IMPACTS OF CLIMATE CHANGE ON OUR COASTLINE

By Shakira Khan & Edward Robinson

Marine Geology UnitDepartment of Geography & GeologyUniversity 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.

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.

Increased Rainfall -The Debris Flow

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

http://www.haitiaction.net/News/storm/IVAN/9_9_4.html

13 month period

September 2004- October 2005

3 storms:

Ivan -September 2004

Dennis –July 2005

Emily – July 2005

Wilma – October 2005

Galina, St. MaryPhoto: N. Butterfield

Impacts of climate change on cliffed coastlines

When severe wave events occur (hurricanes or tsunami)blocks of rock can be torn off the cliff face and hurled inland

joints

Intense storms result in Boulders moving

Some wave debris can be very big…

Communities on rocky shores can be engulfed by storm wave debris

Manchioneal one here

Rising sea levels lead to increased inundation from storm

surge…..

Storm Surge

STORM SURGE

Hazards affecting our

coastline

Copacabanna

Annotto Bay – Storm surge inundation distances Photo: N. Butterfield

J. Tyndale Biscoe

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 areas- Retreating coastline

• House destroyed by encroaching sea

Coastline retreat in response to rising sea level

(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

.

Brune Rule

Shoreline retreat

1971 base of beach

1971 tree line

2003 base of beach

2003 tree line

Negril Tree

200 m

Between 1971 and 2003

sea level roseabout 8 cm

(IPCC Report , 2007)

Negril

Acknowledgements

The Marine Geology Unit would like to thank-

• 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/