Impacts of Global Warming on Coastal Resources in Rhode Island Janet Freedman, Coastal Geologist RI

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Impacts of Global Warming on Coastal Resources in
Rhode Island Janet Freedman, Coastal Geologist
RI Coastal Resources Management CouncilGasping
for AirClimate Change in the CourtsMarine
Affairs InstituteRoger Williams School of
LawFebruary 7, 2007
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Abstract
Impressionist 30 years ago
The picture is very clear yet the closer you get
to a particular pixel (increased storminess,
hurricane intensity, rate of sea level rise) the
harder it is to be precise.
Pointillist today
Andrew Revkin, NY Times 01-14-07
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Climate Change 2007 The Physical Science
Basis Summary for Policymakers Working Group 1 -
IPCC
Findings Global ocean temperatures
have increased to a depth of 3000 m since
1961 Global sea level rose at an average rate of
1.8 mm/yr over 1961-2003 Global sea level rose
an average of 3.1mm/yr over 1993 to 2003. It is
unclear how much of this rate of rise reflects
decadal variability. There is a high confidence
that the rate of observed sea level rise
increased from the 19th to 20th century
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Climate Change 2007 The Physical Science
BasisSummary for PolicymakersWorking Group 1 -
IPCC
Projected globally averaged sea level rise at the
end of the 21st Century range from 0.18 m to 0.59
m Thermal expansion will continue for
centuries Dynamical processes related to ice
flow not included in current models but suggested
by recent observations could increase the
vulnerability of ice sheets to warming,
increasing future sea level rise
Roger J. Braithwaite, The University of
Manchester, UK
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Sea Level Rise

• Eustatic thermal expansion (steric change)
• melting glaciers (mountain, Greenland and
  Antarctic Ice Sheets)
• Isostatic land moves up and down (lithosphere
  responds to ice or sediment loading, tectonic
  movements, land subsidence due to extraction
  of water, oil)
• The combination of eustatic and isostatic sea
  level changes is know as relative sea level
  change

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2.57 mm/yr /-0.11 mm 1930-1999 1.8 mm/yr
eustatic slr 0.77 mm/yr isostatic slr
3.98 mm/yr /-0.11 mm 1911-1999 1.8 mm/yr
eustatic slr 2.18 mm/yr isostatic slr
Data from NOAA sea levels online
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9.85 mm/yr /-0.35 mm, 1947-1999 1.8 mm/yr
eustatic slr 8.05 mm/yr isostatic slr
Data from NOAA sea levels online
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Sea Level Rise

• Increased erosion
• Salt water intrusion
• Groundwater contamination
• ISDS failure
• More susceptibility to storm surge
• Effect properties further inland
• Effect properties that are now elevated out of
  the perceived harms way

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Factors influencing coastal erosion

• Storm surge and waves
• Underlying substrate (bedrock, unconsolidated
  gravel, sand, silt)
• Lack of sediment source
• Sea Level Rise

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Storm surge and waves
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Cracked foundation
Exposed ISDS
Headland erosion
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Underlying substrate (sand, silt) easily eroded
Sand eroded undermined foundation
Aeolian silt
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Underlying substrate (bedrock) resistant to
erosion
Rocky shoreline, cliffs much less susceptible to
storm induced erosion
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Sediment sinksflood tidal delta
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Sediment sinks Offshore transport during
storms(gt35 ft)
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Sea Level Rise
As sea level rises storm surge and storm waves
impact areas further landward
IPCC 2007 finds that heavy precipitation events
frequency likely increased since 1960 and is very
likely to continue in the 21st century
IPCC 2007 finds that intense tropical cyclone
activity likely increased in some regions since
1970 and the trend will likely continue in the
21st century
IPCC 2007 finds that the incidence of extreme
high sea levels likely increased since 1960 and
the trend will likely continue in the 21st century
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Impacts of Coastal Erosion
From RIDEM website
Loss of recreational beach area
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Loss of facilities
2005
1998
2005
2006
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Matunuck Headland circa 1950
Ocean Mist
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ISDS
Infrastructure threatened ISDS damage (public
health concerns)
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Brownings Cottages Historic District
1992
1972
Houses threatened again ISDS damaged
Houses moved 50 feet landward
1999
2007
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Shoreline Protection Structures (beaches or
structures)

• Loss of access
• Disruption of sediment transport
• Localized erosion

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Some other climate change impacts to coastal
resources

• Wetlands loss
• sea level rise
• introduction of new pathogens (sudden wetlands
  dieback)
• Ocean Warming
• Ecosystem change
• early ctenophore blooms in Narragansett
  Bay
• stresses to eelgrass beds

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Benefits of eelgrass (Zostera marina)

• Provides refuge and nursery areas for important
  finfish and shellfish species
• Critical substrate for epiphytic communities
• Acts as a natural filter utilizing nutrients and
  causing suspended sediment to settle
• Provides a food source for higher trophic level
  species

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Impacts of Temperature and Nutrients on Coastal
Lagoon Plant Communities Joanne C. Bintz, Scott
W. Nixon, Betty A. Buckley, and Stephen L.
Granger
Temperature treatments controls that
approximated the 9-yr mean daily temperatures for
Ninigret and Point Judith Lagoons in Rhode Island
treatments approximately 4C above and 4C below
the controls Nutrient treatments addition of 6
mmol N m-2 d-1 and 0.5 mmol P m-2 d-1 to
mesocosms 4C above and 4C below the 9-yr daily
mean Results By the end of summer, virtually all
of the measures of eelgrass health declined in
rank order from cool, to mean, to cool enriched,
to warm, to warm enriched treatments Interpretatio
n It is likely that the marked declines in
eelgrass abundance observed during recent decades
in the Northeast have resulted from an
interaction of increasing nutrient enrichment
combined with increasing summer water
temperatures.
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Timing and size of blooms of the ctenophore
Mnemiopsis leidyi in relation to temperature in
Narragansett BayRIBarbara K. Sullivan,
Donna Van Keuren and Michael Clancy
Blooms have typically been observed in late
summer and fall in Narragansett Bay according to
records from 1950 to 1979.
During 1999, M. leidyi appeared earlier in spring
and was more abundant than during any previous
year for which records are available
Effects on planktonic ecosystem dynamics of
Narragansett Bay Likely reduce zooplankton
abundance in spring followed by increases in size
and frequency of summer phytoplankton blooms.
may also reduce survival of eggs and larvae of
fish because, as in 1999, they coincide with the
period of peak spawning.
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Conclusions

• Sea level will continue to rise in response to
  global warming
• The ice sheet flow for the Greenland and
  Antarctic Ice Sheets could increase in the
  future, increasing the rate of sea level rise
• The frequency of tropical and extra-tropical
  storms are likely to increase in the future
• Rising sea levels contribute to the net loss of
  shoreline, and threaten structures and
  infrastructure
• Increasing rates of sea level rise in RI may
  result in wetlands loss
• The oceans will continue to warm for centuries,
  adding to sea level rise and impacting ecosystems