Sea Level Rise, Hurricanes, Coastal Adaptation

Peter Webster

Sea Level RiseRed: sea level rise ca. 2100Blue: storm surge major hurricane

IPCC indicates likely [>66%] increase of 1-2 feet by 2100(does not include accelerated or catastrophic melting of ice sheets)

Recent estimates: 1.4 m rise by 2100 is plausible

WMO

UNEP

UNEP

IPCC AR4: Hurricanes

There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures (SST)

It is likely [>66%] that future tropical cyclones will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs

Since 1995, there has been a shift in the intensitydistribution towards more major hurricanes

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

1970-1982 1983-1994 1995-2006

TS

Cat1

Cat2

Cat3

Cat4

Cat5

Intensity Distribution of North Atlantic Tropical Cyclones

Increased tropical cyclone activity since 1970,

correlated with increasing sea surface temperatures

For a 2.5oC (5oF) temperature increase:

• 0-30% increase in number of North Atlantic tropical cyclones

• 10% increase in tropical cyclone intensity equivalent to 33% increase in damage

• 30% increase in the number of major hurricanes

Climate model projections of future hurricane activity

3 major hurricanes struckGA coast in the 1890’s

Landfall near Brunswick as a Cat. 4 with max winds of 135 mph

180 dead; $56.5 million in damage (2004 dollars)

Max storm surge was 13-18 ft. in Darien

http://www.srh.noaa.gov/jax/research/hurricanes/history/1898/

Oct 1898 – Georgia Hurricane

3 major landfalls in the 1890’s (but none since 1900)

Potential for big storm surge owing to shallow shelf

Barrier islands at extra risk associated with sea level rise

Risks to Coastal Georgia

Impacts of floodsImpacts of floods

Hurricane Frances (2004) caused $41M damageto Atlanta from flooding

Immediate impacts: property damage, injuries, death

Health issues: infectious diseases, exposure to toxins

Key water quality issues:

• Floodwater tainted with raw sewage, pesticides, agricultural waste, petroleum products, dead animals

• Flooding of animal waste retention pools from hog, cattle, dairy, poultry farms

Case Study: Hurricane Ivan (2004) Category 3 hurricane that made

landfall just west of Gulf Shores, AL

Produced 25 tornadoes in GA resulting in 2 deaths and 10 injuries.

Rainfall in excess of 5 to 10 in. and high winds destroyed 50% pecan and 15% cotton crop in GA.

Property damage in GA $68.8 M.

From National Climatic Data Center Satellite Archives

While no major hurricane strikes since 1900, increases in # of Atlantic storms increases the probability of a GA landfall

Landfall on GA coast has potential for big storm surge owing to shallow shelf

Barrier islands at extra risk associated with sea level rise

Heavy rainfall associated with storms that make landfall in the Gulf; rainfall in hurricanes is expected to increase

Tornadoes likely to be spawned in GA by increasingly intense storms that make landfall in the Gulf

Hurricane Risks to Georgia

Coastal ecosystems will eventually adapt, but hurricanes will cause short term damage to maritime forests, wetlandsmarshes, and wildlife disruptions

Human systems will face shoreline erosion, loss of beachesand dunes, damage to structures, economic losses. Adaptation strategies include:Land useCoastal engineeringBuilding codesWetlands preservationForest preservation

Adaptation Strategies