Transcript IOJ_Khan.pps

IMPACTS OF CLIMATE CHANGE ON OUR
COASTLINE
By
Shakira Khan & Edward Robinson
Marine Geology Unit
Department of Geography & Geology
University of the West Indies, Mona
What is Climate Change?
• Is simply a change of climate, that is, a regional change in
temperature and/or weather patterns.
• This term is commonly used interchangeably with "global warming"
and "the greenhouse effect," but is a more descriptive term and
refers to any change in climate over time, whether due to natural
variability or as a result of human activity (IPCC, 2007) .
• The latter refers primarily to the buildup of man-made gases in the
atmosphere that trap the suns heat, causing changes in weather
patterns on a global scale. The effects include changes in rainfall
patterns, sea level rise, potential droughts, habitat loss and heat
stress. The greenhouse gases of most concern are carbon dioxide,
methane, and nitrous oxides (www.nsc.org/ehc/glossary.htm )
What does this mean?
Scientists have identified some of the likely effects:• Rainfall - Some regions will experience more extreme
rainfall while others will experience drought.
• Storms- More frequent and intense storms
• Temperature -both atmospheric and sea surface
temperate are projected to increase
• Sea level - the sea level could rise by more than 40cm
by the end of the century.
Increased Rainfall -The Debris Flow
Flooding and debris flows occur when normally dry gullies fill to overflowing as infiltration
is overwhelmed and all precipitation becomes surface runoff, carrying rock debris.
Geological evidence for this kind of hazard:
Gullies (blue); Marls and muddy sandstones (brown & orange); Debris fans
(darker browns); Significant recent marine erosion event (red bands).
The activity in such systems was well described by Eleanor Jones (1981).
Sea level rise is a natural
consequence of global warming
The International Panel for Climate Change (IPCC)
has examined models of likely sea level rise over
the next hundred years:The models range from a conservative 10 cm to a
high of some 80 cm. Most of the rise will be due
to thermal expansion of seawater, a lesser amount
due to melting of glaciers and ice caps. However,
the rate at which the large ice caps (Antarctica
and Greenland) will melt is still a matter for
debate.
What will this do to a beach?
Cyclic physical processes occurring on
beaches
• Beach Erosion & Accretion- Carbonate beaches
Long Bay, Portland
Progressive Beach recession, Orange Bay, Portland
More intense & frequent storms
13 month period
September 2004- October 2005
3 storms:
Ivan -September 2004
Dennis –July 2005
Emily – July 2005
Wilma – October 2005
http://www.haitiaction.net/News/storm/IVAN/9_9_4.html
Impacts of climate change on cliffed coastlines
Galina, St. Mary
Photo: N. Butterfield
Intense storms result in Boulders moving
joints
When severe wave events occur (hurricanes or tsunami)
blocks of rock can be torn off the cliff face and hurled inland
Communities on rocky
shores can be engulfed
by storm wave debris
Some wave debris can be very big…
Manchioneal one here
Rising sea levels lead to
increased inundation from storm
surge…..
Storm Surge
Hazards
affecting our
coastline
J. Tyndale Biscoe
Copacabanna
STORM SURGE
Annotto Bay – Storm surge
inundation distances
Photo: N. Butterfield
Impact of storm surge on Mangroves
• Threat to Wild life – destruction of Habitat
• Threat to breeding areas, roosting, nesting
and fish nurseries
Impacts on mangroves along the coast
Impacts on coastal areasRetreating coastline
• House destroyed by encroaching sea
Coastline retreat in response to rising sea level
Brune Rule
(A) Beaches follow a characteristic profile
shape based on the wave climate and the
types of sediments.
(B) When sea level rises, the initial effect is
.
inundation;
(C) But 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 profile, which is
usually flatter than the slope just above the
shore.
Source: Titus (1986).
http://users.rcn.com/jtitus/Holding/fig4.html
Shoreline retreat
Negril
Negril Tree
2003 tree line
2003 base of beach
1971 tree line
Between 1971
and 2003
sea level rose
about 8 cm
(IPCC Report , 2007)
1971 base of beach
200 m
Acknowledgements
The Marine Geology Unit would like to thank•
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The Environmental Foundation of Jamaica
Mr. Rafi Ahmad
Miss Deborah-Ann Rowe
Miss Kadean Mitchell
Mr. Richard Coutou
Photos in presentation were taken by MGU, except where noted
THANK YOU!
Sediment and freshwater plume from Rio Grande flood, February 13, 1999
Website
• Further information about the Marine
Geology Unit at the University of the West
Indies
http://www.mona.uwi.edu/geoggeol/mgu/