Impact of Sea Level Changes on Barrier Islands We’re all going to die!

Impact of Sea Level Changes on Barrier Islands

We’re all going to die!

The Myth of Sea Level Rise and Global The Myth of Sea Level Rise and Global WarmingWarming

““Even if the polar ice caps melted, there would be no rise in ocean Even if the polar ice caps melted, there would be no rise in ocean levels... After all, if you have a glass of water with ice cubes in it, as levels... After all, if you have a glass of water with ice cubes in it, as the ice melts, it simply turns to liquid and the water level in the glass the ice melts, it simply turns to liquid and the water level in the glass remains the same."remains the same."

Excellent theory...... The only problem is Antarctica is a Excellent theory...... The only problem is Antarctica is a CONTINENT with large quantities of ice on top of it. CONTINENT with large quantities of ice on top of it. When the ice melts, new water will enter the ocean.When the ice melts, new water will enter the ocean.

The Reality of Sea Level Rise and Global The Reality of Sea Level Rise and Global WarmingWarming

The History of Sea Level RiseThe History of Sea Level Rise

• Throughout history, sea level is constantly Throughout history, sea level is constantly rising and falling because of the glacial and rising and falling because of the glacial and interglacial periodsinterglacial periods

• Currently we are in a state of sea level rise Currently we are in a state of sea level rise

History cont’d...History cont’d...

• Major changes in Quaternary periodMajor changes in Quaternary period

• In the past 20,000 the sea level has oscillated 130mIn the past 20,000 the sea level has oscillated 130m

• Since human occupation of coasts, sea level has Since human occupation of coasts, sea level has risen less than 3 mrisen less than 3 m

RecentlyRecently

• Recently on the coasts we are seeing a general Recently on the coasts we are seeing a general rise in sea level of 3-4mm/yrrise in sea level of 3-4mm/yr

• Mississippi delta region is seeing a 9mm/yr Mississippi delta region is seeing a 9mm/yr rise resulting in 40 acres land lost/monthrise resulting in 40 acres land lost/month

Sea level is never a constant over space and timeSea level is never a constant over space and time

Variations in sea level may be local or regional:Variations in sea level may be local or regional:

1) Atmospheric pressure and winds1) Atmospheric pressure and winds

2) Freshwater discharge from rivers2) Freshwater discharge from rivers

3) Ocean Currents3) Ocean Currents

4) Geophysical conditions4) Geophysical conditions

The Pacific Ocean is approximately 1 meter higher than the The Pacific Ocean is approximately 1 meter higher than the Atlantic OceanAtlantic Ocean

Sea level rise is also never consistent Sea level rise is also never consistent and not accurate because it is and not accurate because it is measured by tide gage data. This measured by tide gage data. This date is not evenly distributed, it is date is not evenly distributed, it is measured near population centers measured near population centers where the data is skewedwhere the data is skewed

Causes for Sea Level RiseCauses for Sea Level Rise

• Tectonic ActivityTectonic Activity

• SubsidenceSubsidence

• IsostacyIsostacy

• EustaticEustatic

Plate TectonicsPlate Tectonics

• Upheaval and subsidence of platesUpheaval and subsidence of plates

• May be local or regional and may be sudden or gradualMay be local or regional and may be sudden or gradual

• Volcanic eruptions and faultingVolcanic eruptions and faulting

SubsidenceSubsidence

Withdraw of fluids from pore space Withdraw of fluids from pore space in the sediment which therefore in the sediment which therefore causes it to collapsecauses it to collapse

SubsidenceSubsidence• Local rise in sea level based of fluid removal and compactionLocal rise in sea level based of fluid removal and compaction

• Construction of oil wells and drainage of aquifersConstruction of oil wells and drainage of aquifers

• Construction of high rises and discharge of sediment loads in Construction of high rises and discharge of sediment loads in the Mississippi Valley Delta (ie. New Orleans)the Mississippi Valley Delta (ie. New Orleans)

• 6-7 mm of the 9-10mm/yr rise in Mississippi delta is dues to 6-7 mm of the 9-10mm/yr rise in Mississippi delta is dues to subsidencesubsidence

IsostacyIsostacy

Equilibrium condition of the Equilibrium condition of the earth’s crust due to balancingearth’s crust due to balancing

In other words...In other words...

• Looking at the earth’s surface and the forces on itLooking at the earth’s surface and the forces on it

• Some forces want to push up (elevate the Some forces want to push up (elevate the lithosphere) while some want to push down (depress lithosphere) while some want to push down (depress the lithosphere)the lithosphere)

IsostacyIsostacy

• Volume of water remains the same, land Volume of water remains the same, land rises or falls because of weight of ice sheetrises or falls because of weight of ice sheet

• Glacial compaction and rebound - Glacial compaction and rebound - Weight of glaciers on plates depress the Weight of glaciers on plates depress the the lithosphere 100’s m forming a the lithosphere 100’s m forming a peripheral bulgeperipheral bulge

• Subsequent melting of glaciers cause the land to Subsequent melting of glaciers cause the land to reboundrebound

• Causes bulge to move back to original shapeCauses bulge to move back to original shape

Isostacy cont’dIsostacy cont’d

1)1)

2)2)

3)3)

4)4)

EustaticEustatic

Global change in sea level based on Global change in sea level based on changes of the volume/density of water. changes of the volume/density of water. The relative position of land does not The relative position of land does not changechange

1) Melting of polar ice caps1) Melting of polar ice caps

Eustatic cont’dEustatic cont’d

• Related to the climate and the shape changes in Related to the climate and the shape changes in the holding capacity of the oceans basinsthe holding capacity of the oceans basins

2) Thermal expansion of the oceans 2) Thermal expansion of the oceans (biggest factor)(biggest factor)

With an average water column of With an average water column of 3000 m and a basin that stays the 3000 m and a basin that stays the same, the sea level could rise by 60 same, the sea level could rise by 60 cm for every degree of warmingcm for every degree of warming

What causes thermal expansion?What causes thermal expansion?

• Global warming which is caused by the Global warming which is caused by the introduction of COintroduction of CO22 into the atmosphere into the atmosphere

• Estimates indicate an increase in greenhouse Estimates indicate an increase in greenhouse gases, temperature and sea level rise. Predict gases, temperature and sea level rise. Predict a temperature rise of 1.5C to 4.5C for COa temperature rise of 1.5C to 4.5C for CO22

alone and as much as 3-9C for all gases.alone and as much as 3-9C for all gases.

Why do we care?Why do we care?

•Shoreline RetreatShoreline Retreat

•FloodingFlooding

•Saltwater IntrusionSaltwater Intrusion

Shoreline RetreatShoreline Retreat

For every unit of sea level rise, the high water mark For every unit of sea level rise, the high water mark increases by 1000x that distanceincreases by 1000x that distance

80% of the population of the United States lives within 80% of the population of the United States lives within 100 miles of the coast100 miles of the coast

The Bruun RuleThe Bruun Rule. Beaches follow a characteristic profile shape based on the wave climate . Beaches follow a characteristic profile shape based on the wave climate and the types of sediments. When sea level rises, the initial effect is inundation; but and the types of sediments. When sea level rises, the initial effect is inundation; but eventually enough material will be deposited offshore to re-establish the profile at the eventually enough material will be deposited offshore to re-establish the profile at the higher elevation. Thus, the shore retreat will be based on the slope of the entire beach higher elevation. Thus, the shore retreat will be based on the slope of the entire beach profile, which is usually flatter than the slope just above the shore.profile, which is usually flatter than the slope just above the shore.

FloodingFlooding

1) Because of the effects of sea level rise, a one meter rise in 1) Because of the effects of sea level rise, a one meter rise in sea level will allow 15-year storm to flood areas that would sea level will allow 15-year storm to flood areas that would only previously be flooded by a 100-year stormonly previously be flooded by a 100-year storm

2) Beach erosion would leave coastal infrastruction more 2) Beach erosion would leave coastal infrastruction more vulnerable to storm wavesvulnerable to storm waves

3) Coastal drainage would be reduced, increasing the 3) Coastal drainage would be reduced, increasing the impacts of coastal rainstormsimpacts of coastal rainstorms

4) Finally, a rise in sea level would raise water tables4) Finally, a rise in sea level would raise water tables

Saltwater IntrusionSaltwater Intrusion

1) Increased sea level would allow further penetration of 1) Increased sea level would allow further penetration of saltwater up rivers, bays, estuaries and aquiferssaltwater up rivers, bays, estuaries and aquifers

2) This would harm plants and animals not adapted to salt 2) This would harm plants and animals not adapted to salt or brackish watersor brackish waters

3) Contamination of aquifers would threaten human uses of 3) Contamination of aquifers would threaten human uses of potable waterspotable waters

Possible Impacts of Sea Level Rise for the Possible Impacts of Sea Level Rise for the Atlantic CoastAtlantic Coast

Responses to Sea Level RiseResponses to Sea Level Rise

1) Protection by hard structures and coastal 1) Protection by hard structures and coastal armoringarmoring

2) Strategic Retreat2) Strategic Retreat

3) Beach Renourishment3) Beach Renourishment

4) Elevating Roads and Structures4) Elevating Roads and Structures

Bulkheads and LeveesBulkheads and LeveesExpensive process that can cost between $130-$500 per linear Expensive process that can cost between $130-$500 per linear footfoot

Wave action into bulkhead projects energy downward, Wave action into bulkhead projects energy downward, actually increasing erosion seaward of the bulkheadactually increasing erosion seaward of the bulkhead

Bulkhead and other hard structures are illegal in some statesBulkhead and other hard structures are illegal in some states

Sea Bright, New JerseySea Bright, New Jersey

Strategic RetreatStrategic Retreat

Relocation of property away from eroding beachRelocation of property away from eroding beach

Paul Foster’s house on Figure 8 island, approximately $25,000 Paul Foster’s house on Figure 8 island, approximately $25,000 to relocate a house.to relocate a house.

Price may seem high, but it protects investments of millions of Price may seem high, but it protects investments of millions of dollarsdollars

Not all houses can be movedNot all houses can be moved

Amount of relocation space is finite, erosion may still destroy Amount of relocation space is finite, erosion may still destroy the housethe house

Beach RenourishmentBeach Renourishment

Relocation and addition of beach quality sand from source Relocation and addition of beach quality sand from source destination to eroding beachdestination to eroding beach

Beach renourishment projects have the potential to be very Beach renourishment projects have the potential to be very costly (~$3-$4 a cubic yard)costly (~$3-$4 a cubic yard)

Beach renourishment is not permanent and will require Beach renourishment is not permanent and will require additional renourishment within a couple of yearsadditional renourishment within a couple of years.

BeforeBefore

AfterAfter

Elevation of Roads and HousesElevation of Roads and Houses

Extremely expensive alternative that will not stop the rise of Extremely expensive alternative that will not stop the rise of sea level.sea level.

Was used in Galveston, TX at the turn of the century, as a Was used in Galveston, TX at the turn of the century, as a response to hurricane flood damage.response to hurricane flood damage.

Estimated Cost of Coastal Protection in the United States

270-475 billion dollars

Remember......Remember......

We’re all going to die!

http://www.epa.gov/globalwarming/publications/impacts/sealevel/barrier_islands.html

http://www.erols.com/jtitus/Holding/NRJ.html

http://www.nap.edu/books/0309037816/html/40.html

http://www.greenpeace.org/~climate/arctic99//reports/seachange.html

http://www.uncwil.edu/people/hosier/CMGMT/SeaLevel.htm

http://www.edf.org/programs/GRAP/hotny/

Rising Seas, Coastal Erosion, and the Takings Clause: How to Save Wetlands and Beaches Without Hurting Property Owners– Maryland Law Review, Volume 57, 1279-1399 (1998).

The Risk of Sea Level Rise: A Delphic Monte Carlo Analysis in which Twenty Researchers Specify Subjective Probability Distributions for Model Coefficients within their Respective Areas of Expertise

– Climatic Change, 33: 151-212 (1996).

The Probability of Sea Level Rise– U.S. Environmental Protection Agency, #EPA 230-R-95-008 (1995).