sea leve rise: an overview

Sea Level Rise & Bay Area Predictions: A

Comprehensive Review

A Senior Project by Lee Jasperse, SVHS Senior

Why should you care?

•More than 600 million people live in low-lying coastal zones worldwide.

•1 meter sea level rise would inundate the San Joaquin Delta, areas of Napa, Palo Alta, Alameda, & San Francisco.

•Most newly vulnerable areas are developed areas.

What will be discussed?•Eustatic vs. Local sea level rise

•Eustatic sea level rise

•Contributions to global mean sea level rise

•Global mean sea level rise projections

•Bay Area sea level rise

•Contributions to localized flooding

•Flooding predictions in the Bay Area

• Implications

•Next Steps

What’s the difference?

Eustatic SLR: Eustatic SLR: the global mean sea level rise.the global mean sea level rise.

Caused by temperature changes, melting Caused by temperature changes, melting glaciers, etc. glaciers, etc.

195 mm from 1870 - 2000195 mm from 1870 - 2000

Local SLR: Localized, often short term, Localized, often short term, increases in water levels.increases in water levels.

Caused by tides, storm conditions, El Nino, floods, etc.

Roadmap•Eustatic vs. Local sea level rise







• Implications

•Next Steps

Global Sea Level Rise

SLR acceleration

of .013 ± .0006 mm

yr-2








• Implications

•Next Steps

Contributing Global Factors

Thermal Expansion Thermal Expansion

Ice LossIce Loss

Glaciers & Ice CapsGlaciers & Ice Caps

GreenlandGreenland

AntarcticaAntarctica


Thermal ExpansionThermal Expansion

Ice LossIce Loss


GreenlandGreenland


Left: Est. contributions to SLR from 1993-2003 (IPCC). Above:

Est. contributions to SLR from 1996-2006 (Meier et al. 2007).

Thermal Expansion•Water expands as it’s heated.

•Contributed ~25% of SLR from 1955-1995

•Contributed ~50% of SLR from 1993-2003

•Projected to contribute more than 50% to SLR between 2008 and 2100.

•IPCC TAR estimates 1990-2100 contribution to be 110 - 430 mm.



Ice LossIce Loss


GreenlandGreenland


Contributions from ice loss

Present day contributions

From Meier et al. (2007) & Monga Bay

Future contributions from ice loss

Total contributions from present to 2100

From Meier et al. (2007)



Ice LossIce Loss


GreenlandGreenland


Glaciers & Ice CapsGlaciers & Ice CapsHistoric contributionHistoric contribution

1961-2003: 0.5 ± 0.18 mm / year1961-2003: 0.5 ± 0.18 mm / year

1993-2003: .77 ± 0.22 mm/year1993-2003: .77 ± 0.22 mm/year

20% of observed rise by 199820% of observed rise by 1998

Future ContributionFuture Contribution

Present - 2100: 240 ± 128 mmPresent - 2100: 240 ± 128 mm

Only 35% of volume will be depleted by Only 35% of volume will be depleted by 2100.2100.



Ice LossIce Loss


GreenlandGreenland


Greenland

Potential SLR contribution: 7.2 metersPotential SLR contribution: 7.2 meters

Historic contributionHistoric contribution

1993-2003: 0.2 ± 0.1 mm / year1993-2003: 0.2 ± 0.1 mm / year

Future ContributionFuture Contribution

Present - 2100: 240 ±128 mmPresent - 2100: 240 ±128 mm

Possibly double or triple current estimates Possibly double or triple current estimates (Csatho 2008, Carlson et al. 2008).(Csatho 2008, Carlson et al. 2008).



Ice LossIce Loss


GreenlandGreenland


Antarctica

Historic contribution

1993-2003: 0.2 mm / year

Future Contribution

West Antarctic Ice Sheet: 120 ± 50 mm

East Antarctic Ice Sheet: -56 ± 40 mm








• Implications

•Next Steps

IPCC Prediction

•Depending on the greenhouse gas emissions scenario, SLR could range from .18 to .59 meters.

•Estimates are considered very conservative.

•Does not include contributions from ice sheet flow.

Examining the paleoclimate

• Models underestimate contributions from the Greenland & Antarctic Ice Sheets.

• Examine historical sea level rise and deglaciation.

• Overpeck: 1+ meter of SLR by 2100, and committed to 4-6 meters over the next few hundred years.

Carlson et al & Overpeck et al

A simpler method...

•Computer modelling has underestimated observed SLR.

•“Semi-Empirical Approach”: Correlates long term SLR with global temperature.

•Closely matches observed SLR.

•Grinsted: .7 - 1.1 meters of SLR for B1 emission scenario. 1.1 - 1.6 meters for the A1F1 scenario.

Rahmstorf & Grinsted

Uncertainty•Low Uncertainty:

•Thermal Expansion

•High Uncertainty:

Greenland & Antarctica

Ice sheet flow & ice dynamics

Sea levels act as positive feedback, destabalizing ice sheets

Increased # of suraglacial lakes

Environmental Impacts

•A collapse of the Western Antarctic Ice Sheet would shift Earth’s rotational axis 500 meters, shifting water globally towards North Americ and the southern Indian Ocean.

•Arctic animals may go extinct (seals, polar bears).

• Salt water intrusion in coastal habitats and aquifers.

•Marshes and wetlands will be inundated.

• 14,000 sq. miles would be inundated in the US.

Social Impacts

•Coastal and island populations will be displaced.

•634 million people live in low-elevation coastal zones.

•Island nations may be entirely submerged.

•Kiribati

Economic Impacts

•$1,182 billion (1995 US dollars) will be lost solely from global wetland loss.

•Global warming may result in a 20% cut in global GDP.

Sea Level Rise in the Sea Level Rise in the Bay AreaBay Area

Oakland Airport








• Implications

•Next Steps

Contributing Factors

Mean SLR (follows global trend)Mean SLR (follows global trend)

Water level factorsWater level factors

Spring tidesSpring tides

Storm SurgeStorm Surge

Barometric effect: -1 atm = +1 inch SLRBarometric effect: -1 atm = +1 inch SLR

El NinoEl Nino







El NinoEl Nino

Erosion/Deposition dynamicsErosion/Deposition dynamics

Tides• Vary around mean sea level on a daily time scale.

Tides• Also vary around a monthly timescale.

Tides•Tides are highest during spring tides — tides that rise the highest and fall the lowest.

Tides•Tides are the largest component of sea level change, and are the most predictable.






Barometric effectBarometric effect

El NinoEl Nino


Storm Surge & Barometric Effect•Combination of persisent winds and low pressure.

•Strong surface winds causes water levels to increase at the downward shore. Wind whips can cause stronger waves with greater momentum.

•Low atmospheric pressure increases sea level (-1 atm = +1 inch).

•In the SF Bay, maximum effect is 1 meter SLR.

•Impact rarely exceeds .3 m.

•“Wave induced surge on a beach... can reach 1.5 m.” (Cayan et al)







El NinoEl Nino


El Nino•Sustained sea surface temperature anomalies >5ºC

•Leads to storm conditions and abnormally high tides.

•Ex: El Nino caused tides in San Francisco to be ~2 feet higher than normal in the early winter months of 1997 & 1998.

•Local thermal expansion







El NinoEl Nino


Erosion/Deposition Dynamics•Sediment from

erosion builds up.

•Changes spatial component of land.








• Implications

•Next Steps

Predictions•Likely 1.4 m mean SLR in the Bay Area.

•Flooding occurs when sea level extremes occur — spring tides, low atmospheric pressure & storm events, and El Nino occur simultaneously.

•San Francisco Bay appears sensative to sea level changes — the occurrence of extremes has increased 20-fold since 1915.

Predictions•As mean sea level rises & severe weather conditions potentially become more severe, the risk of large scale flooding increases.

•Projected monthly SF sea level anomolies from the mean sea level.From Cayan et al.

(2007)

Predictions

•The amount of land vulnerable to flooding increases significantly.

•Most newly vulnerable land are the Central and South Bay’s developed areas.

Uncertainty•Mean global sea level.

•Sediment erosion, supply, and deposition.

•Levee failure.

•Frequency of storm surge / El Nino events.








• Implications

•Next Steps

Implications

Environmental Impacts

•Wetlands and grasslands are among those at greatest risk of flooding.

•Saltwater will flow into the Sacramento-San Joaquin River Delta, from which fresh water is pumped to about 67% of Californians. It will also intrude on aquifers.

•22 industrial and municipal wastewater systems are at risk of inundation.

•Shoreline dumps and military installations threatened by a rising bay could leak biological and chemical contaminents into the bay.

Impacts in terms of land cover

From Noah Knowles, USGS

Image from Noah Knowles, USGS

Social Impacts•Those who live in parts of Corte

Madera, San Rafael, Hayward, Newark, Marin (Sausalito), San Francisco, and the Silicon Valley shoreline would likely be displaced.

•480,000 people at risk from SLR along California coast.

9600 people vulnerable in Sonoma County with a 1.4 m mean SLR.

Disproportionately high impact on low income families in Sonoma.

Economic Impacts•High cost due to wetland loss ($6-$30

thousand per acre lost).

•Substantial damage to infrastructure:

25.9 miles of vulnerable roads and highways in Sonoma County

San Francisco and Oakland airports

•Cost of flooding of buildings & houses along California coast estimated at $100 billion.

$.48 billion in Sonoma County.

•San Francisco and Oakland airports








• Implications

•Next Steps

Next Steps•Study in greater detail SLR’s spatial

impact.

•Prepare for sea level rise:

•Revamp levies & walls ($14 billion California-wide investment)

•Perform a cost/benefit analysis to determine which areas to protect most heavily.

•Restore buffers.

Thank You!

sea leve rise: an overview

Education

meter sea level rise

historical sea level

ice loss total contributions

eustatic slr

global temperature

future contributions

local slr

greenland antarctic