Climate Change: Implications for Oceans and Human Health

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Climate Change Implications for Oceans and Human
Health Edward Laws School of the Coast and
Environment Louisiana State University
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Ratio of atmospheric CO2 in times past to the
present concentration (RCO2)
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Atmospheric CO2 concentrations during the past
420,000 years based on the composition of air
entrapped in the Vostok ice core.
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Atmospheric CO2 concentrations since the year
1000 AD estimated from ice core data and
monitoring of CO2 at Mauna Loa.
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Why the ocean is becoming acidic
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Saturation state of seawater with respect to CaCO3
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Mechanisms to remove CO2 Dissolution of calcium
and magnesium carbonates in marine
sediments Timeframe several thousand years
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Weathering reactions with crustal
rocks Timeframe several tens of thousands of
years
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Calcification is highly pH sensitive, and
essentially does not occur below c. 7.6. Raven,
J. A., and P. G. Falkowski. 1999. Oceanic sinks
for atmospheric CO2. Plant, Cell and Environment
22 741-755.
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Atmospheric CO2 emissions, historical atmospheric
CO2 levels and predicted CO2 concentrations from
this emissions scenario, together with changes in
ocean pH based on horizontally averaged
chemistry. b, Estimated maximum change in surface
ocean pH as a function of final atmospheric CO2
pressure, and the transition time over which this
CO2 pressure is linearly approached from 280
p.p.m. A, glacial-interglacial CO2 changes B,
slow changes over the past 300 Myr C, historical
changes in ocean surface waters D, unabated
fossil-fuel burning over the next few centuries.
(Caldeira and Wickett, Nature 425 365 (2003))
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Conclusion a Noahs Ark approach may be needed
to prevent many organisms that make calcite or
aragonite from becoming extinct. Timeframe might
be several thousand years
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Global average temperatures compiled by the
Climatic Research Unit, University of East
Anglia, and the Hadley Centre of the UK
Meteorological Office
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• Temperature effects on oceanic and atmospheric
  physics
• Warming effect tends to be greater at high
  latitudes due to water vapor effect
• This pattern is likely to be enhanced by melting
  of sea ice in Arctic
• Thermal inertia of Southern Ocean will suppress
  this effect.

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Change in annual mean surface temperature between
year 2000 and 2100 based on IPCC scenario A2.
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• Changes in meridional thermal gradients
• Poleward expansion of tropics/subtropics
• Slackening of Trade Winds and associated ocean
  current systems
• Poleward shift in storm tracks, particularly in
  Southern Hemisphere
• Less efficient delivery of allochthonous
  nutrients to euphotic zone in tropics and
  subtropics
• Less fish production in tropics and subtropics

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• Increase in evaporation rates
• Increase in precipitation rates, but with much
  regional variability
• More runoff and nutrient delivery to coastal
  areas
• As sea level rises (40 cm by year 2100) more
  coastal habitat for fish
• More fish production in some coastal areas, less
  in others

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Change in precipitation patterns between year
2000 and 2100 based on IPCC scenario A2.
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Sea level rise during the Holocene interglacial
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Sea level rise during the last 8,000 years
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Population growth and mortality from hurricanes
during the 20th century in the southeastern
United States (Walker et al., Oceans 19(2) 24-36
(2006)).
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Projected impact of adaptation on annual number
of people flooded by coastal storm surges
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• Impact of increased CO2 on marine food chains
• Eukaryotic phytoplankton - diatoms,
  dinoflagellates, coccolithophores
• Diatoms favored in dynamic, turbulent systems
• not good competitors in stratified, steady state
  systems
• Coccolithophores very competitive in stratified
  systems, but produce calcium carbonate plates
• ability to compete will be compromised as pH
  drops
• Dinoflagellates will be the winners
• many HABs are dinoflagellates

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• Health effects associated with dinoflagellates
• diarrhetic shellfish poisoning (species of the
  genus Dinophysis)
• neurotoxic shellfish poisoning (Karenia brevis)
• paralytic shellfish poisoning (species of the
  genera Gymnodinium, Alexandrium, and Pyrodinium)
• ciguatera fish poisoning (Gambierdiscus toxicus).

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• Impact of climate change on coral reefs
• Lower pH will suppress calcification
• Increased temperature - bleaching
• More rainfall and runoff - eutrophication and
  sedimentation

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Relationship between sea surface temperature
(SST) in the Indian Ocean and number of cholera
cases in Bangladesh. Source Rita Colwell
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Drip treatment of cholera victims at a refugee
camp in Mozambique. Source Doctors Without
Borders
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A female copepod whose egg case, on the left, is
covered with Vibrio bacteria. Source Dr. Rita
Colwell
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A village woman in Matlab, Bangladesh uses layers
of sari cloth to filter drinking water. Courtesy
of Anwar Huq, University of Maryland
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Reconstruction of global temperature anomalies
during the last 1,000 years.
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A Scene on the Ice by Hendrick Avercamp was
inspired by the harsh winter of 1608 in Europe.
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Valley Forge - 1777-1778
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West Antarctic Ice Sheet