Ocean Acidification: The Other CO2 Problem · Ocean acidification: the other COOcean acidification:...
Transcript of Ocean Acidification: The Other CO2 Problem · Ocean acidification: the other COOcean acidification:...
Ocean acidification: the other CO2 problemOcean acidification: the other CO2 problem
Andreas J. AnderssonScripps Institution of
Oceanography
Andreas J. AnderssonScripps Institution of
OceanographyOceanography
Photo: Alex Venn
Number of Ocean Acidification publications over time
Gattuso and Hansson, 2011
• What is ocean acidification?
• What is the evidence for ocean acidification?
• How will the acid-base balance of the ocean change in the future?
• Why are we concerned about ocean acidification?
• How and what do we know about the future consequences of OA to marine ecosystems?
• What are the implications to humans from ocean acidification?
• How can ocean acidification be prevented?
Fate of Anthropogenic CO2 Emissions (2000-2008)
Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS, updated
1.4 PgC y-1
+7.7 PgC y-1
3.0 PgC y-1
29%
4.1 PgC y-1
45%
26%2.3 PgC y-1
What is ocean acidification?
1. CO2 (g) atm. → CO2 (g) sw.
2. CO2+ H2O → H2CO3
3. H2CO3 → H+ + HCO3-
4. H++ CO32- → HCO3
-
CO2
CO2
N. Bates, BIOS
What is the evidence for ocean acidification?
What is the evidence for ocean acidification?
IPCC 2007
How will the acid-base balance of the ocean change in the future?
1980 2000 2020 2040 2060 2080 2100
pH reduction by 0.3-04 units by 2100 ~ 100-150% increase in acidity
Joos et al. 2011
Why are we concerned about ocean acidification?
• Seawater acid-base balance important in regulating biological and chemical processes, e.g.:– Function of enzyme and proteins– Chemical reaction rates– Availability of nutrients and trace metals
• CO32- is an essential building block for marine
organisms depositing skeletons or shells made of CaCO3– Less building material equals slower growth, weaker structures
(similar to osteoporosis in humans) and increased vulnerability to environmental stress in general
Winners and losers
Alex Venn
http://www.noaanews.noaa.gov
How and what do we know about the future consequences of OA to marine ecosystems?
• Geologic record• Experimental manipulations• Natural high CO2 environments• Model simulations
Geologic record
Paleocene-Eocene Thermal Maximum (55 Mya)-Rapid increase in temperature (5-9 ºC)-Rapid increase increase in CO2 and OA-Extinction of forams, coral reefs declined
Cooper et al. 2008
Photo: Hannes Grobe, AWI
Experimental manipulations
Credit: Chris Langdon
Photo: Kim Yates
Natural high CO2 environments
Hall-Spencer et al. 2008
Fabricius et al. 2011
• Change microbial processes and biogeochemical cycles
• Affect marine organisms: positive, negative or no effect– different effect on different life stages
• Changes in community structure, food web dynamics, and biodiversity– coral reefs transition to net erosion
Based on current evidence: what do we know about the effects of OA to marine ecosystems?
To what extent and at what rate will these changes occur?
What are the implications to humans from ocean acidification?
• Food security• Economic impacts
– Fisheries– Tourism
• Coastal protection– Erosion– Storms, hurricanes– Tsunamis
Hypothesized future transition of coral reefs
Hoegh-Guldberg et al. 2008
How can ocean acidification be slowed down or prevented?
• Reduce atmospheric CO2 emissions
• Increase buffer capacity of seawater
– Natural feedback to ocean acidification: CaCO3sediment dissolution and weathering
– Proposals to add limestone (CaCO3) to ocean
What about geoengineering solutions?
Potential strategy but could also create more risk (e.g., AMS, Royal Society)
• Solar Radiation Management (SRM) – do not address OA– Sulfur dioxide– Space shades• Carbon Dioxide Removal (CDR) – Carbon Capture and Storage– Ocean fertilization– Forestation
At research stage and largely unproven, limited analysis of practicality, cost and benefits, and environmental consequences