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NASA-RioUCCRNTrainingPartnership:SeaLevelRise,UrbanHeatIslands,andWaterQuality
SEALEVELRISE—Part2:Futuresealevelandcoastalstormprojections
VivienGornitz andDanielBader
ColumbiaUniversity/NASAGoddardInstituteforSpaceStudies,Tuesday,November15,2016
HistoricalSeaLevelRiseinNYC
2Gornitz, V. Impacts of Sea Level Rise on Coastal Urban Areas
NewYorkCityPanelonClimateChange(NPCC2)§ AfterHurricaneSandy,MayorBloombergconvenedthesecondNewYorkCityPanelonClimateChange(NPCC2),January2013.
§ ClimateRiskInformation2013 providesclimatechangeprojectionsandfuturecoastalfloodriskmapsforNYC’sSpecialInitiativeforRebuildingandResiliency(SIRR).
§ BuildingtheKnowledgeBaseforClimateResiliency. NewYorkCityPanelonClimateChange2015Report.Finalreportincludeslatestfindings.§ AvailableonlineattheNewYorkAcademyofSciences
3
Solidearth/gravitation/rotation“Fingerprint”
NYCsealevelchange
Steric/Dynamicoceanchanges
GlacialIsostaticAdjustment
LandWaterStorage
Glaciermassbalance
Icesheetmassbalance
ComponentsofSLRinNPCC2scenarios
Land water storage
Causes of Sea Level Change
Vertical land motions
Mass changes
Thermal expansion
Groundwater mining,impoundment in reservoirs,
runoff, deforestation,seepage into aquifersurban
Subsidence/uplift due toglacial isostatic adjustment,tectonics
Glaciers andice sheets
Ocean water
FingerprintingGravitational, Rotational,
Isostatic
4
OverviewofNewNPCC2SeaLevelRiseandCoastalFloodMethodology
• CMIP5GCMsandIPCCRCPscenarios—oceaniccomponents:thermalexpansion(global)anddynamicseaheight(local)
• Updatedratesoficemasslossfromglaciers,smallicecaps,andicesheets(global)
• LatestGIAandgravitational/rotationalcorrections(local)• Landwaterstoragecontributionstosealevelrise(global)• CoupledsealevelriseandFEMAADCIRC/SWANmodelsimulationsoftropicalandextra-tropicalcyclonesfor100-yearfloodzones(local).
5
Massredistributionfromicelosscreatesa“fingerprint”
§ AttheBattery:• 1mSLRequivalenticelossfromGreenland=~0.6mSLR• 1mSLRfromAntarctica=~1.2mSLR
740 J. X. Mitrovica et al.
Figure 7. Normalized sea level fingerprints computed using melt models(a) G-U, (b) G-V and (c) their difference (i.e. frame b minus a). The meltmodel G-V is shown in Fig. 6(b).
respectively) the amplitude of the difference is ∼0.4, or 40 per centof the eustatic value. Closer to, but outside Antarctica, the differenceexceeds the eustatic value, and within the melt zone the differencecan be over an order of magnitude greater than the eustatic value.
4 F I NA L R E M A R K S
We have presented a comparative analysis of the sea level finger-prints of rapid ice sheet melting computed using a number of nu-merical methods and based on earth models and sea level theoriesof varying complexity.
As an example, a comparison of a pseudo-spectral calculationof the sea level change in a global (i.e. no continent) ocean due torapid melting of the WAIS with an analytic solution demonstratedthat pseudo-spectral sea level solvers, which are the most commonalgorithms for computing deglaciation-induced sea level change,converge to the correct solution (Fig. 3). Furthermore, we were ableto reproduce to within ∼1 per cent accuracy peak values of the
Figure 8. Normalized sea level fingerprints computed using melt models(a) WA-U, (b) WA-V and (c) their difference (i.e. frame b minus a). Themelt model WA-V is shown in Fig. 6(a).
sea level fingerprint associated with uniform melting of the WAISpublished by Clark & Lingle (1977) for the case of a non-rotating,1-D elastic earth model with fixed, present-day ocean geometry anda Green’s function sea level solver (Fig. 1). The agreement wasevident in comparisons with solutions computed using a pseudo-spectral solver based on both a 1-D Love number formulation anda space-domain solver based on a 3-D finite volume code for pre-dicting the Earth’s elastic response to loading.
One of the most pressing applications of fingerprint studies isthe projection of future sea level changes following the collapse ofexisting reservoirs of ice. We have presented a detailed comparisonof two recent projections involving the potential collapse of theWAIS (Bamber et al. 2009; Mitrovica et al. 2009; Gomez et al.2010) which were based on rotating earth models with evolvingshoreline geometry. The projections by Mitrovica et al. (2009) andGomez et al. (2010) are characterized by a peak far field sea levelamplification relative to the eustatic trend of ∼37 per cent, whichis significantly higher than the 25 per cent amplification factor
C⃝ 2011 The Authors, GJI, 187, 729–742Geophysical Journal International C⃝ 2011 RAS
Greenland Antarctica6
• 24CMIP5GCMs(oceaniccomponents—thermalexpansion,dynamicoceanheight)
• 2IPCCRepresentativeConcentrationPathwayscenarios:RCP4.5andRCP8.5
• 10th,25th,75th,and90th percentilesfrommodel-baseddistribution,literaturesurvey,expertjudgment
• 1ormoregridboxespermodelcoverthestudyarea• Timeslices:2020s,2050s,2080s,2100(10-yearaveragescenteredondecadalmid-point)
• Sealevelriserelativetobaseperiod2000-2004
NewYorkCityPanelonClimateChange,ClimateRiskInformation2013;BuildingtheClimateBaseforClimateResiliency2015 www.nyc.gov/planyc,www.nyc.gov/resiliency,www.ccrun.org,www.cunysustainablecities.org,www.nyas.org/Publications/Annals/
ClimateModelsandEmissionsScenarios
7
TreatmentofUncertainty
§ NPCC2uncertaintydistributionsarebasedonrangesofclimatemodeloutputsandliterature-derivedlikelihoodsfordifferentfuturegreenhousegasemissionscenarios
§ Model-basedresultsmaynotencompassthefullrangeofpossiblefutureoutcomes
8
Idealizedmodel-basedoutputdistributionfor2050ssealevelriserelativetothe2000-2004baseperiod.Basedon24globalclimatemodelsand2representativeconcentrationspathways.The10th,25th,75th,and90thpercentilesofthedistributionareillustrated.
NPCC, 2015
NewYorkCitySeaLevelRiseProjections(NPCC,2015)
Observedandprojectedsealevelrise,NewYorkCity
Sealevelriseprojectionsbycomponent,2080s(NPCC,2015)
Component Low-estimate MiddleRange High-estimate
LocalOceanHeight+Global
ThermalExpansion
15.4cm 18.1to37.0cm 50.7cm
TotalIceloss(withfingerprint) 7.6cm 14.6to46.7cm 79.0cm
---- GreenlandIce
Sheet
7.6cm 8.8to14.2cm 18.5cm
----WestAntarcticIce
Sheet
2.5cm 3.4to12.9cm 27.1cm
---- EastAntarcticIce
Sheet
-4.5cm -2.9to5.8cm 14.1cm
----GlaciersandIce
Caps
6.6cm 10.6to19.7cm 23.7cm
LandSubsidence 10.5cm 10.5to10.5cm 10.5cm
LandWaterStorage 0.04cm 1.6to5cm 6.5cm
TotalSeaLevelRise 33.5cm 44.7to99.2cm 146.7cm
2080s
Sealevelriseprojectionsbycomponent,2100(Koppetal.,2014)
RCP4.5 2100 0.06--0.15 m (GIC) (5%--95%)0.01—0.10 m (GIS)-0.09—0.38 m (AIS)-0.02—0.63 m (all ice)0.01—0.70 m (all ocean)0.02—0.08 m (LWS)0.12—0.15 m (GIA/tect.)
Total SLR 0.35—1.23 m
RCP8.5 2100 0.09—0.19 m (GIC) (5%--95%)0.02—0.17 m (GIS)-0.12—0.38 m (AIS)-0.01—0.74 m (all ice)0.05—0.98 m (all ocean)
0.02-0.08 m (LWS)0.12—0.15 m (GIA/tect.)
Total SLR 0.44—1.54 m
HistoricalStormsinNewYorkCityArea
13
NPCC2CoastalFloodHeightsandRecurrencePeriods
14
Annual Likelihood(1%Chance)ofToday’s100-yearflood
15
Coastalfloodingisverylikelytoincreaseinfrequency,extent,andheightasaresultofincreasedsealevels
Annual chance of 100-year flood (1%)
Low estimate (10th
percentile)
Middle range (25th to 75th
percentile)
High estimate (90th
percentile) 2020s 1.1% 1.1 – 1.4% 1.5%
2050s 1.4% 1.6 – 2.4% 3.6%
2080s 1.7% 2.0 – 5.4% 12.7%
NPCC2FutureCoastalFloodRiskMaps
16
FloodReturnCurves:ComparisonBetweenStaticvsHydrodynamicFloodingMethods
• “FEMA-style”floodhazardassessmentswithsealevelrise—staticvshydrodynamicmodeling
• 100-year,500-yearfloodheights;returnperiods
17
Battery
Howard Beach
Midland Beach
IncreasingNewYorkCity’sCoastalResilience
• NewLIDARmappingtoidentifyhighriskflood-proneareas• Incorporatesealevelrisedatainto FEMA’snew100-yearfloodmaps• Adaptexistingstormemergencypreparationstoclimatechange• Improvecoastaldefenses:strengthenandraiseseawalls;buildmoredikes,levees,floodgates
• Raiselandelevation,strengthenbuildingcodes,avoidnewconstructioninflood-proneareas
• Create“softedges” todampenwaveandtideenergy– re-plantnativevegetation;reduceland-seaslope
• Createseriesofparksalongwaterfrontasbufferzones• Restoreorconstructnewwetlandsandoffshorereefs• Widenbeaches,rebuildandre-vegetatebeachdunes.
19
‘Hard’CoastalDefenses
20Source: Gornitz (2013); Rising Seas Fig. 8.11
HurricaneIreneovertopsseawall,BatteryParkCity,lowerManhattan
21
SeawallconstructioninQueensfollowingHurricaneSandy
22
Creatingasoftedgeshoreline,BrooklynBridgePark,NewYorkCity
Source:DepartmentofCityPlanning,CityofNewYorkCity,2011. 23
BrooklynBridgePark,NewYorkCity
24
25
PlannedBermandPark,LowerEastSideofManhattan
BermandSeawall,WestSide,Manhattan
26
SaltMarshRestoration,JamaicaBay
27Source: Galvin Brothers, Inc. http://chl.erdc.usace.mil/Articles/7/5/4/JamaicaBay.Grasses.jpg