Federal agencies and some states U.S. Global Change Research Program (USGCRP) - National Climate Assessment (NCA) Page 3

4 Future (Global) Projections IPCC TAR (2001) IPCC global SLR by 2100 (all units are m) Overall range = central value = 0.48 Contributions thermal = glacial = Greenland = Antarctic = Envelope of all SRES model simulations Envelope of model averages Maximum range including land-ice uncertainty IPCC, 2001 Future (Global) Projections IPCC AR4 (2007) mean central value = m range = 0.18 m 0.59 m IPCC, 2007 Page 4

5 Future (Global) Projections Recent Literature Future (Global) Projections We cannot predict the future so what should we do regarding sea- level change? Page 5

6 Multi-Scenario Approach USACE SLR Scenarios Bracket the credible range: 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: m by 2100 Consider plausible intermediate scenarios: Scenarios considered are situation dependent and based on tolerable risk Start year = 1992 Page 6

7 Multi-Scenario Approach where are we today? Multi-Scenario Approach shapes of SLC curves Calculating sea-level values for specific years b values E E E E-4 NOTE: These values will NOT include local land elevation changes, which must be added to determine RELATIVE sea-level change Page 7

8 Future Projections of (Regional) Sea-Level Change USGCRP - NCA National Climate Assessment National vs Regional SLC Projections Page 8

9 New England Regional and Local Variations NOAA/NOS/C O-OPSOPS Pi Primary tide gauges Most data are available on- line Eastport: t / mm/yr Portland: / mm/yr Boston: / mm/yr Providence: / mm/yr New London: / mm/yr The Battery: / mm/yr Causes of Regional and Local Sea-Level Change Variations Tectonic movement and faulting Isostatic rebound Compaction of Holocene strata Fluid withdrawals (water, gas, oil) Large basin hydrodynamic changes Page 9

10 Calculating Regional and Local Sea-Level Change Northeast (select location) MSL vs Other Considerations Linear Trends 1% yr 10% - 10 yr 50% - 2 yr 99% - 1 yr 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 Page 10

11 Plan for Uncertainty Bracket the credible range: 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 Mark Twain Page 11

12 thank you Page 12