sea-level change: past, present, future · 2014-10-28 · long-term 100 vs. 250 m!! myr-scale...
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View of NY harbor from the !JOIDES Resolution in an ice-free world (64 m rise)!
Onshore ODP-EAR-ICDP!Legs 150X & 174AX !
Kenneth G. Miller (& friends)!Dept. Earth & Planetary Sci., Rutgers University, AAPG Distinguished Lecturer!
ODP/IODP!Legs 150 & 174A!
Sea-level Change: Past, Present, Future!
My shore house!Dec. ‘91 nor’easter!
NJ shallow shelf!IODP Exp 313, L/B Kayd!
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2008 (Miller)
3 ft sea-level rise ~2100 CE 1 ft sea-level rise ~2040 CE
Oct. 31, 2012 (AP) N
N
N N
Ship Bottom, Long Beach Island, NJ
http://slrviewer.rutgers.edu
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Causes of global average sea-level change Global average sea level (=eustasy) raised by:
• Temperature: warming expands seawater (less dense) • Ice volume: melt ice (mountain glaciers & ice sheets) • Ocean volume (ocean crust production, etc.; 107 yr)
Department of Earth and Planetary Sciences
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Causes of relative sea-level change Regional sea level:
1) Subsidence (sinking) or uplift tectonics (e.g., Alaska uplift) includes glacial isostatic adjustment (GIA)
2) Oceanographic effects (e.g., El Nino, Gulf Stream changes)
Local sea level: Compaction due to natural processes & water or oil extraction
Department of Earth and Planetary Sciences
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Un-Vailing eustasy: An ad-Haq hypothesis?!Vail et al.(1977)! Haq et al. (1987)!
400 m! m!!
160 m m!!
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How is sea-level change reconstructed?!
1) Date the record!!
2) Determine changes in water depth (local)!
!!!3) Remove local and regional subsidence/uplift !
Challenge!
Artful!
Reference frame?!
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Geologic approaches studying sea-level change!
• Drill reefs on atolls and uplifted terraces!e.g., Barbados, Tahiti, N. Guinea, Sunda shelf, Enewetak!
• Drill continental margins!e.g., IODP New Jersey offshore & onshore, !New Zealand, !Bahamas, !NE Australia!
COSODII (1987), Sea level workshop (1990), ODP-SLWG (1992), IODP-ICDP-DOSECC workshop (2008) !
• Drill deep-sea sections glacioeustatic proxy!e.g., δ18O, Mg-Ca with astronomical time control!
D/V Ranger!
JOIDES Resolution!
L/B Kayd!Sandy Hook NJ!Oct. 2014!
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Sea-level records (Miller et al., 2011)!
Above: scaled deep sea δ18O!Left: backstripped onshore core!
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NJ/MAT sea-level transect (Legs 150, 150X, 174A, 174AX, 313)!Develop eustatic estimates & evaluate stratigraphic response!
excellent seismic grid; simple tectonics (thermal);!excellent age control (Sr-isotope, bio-, magneto-stratigraphy); paleodepth control (litho- & bio- facies); previous data!
29!27 28!
Why NJ: !
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New Jersey outcrop sequence boundary!
Campanian/Maastrichtian unconformity!Matawan, NJ�
Sequence: stratigraphic unit of relatively conformable, genetically related strata bounded by unconformities and correlative surfaces associated with baselevel lowering (tectonic & eustatic)!
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Identifying marine sequence boundaries in cores!Physical evidence
• Sharp unconformable contacts • Lag gravels, phosphorites • Shell beds/hash • Rip-up clasts • Extensive burrowing and bioturbation • Geophysical log characteristics • Overstepping of lithofacies successions • Facies succession (model dependent) • Dramatic paleodepth changes
Must show geographic distribution (not local surface)
Temporal Hiatuses • Sr-isotopic stratigraphy • Biostratigraphy (e.g., planktonic
foraminiferal zones)
Oligocene!(~ 26.6 Ma)!
Mid-Miocene!(M4)!(18.0-18.4 Ma)!
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Seismic profiles image unconformities!Red lines are seismic unconformities recognized by onlap,
downlap, erosional truncation, and toplap!
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Seismic profiles image unconformities!Red lines are seismic unconformities recognized by onlap,
downlap, erosional truncation, and toplap!
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Sequence boundaries = sea-level falls!
Sequence boundaries subdivide onshore record!14 Miocene, 8 Oligocene, 12 Eocene, 7 Paleocene 15-17 Late K!!
Offshore prograding Miocene sequences!
Expedition 313! M27 M28 M29!
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Onshore: Predictable facies!
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Characteristics!• erosional boundaries!• shoaling upwards,
paleodepth from litho- and biofacies!
• each ends near shore!• ages Sr-isotopic dating &
biostrat. ±0.3-0.5 Ma !• ~1.5 Ma duration!
Lower Miocene example!onshore sequences, !
Leg 150X Cape May, NJ!!
Onshore !sequences!
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T1T0 T3 T4 T5T2
R1
TheoreticalThermal
Subsidence<-
Dept
h
T0
T3
T4
T5
T1
T2
T0
T1
ObservedSedimentThickness
DecompactedSediment
Thickness, S*
T0
T1
FirstReduction
R1
T0
T1
equivalentbasin forsedimentthickness S*
paleo-waterdepth
T2 T2 T2
T0
T3
T1
T2
T3 T3
MeasuredSection
R1 =T.S.
ΔSL ρa -ρ
w+ a
ρ
ρa s*aρw
-S* - =ρρ
+ WD
T1T0 T3 T4 T5T2
Sea Level Change & Non-Thermal TectonicsHe
ight
->
ρa -ρ
wR2 = R1 - T.S. ΔSLρa
=
Backstripping Method for Determining Sea-Level
Backstripping: remove compaction, loading, thermal!
Slide from M. Kominz!
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Benthic foraminifers:!Neritic zone!
Inner: 0-30 m ± 15!Middle: 30-100 m ± 30!Outer: 100-200 m ± 50!
Better relative error!
Paleowater Depth: Largest Error Source!Lithofacies:!
Excellent for shoreface to 20-30 m ± 5-10 m error !
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Backstripping provides eustatic estimate!
Backstripping onshore NJ!!
1-D backstripping accounts for!• compaction !• loading (Airy)!• thermal subsidence fit !McKenzie stretching !exponential curve!
!
2-D (Oligocene) accounts for !flexural loading !
!
Residual R2 eustatic estimate & non-thermal subsidence!
ρa - ρw
T.S. = Φ ρa ρs*ρ
a ρw
-ΔSL
ρwρa - ρw
+ WD - ΔSLS* - -
BACKSTRIPPING EQUATIONS
Φ = the basement response function to loadingS* = the decompacted sediment thicknessρ = densitya = asthenospherew = water∆SL = change in eustatic (global) sea-levelWD = paleo-water depth of the sediments
T.S. = tectonic subsidence, or the subsidence of the basin floor in water without any sediment load.
R1 = T.S. ρa ρs*ρ
a ρw
-ΔSL
ρρa - ρw
S* -+ a = + WD
R2 = R1 - T.S. ΔSLρa
=
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Backstripped sea level New Jersey onshore R2!
Kominz et al. (2008) update of Miller et al. (2005)!!Thick black = best estimate,!Thin black = lowstand guestimates !Orange = error!!!Download data !!http://geology.rutgers.edu/people/faculty/19-people/faculty/242-kenneth-g-miller!
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• late Pliocene-Recent: Antarctic and large, variable Northern Hemisphere ice 30-120 m sea-level!
!• Oligocene-early Pliocene:
large, variable Antarctic ice ! 30-60 m sea-level changes!!• Late Cretaceous-Eocene:
Ephemeral Antarctic ice 15-30 m sea-level changes!
δ18O and sea level 105-106 yr scale!
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Large (>25 m), rapid (<1 Myr) sea-level changes only explained by glacioeustasy, yet high latitudes were warm!
Cretaceous-Eocene: An ice-free greenhouse? !
Left: An Ice-Free World: !Shoreline assuming 64 m higher sea level!
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~15 Ma = modern, permanent EAIS!
Greenhouse ice sheets restricted to Antarctic interior !
Antarctic Ice Sheet!
~70 Ma, largest Cretaceous, 40 m!
~33 Ma, e. Oligocene, 55-80 m!
~92 & 96 Ma, big Cretaceous, 25 m!
~93 Ma, typical Cretaceous, 15 m!
Maps: models of Deconto & Pollard (2002) Sea-level: Miller et al. (2011)!
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The Icehouse Cometh:!Heartbeat of the Greenhouse-Icehouse transition!
Animation courtesy of D. Pollard after DeConto and Pollard (2002)!!Beginning illustrates Greenhouse ice growth and decay (~3x CO2)!!End illustrates Oligocene Icehouse (<2.8 CO2 )!
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!
Timing falls ± correct!!
Long-term 100 vs. 250 m!!
Myr-scale amplitudes 30-80 m, not 100+ m!!
Sahagian Russian platform backstripping overlaps & extends to Early Jurassic!!!
�It has been said that ours is the worst form of [sea-level curves] except all the others that have been tried.” Churchill, 1947
Comparison with Exxon estimates!
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• NJ sat high in Cretaceous due to subducting Farallon plate (Müller et al., Science, 2008; Moucha et al., EPSL, 2008; Spasojevic et a., GRL, 2008; Rowley et al., 2013)
• estimate of 150 ± 50 m for Late Cretaceous peak
No such thing as a stable continent!
Kominz et al. (2008)!
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Continental flooding & backstripped estimates !Late Cretaceous estimates!
NJ: 50-70 m (now 100 m)!Exxon: 250 m!Müller (2008): 175 m!Kominz Ridge: 45-365 m (230 m)!Scotian backstrip: 120 m !Continental flooding:!!Harrison (1990): 150 m!
Bond (1979): ~140 m (80-200 m) !QED: 150 ± 50 !Consistent with small changes!!in spreading rates!
Müller !
Miller et al. (2011)!!
Posted at http://geology.rutgers.edu/miller.shtml!
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Scale δ18O to sea-level!Late Miocene ice volume
similar to today, δ18O 0.5‰ lower due to 2°C cooling!
0.1 ‰/10 m calibration!Miller et al. (2011) update using
Lisiecki & Raymo (2005) stack and 67:33 ice:temperature attribution !
δ18O and sea level 105-106 yr scale!
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Deep-sea Mg/Ca paleotemperatures Mg/Ca δ18O + = Paleotemperature + δ18Osw
Cramer et al. (2011) smoothed > 2 Myr! δ18Osw / 0.1‰/10 m = water volume change in meters ~ eustasy!
Cramer et al. (2011)
Miller et al. (in prep.)!
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Deep sea benthic foraminiferal δ18O records All astronomically tuned Cibicidoides records!
Pacific !Sites 574!
Pisias et al., 1985 ! 7 kyr rez!
!
Indian Site 751 this study 10 kyr rez
Atlantic Site 929
Pälike et al.,2006 4 kyr rez
Pacific Site 1218
Lear et al., 2004 40 kyr rez
Different scales reflect different bottom water temperatures, δ18sw Miller et al. (in prep.)!
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Deep sea temperature estimates
δ18Obenthic normalized to Pacific values ~Pacific temperatures Temperature subtracted from δ18Obenthic -0.25‰/°C (Shackleton)
δ18Oseawater converted to sea level 0.1‰/10 m (Fairbanks and Matthews, 1977; deConto and Pollard, 2002; Pekar et al., 2002)
Miller et al. (in prep.)!
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A deep sea δ18O/Mg-Ca based eustatic estimate
No tectonoeustatic correction
This scale may shift Miller et al. (in prep.)!
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Deep sea versus NJ onshore eustatic estimate
Miller et al. (in prep.)!
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No such thing as a stable continent
Moucha et al. (2008)
on
off
200 m change since 30
Ma Onshore
50 m different
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IODP Ex. 313: NJ/Mid-Atlantic Transect!
Summer 2009!
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Offshore Expedition 313: Example from Site 28
Miller et al. (2013a) Geosphere
Age control:!(Browning et al., 2013)!nannofossils!diatoms (Barron et al.)!dinocysts (McCarthy et al.)!Sr-isotopes (Browning et al.)!
Paleodepth: !benthic foraminifera! (Katz et al., 2013) + lithofacies! (Miller et al., 2013b)!!
!
mud
m-c sand
v-f
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Onshore vs. offshore R2 offset: Moucha is right!
R2 = eustasy + non-thermal
tectonism
Offsets between R2 onshore and
offshore indicates non-
thermal tectonism
Onshore
Miller et al. (in prep.)!
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Dynamic topo: modern view of arches, epeirogeny
Rowley et al. (2012)!!
Explains Yorktown problem!Pliocene marine in VA!
Upland gravels NJ !
-20
-15
-10
-5
0
5
10
15
20
25
2468101214 0
high sea levelrelative subsidence
Age, Ma
Langeley, VA
NJ hiatus
NJ eustatic estimate
Exmore, VA
low sea levelrelative uplift
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Site 1308 N. Atlantic!
Integration of atoll, margin, deep-sea records!Pliocene ca. 3 Ma peak sea level 22±10 m CO2 ~400 ppm, !
global T = 1-2°C warmer (Miller et al., Geology, 2012)!
Eyreville, VA!
Enewetak Atoll!
Wanganui Basin!New Zealand!
�likely� (68%) peak sea-levels 17-27 m higher than modern �extremely likely� (95%)� was 12-32 m higher !
Purple: averages ±1 σ of ! Virginia (red points)! New Zealand (black line)! Enewetak (green points)! Mg-Ca δ18O!
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Barbados Acropora palmata (fossil sunshine) !
!120 m ± 5 m lowstand!Last Glacial Maximum!Fairbanks, 1989, 1990)!
!MWP1A rate >40 m/1000 yr!
!(rates from Fairbanks, 1990; Stanford et al., 2006; Miller et
al., 2009; Dechamps et al., 2012; Abdul et al., submitted)!
Barbados ~ global average sea level !D
epth
(m)
Age (ka)
Δδ Ο
(‰)
18
Th/U Age
C Age14
120
110
100
90
80
70
60
50
40
30
20
10
0
1.1
1.0
0.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
1.2
161514131211109876543210 17 18 19 20
Younger DryasChronozone
after Fairbanks (1990)
last glaciation 120 m
7-5 ka, 2 mm/yr
Meltwater pulse 1B 36 mm/yr
Meltwater pulse 1A >40 mm/yr
11-7ka, 8 mm/yr
5-2 ka, 1 mm/yr; 0.75±0.25 mm/yr
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!1st millenium 0 rise; Medieval Warm 2.3 inches/century (0.6 mm/yr); !
Little Ice Age ~0 rise; 20th century 7 inches/century (1.7 mm/yr)!!
!
Kemp et al. (2011)
Little ice age Roman
Warm Period
0.65
-0.65
Sea
leve
l fee
t
Is modern sea-level rise part of a natural cycle?
Medieval Warm Period
Department of Earth and Planetary Sciences
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Global sea level is rising and accelerating Tide Gauges 1880-2006
6.7 inches per century 1.7 ± 0.4 mm/yr
Church & White (2006)
Satellite data 1993-2013 12 inches per century 3.2 ± 0.4 mm/yr http://sealevel.colorado.edu/
Department of Earth and Planetary Sciences
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Why Is global sea level is rising today?
Thermal Expansion: Ocean has gained heat Warmer water is less dense
Global temperature increase explains about 1/3 modern rise
Melting Glaciers & Ice Caps Melting land ice raises sea
level, but not sea ice
Alpine
http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/
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Why Is global sea level Is rising today?
.
~ 30% rise is due to melting mountain glaciers Prior to 2003, < 15% sea level rise was from
melting ice sheets, now greater (Cazenave & Le Cozanne, 2014)
How much sea level is stored in ice sheets? Greenland ~23 ft (7 m) W. Antarctica ~16 ft (5 m) E. Antarctica 170 ft (52 m)
Mountain glaciers
Change of surface elevation Pritchard et al. (2009)
IPCC (2001)
Length
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Revised mass loss figures from ice sheets Mass loss from Greenland and West Antarctica appears to be accelerating
Shepherd et al. (2012)
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National Research Council projections 2012
Scenario-based projections of global sea-level rise by 2100 of 2.7 ft (range 1.7-4.6 feet)
Department of Earth and Planetary Sciences
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Global versus Regional Effects 12 inches/century = 3 mm/yr
global global
16 inches/century = 4 mm/yr
Mid-Atlantic tide gauges; blue = data, green = smoothed fit. Kopp (2013) & Miller et al. (2013)
Global average tide gauges (pink) 6.7 inches/century (1.7 mm/yr) Church & White (2006)
global
Department of Earth and Planetary Sciences
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http://www.dreamstime.com/royalty-free-stock-photos-3d-people-seesaw-image15520048
GIA: Glacial Isostatic Adjustment Melting of ice sheets results in a regional adjustment:
sinking (blue) in some areas, uplift (red) in others
Department of Earth and Planetary Sciences
Ice sheet us
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Fall (red) line separates bedrock & coastal plain
Bedrock sites NYC/Bayonne, Phil./Camden, Baltimore, D.C.
12 inches/century (3 mm/yr) = global + GIA regional
Coastal plain sites Sandy Hook–Norfolk 16-18 in./century (4.0-4.5 mm/yr) = global + regional + compaction
Regional vs. local sea level from tide gauges
Department of Earth and Planetary Sciences
~3 ~3.5 ~4 ~4.5
mm/yr
Miller et al. (2013c)
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Future sea-level rise mid-Atlantic US
Department of Earth and Planetary Sciences
Miller et al. (2013)
Shore = Atlantic City, Cape May 43 cm by 2050, 103 cm by 2100 Bedrock = NYC, Phil., Baltimore, D.C.: 38 cm by 2050, 93 cm ft by 2100
Miller et al. (2013c)
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Future sea-level rise mid-Atlantic US
Department of Earth and Planetary Sciences
Miller et al. (2013)
Shore = Atlantic City, Cape May 43 cm by 2050, 103 cm by 2100 Bedrock = NYC, Phil., Baltimore, D.C.: 38 cm by 2050, 93 cm ft by 2100
Miller et al. (2013c)
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Future sea-level rise mid-Atlantic US
Department of Earth and Planetary Sciences
Miller et al. (2013c) Shore = Atlantic City, Cape May 43 cm by 2050, 103 cm by 2100
Bedrock = NYC, Phil., Baltimore, D.C.: 38 cm by 2050, 93 cm ft by 2100
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Effects of sea-level rise: Coastal flooding By 2100, a “5 to 10-yr storm” will have the flooding of a modern
“100-yr storm”
My house Dec. 1992 nor’easter
My block Sandy 4 PM
Typical nor’easter Nov. 8, 2012
Department of Earth and Planetary Sciences
Miller et al. (2013)
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• Late Cretaceous-Eocene (100-33 Ma): Ephemeral Antarctic ice sheets ~15-30 m sea-level changes!
• Oligocene-early Pliocene (33-2.7 Ma): Large, variable Antarctic ice sheets 30-60 m sea-level changes!
• Late Pliocene-Recent (2.5-0 Ma): Antarctic & Northern Hemisphere ice ages 30-120 m sea-level changes!
!
105-106 yr scale!
104 yr scale!• Globally rising 5-2 ka, 0.75±0.25 mm/yr!• Stable in the Common Era, last 2000 yr!• 20th century, 1.7 mm/y!• Today, 3.2 mm/yr, largely anthropogenic!
Conclusions!
• Long-term sea level 150 ± 50 m 100-60 Ma!107 yr scale!
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Should I sell my shore house?!
Don�t sell: insure!!global >80 cm (2.4 ft) by 2100!NJ >-100 cm (>3 ft)!!
!!
View of NY harbor in an ice-free world (65 m rise)!
More beach erosion, rollback!More cost to replenish!Loss of marshland!Increased storm intensity?!What about those coming behind?!
Vanuatu!
Carteret Is.!
Tuvalu !
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