SAB ~4 month (17 week) Cycle

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Ocean Acidification Global Warmings Evil Twin
2008 NASA Carbon Cycle Ecosystems Joint Science
Workshop
Richard A. Feely NOAA/Pacific Marine
Environmental Laboratory April 30, 2008
With special thanks to Carol Turley, Chris
Sabine, Jim Orr, Fei Chai, Chris Langdon, Barney
Balch, Rik Wanninkhof, Dwight Gledhill, Anne
Cohen, Justin Ries, and Sylvia Barry
Outline What is ocean acidification? What are the
impacts on marine organisms? Satellite-based
approaches to investigate ocean
acidification Conclusions
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Ocean Acidification

• Since the beginning of the industrial age, the pH
  and CO2 chemistry of the oceans (ocean
  acidification) have been changing because of the
  uptake of anthropogenic CO2 by the oceans.
• Decrease in pH 0.1 over the last two centuries
• 30 increase in acidity decrease in carbonate
  ion of about 16

These changes in pH and carbonate chemistry may
have serious impacts on open ocean and coastal
marine ecosystems.
http//www.biol.tsukuba.ac.jp/inouye
Photo Missouri Botanical Gardens
Corals
Calcareous Plankton
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What we know about the ocean chemistry
of saturation state
W
gt

1
precipitation
calcium
carbonate
calcium carbonate
W


1
equilibrium
W
lt

1
dissolution
 
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What we know about ocean CO2 chemistry
from field observations
WOCE/JGOFS/OACES Global CO2 Survey
72,000 sample locations collected in the 1990s
DIC 2 µmol kg-1 TA 4 µmol kg-1
Sabine et al (2004)
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What we know about ocean CO2 chemistry
about human impacts on ocean CO2 chemistry

• From the WOCE/JGOFS global CO2 survey, the
  observed anthropogenic CO2 inventory through 1994
  is calculated to be 11819 Pg C.

• Because the ocean mixes slowly, half of the
  anthropogenic CO2 stored in the oceans is found
  in the upper 10 of the ocean

• What are the impacts of increased CO2 on marine
  ecosystems?

Sabine et al. Science (2004)
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What we know about ocean CO2 chemistry
from observed aragonite and calcite saturation
depths in the global oceans
Feely et al. (2004)
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What we know about ocean CO2 chemistry
from observed shoaling saturation horizons
Global Water-column Dissolution 0.5 Pg C yr-1
The aragonite and calcite saturation horizons
have shoaled towards the surface of the oceans
due to the penetration of anthropogenic CO2 into
the oceans.
Feely et al. (2004)
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Predictions of Ocean Acidification and the
effects on coral reef calcification

• Coral Reef calcification
• 1765 Adequate
• 2000 Marginal
• 2100 Low

Calcification rates in the tropics may decrease
by 30 over the next century
After Feely et al (in press) with Modeled
Saturation Levels from Orr et al (2005)
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Experiments on Many Scales
Large Scale Mesocosm Facility University of
Bergen, Norway
Biosphere 2
190
370
700
pCO2 (ppmv)
SHARQ Submersible Habitat for Analyzing Reef
Quality
Provided by Mark Eakin
Aquaria and Small Mesocosms
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The impact of rising atmospheric CO2 on the
surface ocean carbonate chemistry and its
potential impact on corals - Biosphere 2 Results
1870
2006
Glacial
560
280
380
180
840
R2 0.843
Net Calcification
Net Dissolution
Carbonate ion concentration
Low CO2
High CO2
Langdon Atkinson, (2005)
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Some evidence that shallow corals can survive in
polyp form without a calcified structure
(A) Oculina patagonica Control colony
(B) Sea anemone-like polyps following skeleton
dissolution in low-pH conditions
1mm
1mm
(C) Solitary polyps reform a colony and calcify
after being transferred back to normal seawater
following 12 months as soft-bodied polyps in
low-pH conditions
1mm
(D) percent change (average SE) in protein per
polyp (biomass) and total buoyant weight over 12
months in experimental (pH 7.4) and control (pH
8.2) seawater (N20). A two-way analysis of
variance (time x pH) revealed significant changes
between treatments over time
Fine Tchernov, 2007
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Scorecard of Biological Impacts of Ocean
Acidification
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What we know about the biological impacts of
ocean acidification
...and sensitivity to CO2/pH perturbation

• Much of our present knowledge stems from
• abrupt CO2/pH perturbation experiments
• with single species/strains
• under short-term incubations
• with often extreme pH changes

• Hence, we know little about
• responses of genetically diverse populations
• synergistic effects with other stress factors
• physiological and micro-evolutionary adaptations
• species replacements
• community to ecosystem responses
• impacts on global climate change

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CaCO3 Flux Estimates for the Oceans
Flux Estimate mmol CaCO2 m-2 d-1
Flux Estimate Pg C yr-1
Flux Term
Dissolution from 200 to 1500m
data from Honjo et al. (2008)
Updated from Berelson et al., (2007)
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Optical estimate PIC is acid-labile
backscattering (bb)

• Measure particulate backscattering (bbp) with
  single detector, using raw seawater bbp raw
• Reduce pH below dissociation point for calcite
  and aragonite (i.e. dissolve CaCO3)
• Re-measure bbp bbp acid
• bb bbp raw bbp acid
• PIC mol PIC(m -3) bb/bb
• Good for ship surveys, 2-4 minute pH cycle,
  resolution of 1-2 samples/km

-W.M. Balch
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Two PIC Algorithms

• Two band algorithm (based on absolute nLw440 and
  nLw550) Balch et al. (2005 Calcium Carbonate
  Measurements in the Surface Global Ocean based on
  MODIS Data. JGR-Oceans 110, C07001
  doi10.1029/2004JC002560)
• Better at background PIC concentrations,
  saturates at high PIC, atmospheric correction
  large, provides chl estimate, sensitive to errors
  in absolute nLw.
• Three-band algorithm (based on 670, 765, and
  865nm bands Gordon et al. (2001. Retrieval of
  coccolithophore calcite concentration from
  SeaWiFS imagery, Geochemical Research Letters, 28
  (8), 1587-1590.)
• Best in turbid water, less problems from
  atmospheric correction, little complication from
  chl or CDOM

-W.M. Balch
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Particulate Inorganic Carbon Concentrations from
Satellite Observations
Lets compare PIC observations from ship and
satellite
AMT 17 Cruise track
NOTE THESE ARE NOT BLOOMS BUT NORMAL BACKGROUND
PIC CONCENTRATIONS!
-W.M. Balch
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Global calcite MODIS Aqua
-W.M. Balch
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Conclusions

• Impacts of ocean acidification on ecosystems are
  largely unknown.

• Calcification in many planktonic organisms is
  reduced at elevated CO2, but the response is not
  uniform.

• Possible responses of ecosystems are speculative
  but could involve changes in species composition
  abundances - could affect food webs,
  biogeochemical cycles.

• Satellite measurements and observational data can
  be integrated to provide global views of changing
  ecosystem dynamics and carbonate budgets.