Sea levels: the global scene

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Sea levels the global scene
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Global sea levels Past, present and future
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Variability is increasing
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• Sea-level rise
• inundation
• storm surges, waves
• coastal erosion
• Impacts on emergency and escape routes
• Break down in law and order
• Environmental refugees a here and now issue
• not if but when and where and how will we
  respond?

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Paleo data constrains estimates of sea-level
change over centuries to millenia
Lambeck, Pers. Comm., 2006
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Sea level has fluctuated by more than 120 m over
the last glacial cycle
Church et al., 2001
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Acoustic gauge Port Vila Vanuatu
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The distribution of available sea-level data
improves with time
Church and White, 2006
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Nine tide gauge sites
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Mean sea level is rising
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Beware short-term trends
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GPS location
Solar panels
Radiometer
Altimeter
DORIS location
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Altimetry Sea Level
Seasonal variations removed GIA correction
applied (0.3 mm/year)
Rate 3.2 0.4 mm/year
http//sealevel.colorado.edu
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Interannual variability from altimeter data
Church and White, 2006
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REASONS FOR CHANGE 1910-1990
IPCC 2001
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Title slide
Explosive volcanic eruptions contribute to
variability in global sea levels
Mt Pinatubo eruption in the Philippines, June 15,
1991. Gases and solids injected 20 km into the
stratosphere.
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Bay of Bengal Major Surges 1737 300,000
killed 1864 100,000 1876 100,000 1897 175,000 1970
300,000 (tide plus 6m surge) And at least 23
surge events with over 10,000 killed since
1737 These considered lower limits as economic
damage adds to eventual total (Murty, Flather
and Henry, 1986 Progress In Oceanography Murty
and Flather, 1994 Journal of Coastal Research)
Woodworth et al., in prep.
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Atlantic weather patterns affect Newlyn sea level
variations.
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Some tidal constituents are changing
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GPS separates land movements
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Projected Coastal Megacities 2010 By 2100, tens
of millions/year will have to respond to coastal
flooding Most vulnerable regions are South and
South-East Asia Africa Carribean Indian Ocean
Islands Pacific Ocean Islands.
Tianjin
Dhaka
Seoul
Osaka
Istanbul
Tokyo
New York
Shanghai
Los Angeles
Manila
Bangkok
Lagos
Nicholls, Pers Comm.
Mumbai
Lima
Karachi
Madras
Jakarta
Rio de Janeiro
Buenos Aires
Calcutta
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From IPCC 2007 Rate of sea level rise (mm per
year) Source of sea level rise 19612003
19932003 Thermal expansion 0.42 0.12 1.6
0.5 Glaciers and ice caps 0.50 0.18 0.77
0.22 Greenland Ice Sheet 0.05 0.12 0.21
0.07 Antarctic Ice Sheet 0.14 0.41 0.21
0.35 Sum of individual climate 1.1 0.5 2.8
0.7 contributions to sea level rise Observed
total sea level rise 1.8 0.5 3.1 0.7
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IPCC 2007
6 scenarios means 0.18 to 0.59 m

• BUT
• Excluding future rapid dynamic changes in ice
  flow
• Rise will continue for centuries even if CO2
  stabalised

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Summary

• Sea-level rise is an issue for
• Here and now, The 21st C and The long term
• Need to mitigate to avoid the most extreme
  scenarios
• Need to adapt
• Impacts will be felt through extreme events
  more frequent and more severe
• Need to narrow uncertainties
• Global, local and regional planning to avoid
  disasters

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Using the sea Respecting the sea Managing the sea

• Using the sea
• Respecting the sea
• Managing the sea
• Partnerships for the sea

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1.1
4.5
1.5
China 3.8 ? Indonesia 15
1.4
3.6
3 to 5
2.9
National contributions of marine activities to GDP
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Cruising 2004 13.4 m passenger Now valued at 15
bn per annum worldwide Trebled since 1990 7
annual growth Increase from 10m passengers pa in
2000 to 16m in 2009
Canadian study showed 1.5m income to Vancouver
for each ship call
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UK Cruise revenues
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Fishing
FAO projections 1997-2030 Increase in capture
13.7m tonnes Increase in aquaculture 54 m
tonnes China aquaculture 70 Latin America
capture 57
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Isolated Seamounts 250 Sampled Out of 15,000

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Managing the sea
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