Sea Level Rise

Magdalena AnguelovaMagdalena AnguelovaPh.D. Student Advisor: Ph.D. Student Advisor: Prof. Ferris WebsterProf. Ferris Webster

Sea Level Rise

Sea Level Rise

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Is Sea Level Rising?

Yes, the sea level is rising.

Sea level has risen about 4 to 8 inches (10 to 20 cm) over the past century.

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Rate of Rising

Sea level will continue to rise.

The important question is:

Will global warming

increase the rate of sea-level rise?

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Impact

Sea level rising will impact coastal areas:

» Coastline retreat;» Inundation of cities,

ports, and wetlands;» Beach erosion ;» Saltwater intrusion into

coastal freshwaters. Cape Henlopen Lighthouse, Lewes, fell in the sea in 1926

due to longterm shoreline retreat.

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» Several mm/yr fall in parts of Alaska.

Sea Level Along the U. S. Coast

Along most of the U. S. coast, sea level has been rising 2.5-3 mm/yr.

» About 1 cm/yr rise on the Louisiana Coast;

The rate varies:

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Factors Affecting Sea Level Rise

Postglacial rebound;

Global warming effects:Heat expansion of the ocean;Melting of mountain glaciers; Melting of Greenland and Antarctic ice

sheets.

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The Effects of Glacial Period

An enormous volume of water was removed from the oceans and was locked in ice sheets on the land.

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Glaciation Effects: Ice advancement

As the ice sheet advanced on the land...

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... the shoreline moved seaward.

Glaciation Effects: Displaced Shoreline

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Glaciation Effect: Ice Compression

The ice weight compressed the land downward.

And ...

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Glaciation Effect: Low Sea Level

... the sea level dropped about 130 m. Bangor,

Maine, is an example.

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Postglacial Rebound: Initial Flooding As the ice melted during the

deglaciation, sea level rose rapidly.

Bangor was flooded.

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Postglacial Rebound: Land Uplift

The land, unloaded from the massive ice sheets, started to uplift slowly.

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Postglacial Rebound

When the rate of land uplift exceeded the rate of sea-level rise due to ice melting, the seas retreated from the Bangor region

again.

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Postglacial Rebound

Since deglaciation, the Nordic countries have undergone an uplift of up to 250 m.

Postglacial rebound continues in Northern Europe.

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Global Warming Effects: Heat Expansion of the Ocean

With global warming, the temperature of the ocean would increase;

Like many other substances, seawater expands when heated.

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Global Warming Effects: Melting of Polar Ice

Ice at the North Pole is floating on the ocean and melting there due to global warming would not affect sea level.

Arctic Iceberg in Spring. Alaska, USA

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Global Warming Effects: Ice Sheets and Glaciers

Mountain glaciers and ice in Greenland and Antarctic are, thus, a cause for concern.

However, melting of ice resting on land would add to sea level.

Crowfoot GlacierBanff National Park, Alberta, Canada

Ice sheet in Antarctica

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Global Warming Effects: Mountain Glaciers

Mountain glaciers have been shrinking for the past century;

Glaciers on Mont Blanc Haute-Savoie, France

The water released into streams and rivers is being added to the sea.

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To Summarize…

The current sea level rise is due to:

» Thermal expansion -- about 5 cm (2”);

» Melting of small glaciers

and the ice edges of Greenland and Antarctica -- another 5 cm.

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Possible Sea Level Fall Antarctic ice may accumulate and lower sea level.

Global warming might melt the ice at the edges of Antarctica.

But warm air will carry more moisture, which will then precipitate as snow in the interior of Antarctica.

Snow petrels resting on a large iceberg near Adelaide island, Antarctic.

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What to Expect?

About 70 cm!

A possible rise over the next century is

from:» Small glaciers melting -- about 40 cm;» Thermal expansion -- about 30 cm.

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