Sea Level Rise –
A Global Problem
in Your Backyard
ESI
When sea level rises……
west
How does the slope of the land
influence the loss of shoreline?
east
What happens
to the island?
Steeper slope
Gentle slope
Maryland Shoreline
Most biological
productive areas are
between present sea
level and 1.5 meters
above.
A one foot rise in sea level will
inundate about one mile of shore!
http://www.epa.gov/globalwarming/publications/impacts/sealevel/maps/maps.html
How can sea level change?
Can rise or fall
How do we know sea level changed?
World-wide tide gauges with over 100 yrs of data
Local geological evidence such as
finding marsh deposits offshore
Tide Gauges in the Bay
What do they tell us?
Baltimore
7150
7200
7100
7150
7050
7000
6950
6900
y = 3.5195x + 36.12
6850
R2 = 0.8579
6800
6750
1920
1930
1940
1950
1960
1970
1980
1990
2000
sea level, mm
sea level, mm
Annapolis
7100
7050
7000
6950
y = 3.1409x + 840.94
6900
R2 = 0.9039
6850
6800
6750
1880
2010
1900
1920
1940
Hampton Roads
2000
2020
Solomons Island
7250
y = 4.3933x - 1602.8
R2 = 0.8762
1930
1940
1950
1960
1970
year
1980
1990
2000
2010
sea level ,mm
sea level, mm
1980
year
year
7300
7250
7200
7150
7100
7050
7000
6950
6900
6850
6800
6750
1920
1960
7200
7150
7100
7050
y = 3.4338x + 303.08
7000
R2 = 0.8287
6950
6900
1930
1940
1950
1960
1970
1980
1990
2000
year
3-4 mm/year or 30-40 cm/century increase in sea level
2010
What is different about Stockholm
compared to the Bay and world in general?
What causes sea level to change?
http://www.pol.ac.uk/psmsl/psmsl_individual_stations.html
(save as text file, space separated to load into Excel)
Tide gauge
increase due to
climate warming
decrease due to
climate cooling
present sea level
Tide gauge
decrease due
to land rising
increase due to
land subsidence
present sea level
Tide gauge
What about an area with
excessive sediment input,
does sea level change?
present sea level
Sea level remains constant, the container
holding the water (oceans) is very large.
Relative Sea Level Change
• Climate warming
Glacial ice melts and seawater volume expands
• Climate cooling
More 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
In the Chesapeake Bay region…
• World-wide sea level increase due to
global warming – thermal expansion of
seawater and glacial ice melting
• Land subsidence, especially the eastern
shore, due to groundwater withdrawal
for agriculture
• Both contribute to a relative sea level
rise
Sharp’s Island at month
of the Choptank River
What happened to the island?
Sharp's Island Land Area
Area, km2
4.0
3.0
2.0
1.0
0.0
1600
1650
1700
1750
1800
1850
1900
1950
Year
From S.P. Leatherman, formerly of UMCP Geography
2000
Sharp’s Island – It isn't no more!
aerial view
Sea
level
rise
side view
In 1962 the island vanished in a winter storm!
Increase in erosion of island