Environment Sea Level Rise - الصفحات الشخصية | الجامعة ...site.iugaza.edu.ps/mabualtayef/files/04-Chapter-4-Ice...Eustatic changes = volumetric (mass) changes

Coastal & MarineEnvironment

4Chapter

Sea Level Rise

Mazen AbualtayefAssistant Prof., IUG, Palestine


4Chapter

Sea Level Rise is defined as a mean

rise in sea level

What is Sea Level Rise?


4Chapter

What happens to the island?

When sea level rises……

How does the slope of the land influence the loss of shoreline?

Gentle slopeSteeper slope

west east

Island


4Chapter present sea level

Tide gauge

increase due to climate warming

decrease due to climate cooling



Tide gauge

decrease due to land rising

increase due to land subsidence



Tide gauge

What about an area with excessive sediment input, does sea level change?

Sea level remains constant, the container holding the water (oceans) is very large.


4Chapter

• Climate warmingGlacial ice melts and seawater volume expands

• Climate coolingMore glacial ice forms and seawater volume

contracts

• Land rebound (rising)Rebound of land due to former glaciation and

removed

• Land subsidence (sinking)Withdrawal of groundwater or petroleum

Relative Sea Level Change


4Chapter

Global Warming Processes

(Source:http://www.cotf.edu/ete/modules/climate/GCclimate1.html)

(Source:http://library.thinkquest.org/C0051

37F/automobile_traffic_pollution.jpg)

• This process can

lead to an increase in

global temperature

when greenhouse

gases are added to

the atmosphere

• An increase in global

temperature can result

in sea level rise due to

the melting of glaciers

The Greenhouse Effect

is a process that

makes the Earth

inhabitable

(Source: NASA)


4Chapter Ice and snow profoundly affect our

climate. During the Northern Hemisphere

winter, they blanket up to 16% of the Earth’s

surface with a bright covering that reflects

much of the Sun’s radiant energy back to

space. During the Southern Hemisphere

winter, they cover about half this area.

An expected consequence of global warming

is a decrease in the Earth’s snow and ice

cover, which would increase the global

absorption of solar radiation and, in the event

of a significant melting of land ice, increase

sea level.

Background

Iceberg


4Chapter

Ice sheets and glaciers are important

reservoirs for fresh water. Approximately 75%

of the world’s fresh water is stored in ice, the

remainder being stored underground or in

lakes, rivers and streams. Of the 75% in ice,

approximately 91% is held in the Antarctic ice

sheet, 8% in the Greenland ice sheet, and the

remaining 1% in mountain glaciers.

Background


4Chapter

Over the past century, sea level has slowly been

rising. This is in part due to the expansion of

ocean water as it warms and in part due to the

addition of water to the oceans through either the

melting or the calving off of icebergs from the

world’s land ice. A vast majority of individual

mountain glaciers and ice caps are known to have

been retreating, some very rapidly, and their melt

and consequent runoff contribute to sea level rise.

Although scientific evidence is increasing that on

balance, both the Greenland and Antarctic ice

sheets are shrinking, it is still uncertain what

impact this will have on the world’s population. If

all the ice melted or otherwise entered into the

oceans, global sea level would rise by

approximately 70 meters.

Background


4Chapter

Average Rate ~ 1.8 mm/year

0.8 mm/year

2.0 mm/year

Global Mean Sea Level from Tidal Gauge observations around world


4Chapter

100 0.0740.018

50 0.1280.026

Warmest 12 years:1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000

Period Rate

Years /decade

Global mean temperatures


4Chapter

Contribution to Sea Level by

Thermal Expansion

-15

-10

-5

0

5

10

15

20

1960 1970 1980 1990 2000

DM

SL

(m

m)

Year

Rate = 0.4 mm/year (1955-2004)


4Chapter

Contribution to Sea Level by

Mountain Glaciers

0

5

10

15

20

25

1960 1970 1980 1990 2000 2010

DM

SL (

mm

)

Year

1961-2003: 0.5 mm/year

0

5

10

15

20

25

1960 1970 1980 1990 2000 2010

DMS

L (

mm

)

Year


4Chapter

Sea Level Budget (IPCC-2007, mm/year)

Thermal Expansion

Mountain Glaciers

Greenland Ice Melt

Antarctic Ice Melt

Land Water Storage

Total of Observed Contributions

+

+

+

=

Observed Sea Level Change

1.6 ± 0.5

0.8 ± 0.2

0.2 ± 0.1

0.2 ± 0.3

?

2.8 ± 0.7

1993-2003 1961-2003

0.4 ± 0.1

0.5 ± 0.2

0.1 ± 0.1

0.1 ± 0.4

?

1.1 ± 0.5

3.1 ± 0.7 1.8 ± 0.5


4Chapter

1. According to observations and

measurements, average global

increase in sea level is 1-2

mm/year.

2. Mean Sea Level is projected to

rise by 0.18 m to 0.59 m by 2100,

But with Significant Regional

Variations, IPCC 2007)


4Chapter

Factors affecting sea level

Not directly climate related:

• Tides – Periodic changes due to changing orbital motions of earth & moon

• Storm surges - Atmospheric effects

• inverse barometer, tropical storm/hurricane surges

• Wind-stress driven surge

Directly climate related:

• Isostatic – Vertical movement of land

• Eustatic – changes of total sea water mass

• Steric – Thermal expansion of water volume


4Chapter

Factors affecting sea level:

Astronomical tides

0 5 10 15 20 25Time (days)

-2

-1

0

1

2

Sea

leve

l


4Chapter


Atmospheric variations

Inverse barometer effect

The inverse response of sea level to changes in atmospheric pressure.

A static reduction of 1.005 mb in atmospheric pressure will cause a stationary rise of 1 cm in sea level

1000mb

980mb

20cm

Low Atmospheric Pressure


4Chapter


Storm surges

1. A deep centre of low pressure situated over

Scandinavia produces northerly winds.

2. Wind stress forces surface waters into the “bottle-

neck” of the English Channel.

3. Flow is restricted by the Straits of Dover and sea

levels rise along the adjacent coasts of East Anglia

and the Netherlands.

4. Other key ingredients include high Spring tides and

on-shore winds.


4Chapter


Isostatic changes

Isostatic changes = vertical land movements

Examples:

• Stockholm, Sweden (Glacial Isostatic Adjustment).

• Nezugaseki, Japan (abrupt jump in sea level

record following earthquake in 1964).

• Fort Phrachula Bangkok, Thailand (sea level rise

due to increased groundwater extraction since

about 1960).

• Manila, Philippines (recent deposit from river

discharges and reclamation works).

• Honolulu, Hawaii (a site in the PGR 'far field'

without evident strong tectonic signals on

timescales comparable to the length of the tide

gauge record and with secular trend 1.5 mm/year).


4Chapter


Eustatic changes

Eustatic changes = volumetric (mass) changes

Glaciers, ice-caps or ice-sheets:• Gain mass by accumulation of snow (snowfall and

deposition by wind-drift), which is gradually transformed to ice.

• Lose mass (ablation) mainly by melting at the surface or base with subsequent runoff or evaporation of the melt water.

• Net accumulation occurs at higher altitude.• Net ablation at lower altitude.• The mass balance for an individual body of ice is

usually expressed as the rate of change of the equivalent volume of liquid water, in m3/yr; the mass balance is zero for a steady state.


4Chapter


Steric rise• As oceans warm, density decreases and thus even at

constant mass the volume of the ocean increases.

• Thermal expansion (or steric sea level rise) occurs

at all ocean temperatures.

• Water at higher temperature or under greater

pressure (at greater depth) expands more for a given

heat input. Therefore, the global average expansion

is affected by the distribution of heat within the ocean.

• Salinity changes within the ocean also have a

significant impact on the local density and thus local

sea level, but have little effect on global average sea

level change.

• The rate of climate change depends strongly on the

rate at which heat is removed from the ocean surface

layers into the ocean interior – if heat is taken up

more readily, climate change is retarded but sea level

rises more rapidly.


4Chapter

Δh (t) = X (t) + g (t) + G (t) + A (t) + I (t) + p (t) + s (t)

The components of MSL rise are due to:

X is the thermal expansion (steric rise);

g is the loss of mass of glaciers and ice caps (eustatic rise);

G is the loss of mass of the Greenland ice sheet due to current climate change

(eustatic rise);

A is the loss of mass of the Antarctic ice sheet due to current climate change

(eustatic rise);

I is the loss of mass of the Greenland and Antarctic ice sheets due to the ongoing

adjustment to past climate change (eustatic rise);

p is the runoff from thawing of permafrost (eustatic rise);

s is the deposition of sediment on the ocean floor.


4Chapter

Sea-Level Rise Impacts

• Periodic flooding and permanent inundation – “a whole new floodplain”

• Coastal squeeze– Coastal ecosystem migration halted by

engineered shoreline defenses

• Shoreline recession– Inland migration of natural shorelines

• Ecosystem transformation – Shift in aereal extent of coastal habitats

and habitat relationships

• Saltwater intrusion– Inland migration of salt/fresh surface and

groundwater interface


4Chapter

Coastal erosion and accretion

• 1 cm rise in MSL erodes approx 1m horizontally of beach

• Sea level rise has a profound effect on rate of sedimentation

• Varying of sedimentation rates -> changing vegetation zones e.g. growth/shrinkage of marshes

• Storm surges force large quantities of shore-face sediments through inlets -> create tidal deltas/barriers

1m 0.1


4Chapter

Vulnerable populated regions

Large Coastal Cities:Populations >8 million

(over 50% of US population live in coastal areas, >110 million)

Highly populated Delta regions:Vulnerable to MSL rise

http://www.survas.mdx.ac.uk


4Chapter

Flood and storm damage

• Coastal region more susceptible to storm surges, flooding, beach/coastal erosion=> disruption of activities; danger to life; infrastructure damage

• 1 m rise in MSL would enable a 15-year storm to flood areas that today are only flooded by 100-year storms

• Urban flooding: contaminated water supply; drainage/waste systems overwhelmed

• Flood damages would increase 36-58% for a 30-cm rise in sea level, and increase 102-200% for sea level rise greater than 90 cm

Source: National Hurricane Service


4Chapter

Increased salinity in estuaries• Saltwater will penetrate farther inland and

upstream in estuaries i.e. estuarine salt wedge.

• Higher salinity impairs both surface water and human groundwater water supply

• Saltwater intrusion would also harm ecosystems:• aquatic plants and animals e.g. salt marshes,

mangroves• Higher salinity has been found to decrease

seed germination• Flooded agricultural land takes a long time to

recover from saline water

• Decline of coastal commercial fisheries e.g. Salinity intrusion has already been cited as primary reason for reduced oyster harvests in Delaware and Chesapeake Bays in the USA


4Chapter

Potential Impacts on the

Natural Environment

Loss of habitat such as coral reefs

and wetlands may have significant

impacts in the coastal zone


4Chapter

Potential Impacts on Humans

and the Built Environment

(Source: www.jri.org.uk/brief/ climatechange.htm)

As coastal

populations

increase,

vulnerability of

those populations

to sea level rise

increases as well.

7 million people live

below the 1 meter

contour line in

Bangladesh.


4Chapter

Sea-Level Rise Policy

Continuum

Coastal County or Municipal Government


4Chapter

To ensure adequate protection of the

built environment through soft and hard

shoreline stabilization that seeks to

maintain a static shoreline position

within the City.

Protection


4Chapter

Seawall - Kailua-Kona, HI

Motorway Dike - Netherlands Living Shorelines

Hard Stabilization

Living Shorelines

Soft Stabilization


4Chapter

Protection Considerations

Advantages Disadvantages

• Protects important private

and public infrastructure

• Creates investor certainty

• Can be used with other

strategies

• Requires long-term

maintenance

• May be unsustainable

(depending on SLR rates)

• Ecologically problematic

• Loss of sandy beaches,

coastal squeeze


4Chapter

Accommodation

To accommodate increasing sea

levels and the additional flooding

that will result by adapting the built

environment and enhancing the

resiliency of the natural environment

where it is economically and

ecologically practicable to do so.


4Chapter

Floating Bridge - Seattle, WA

Multi-family floating canal houses -

Scheepstimmermanstraat, Amsterdam House on stilts – New Orleans, LA

Floating House – Brad Pitt’s Make

it Right Foundation, New Orleans,

LA

http://www.inhabitat.com/2009/10/06/brad-pitt-unveils-floating-house-for-make-it-right-foundation/float-house/


4Chapter

Accommodation Considerations


• Allows development to

proceed in transition

areas and where SLR is

uncertain – threat of sea

level rise is prolonged

• Minimizes damage

• Increases vulnerability

• Alters the

characteristics of

shorelines

• Short-term solutions that eventually lead to

protection or managed

relocation strategy

Prolonged: مطول

Vulnerability: قابلية اإلصابة


4Chapter

To Reduce vulnerability in the built

environment and preserve coastal

ecosystems through changes in land

use and the orderly abandonment

and /or landward relocation of

structures and associated

infrastructure

Managed Relocation


4Chapter

Managed Relocation Considerations


• Promotes ecosystem

migration

• Minimizes threats to

humans

• Financially sustainable

in the long-term

– Potentially expensive

for areas that are

significantly

developed

• Politically problematic to

implement

• May be subject to legal

challenge

• Relocation issues


4Chapter

Scenarios

by

Projected

SLR for the

Nile Delta

CASE STUDY


4Chapter

Trend and Accelerated Sea Level Rise

(ASLR) Measured Along the Nile Delta

Coast.

(CoRI-2007), First Scenario

Sea Level

Rise (Cm)

2100

Sea Level

Rise (Cm)

2075

Sea Level

Rise (Cm)

2050

Sea Level

Rise (Cm)

2025

Average

Annual

ASLT

(Cm)

Station

16.012.08.04.00.16Alex.

23.016.2511.55.750.23Al-Burullus

53.039.7526.513.250.53Port Said


4Chapter

Expected SLR Till 2100 by Projected

Increase in Air Temperature

(B1 Scenario (

2100207520502025Year

1.81.81.30.9

Temperature

(ºC)

28 cm27 cm16.0 cm 7.0 cm

ASLR at

Alexandria

35.0 cm32.25 cm19.5 cm8.75 cm

ASLR at

Al-Burullus

72.5 cm64.3 cm39.5 cm18.12 cm

ASLR at

Port Said


4Chapter

Total affected area and its percentage to the

Nile Delta area According to CoRI

measurements till 2100

(Without Mohammed Ali wall and zero level for lakes borders)

2100207520502025Year

832.7748.4691.8633.8

Total Area

Affected

(km2)

3.333.02.572.53

Total % of

the Nile

Delta Area


4Chapter

Total affected area and its percentage to the

Nile Delta Area According to CoRI

measurements till 2100

(With Mohammed Ali wall lakes borders)

2100207520502025Year

183.8139.2134.093.68

Total Area

Affected

(km2)

0.740.560.540.37

Total % of

the Nile

Delta Area


4Chapter

Muhammed Ali Sea Wall Protected

Cultivated Low Lands (1.5m - 2.5m

Below Sea Level)


4Chapter

Abu Quir Bay

Low Lands (1.5 – 2.5 m Below Sea Level)

Protected By Muhammed Ali Sea Wall

Muhammed Ali

Sea Wall


4Chapter

Detached Breakwater

Ras Al-Bar Resort Has Gained Lands After the Construction of

Protection Works


4Chapter

• Sand dunes systems should be treated as the first defensive line for the Nile Delta.

• Decision makers in coastal governorates as well as concerned ministers should be aware ofthe importance of sand dunes systems and their role in protecting the coastal zone of the Nile Delta.

• Consideration should be paid to coastal lakesas one of the most appropriate adaptive measure against sea level rise.

• Coastal international road should be considered as the second protection measure and studies to support it are urgently required.

• Coastal protection constructions need regular maintenance and should be considered in any coastal zone management plans.

• The northwest coast extended from Alexandria to the Egyptian-Libyan borders is not vulnerable as it has elevation more than 10 m above average sea water level.

Adaptive Process and Policies


4Chapter References

1. Global ice and snow presentation, National Aeronautics and Space

Administration, NASA

2. ENVI3410: Coupled Ocean & Atmosphere Climate Dynamics

3. Krystle Macadangdang, LL.M, Melissa Newmons, J.D. Sea Level Rise

Ready.

4. Prof. Ibrahim Elshinnawy, Vulnerability Assessment and Adaptation

Policies for C C Impacts on the Nile Delta Coastal Zones.

Documents

Environment Sea Level Rise - الصفحات الشخصية | الجامعة ...site.iugaza.edu.ps/mabualtayef/files/04-Chapter-4-Ice...Eustatic changes = volumetric (mass) changes