Ocean Acidification Scott Doney

Woods Hole Oceanographic Institution

Rising Atmospheric CO2

IPCC AR5 WG1 Chap. 6

Doney & Schimel Ann. Rev. Env. & Res. 2007

Warm interglacial

Cold glacial

CO2

Temperature

Fate of Human-Driven CO2 Emissions (2003-2012)

LeQuere et al. Earth System Sci. Data 2014 ; Global Carbon Project 2014

~9.5 billion tons carbon per year+

Atmosphere45%

Land29%

Oceans26%

Human-Driven Carbon Sources & Sinks

IPCC AR5 WG1 Chap. 6

2−[CO3 ][CO2]

100−150% 50%

2100

8.2

8.1

8.0

7.9

7.81800 1900 2000 2100

50

40

30

20

10

0

300

240

180

120

60

0

pHμm

ol kg−1

Year

pH

CO2(aq)

CO32−

30% acidity16% [CO3 ]

2000

2−

Wolf-Gladrow et al. (1999)

Ocean Acidification

CO2 + H2O H+ + CO32- HCO3

-H+ + HCO3-

Changing Seawater Chemistry

IPCC 2014WG1, Chapter 3Doney et al. Ann. Rev. Mar. Sci. 2009Dore et al. PNAS 2009

carbonate ion

pH

carbon dioxide

Calcium Carbonate

Ca + CO3 CaCO3 (solid)2-2+

Saturation State

= [Ca2+][CO32-] / Ksp

>1 saturated<1 undersaturated

Excess carbonate ion Δ[CO3

2-] = [CO32-]obs - [CO3

2-]sat

CaCO3 solubility -depends on mineral form-increases with pressure

Feely et al. Nature 2005; Bednaršek Nature Geosci. 2012

Ocean Solubility and Biological Carbon Pumps

http://www.pmel.noaa.gov/co2/story/GOM

Coastal Gulf of Maine Ocean Acidification Mooring

Collapse of Pacific NW Oyster Hatcheries

Coastal Upwelling

Barton et al.Limnol. Oceanogr.2012

Acidification along U.S. East Coast

De

pth

(m

)

Wang et al. Limnology & Oceanography 2013

Distance From Shore (km)

acidic waters

Other Local Sources of Acidification

Doney et al. PNAS 2007; Doney Science 2010; Kelly et al. Science 2011

River Flow Affects Estuaries & Coastal Waters

Sailsbury et al. EOS 2008

Varies with river chemistry (natural & pollution)

Aufdenkampe et al. Frontiers in Ecology & Environment 2011

Excess Nutrients, Low Oxygen & Coastal Acidification

Wallace et al., Estuarine, Coastal & Shelf Science, 2014

Marine Life Susceptible to Ocean Acidification

-Reduced shell formation -Habitat loss-Less available prey

Negative Impacts of CO2 on Mollusks

Talmage et al. PNAS 2010

Present

Future(estuaries)

Eastern Oyster Larvae

Synthesis of biological impacts

Kroecker et al. (2009; 2013)

Detrimental Effects

All types of organisms tested

Pacific NW Oyster Hatcheries

Barton et al.Limnol. Oceanogr.2012

Acidification & Past Geologic Extinction Events

Time moving forward to the left

Hönisch et al. Science 2012

Calcareous organism response not uniform; importance of other environmental factors to extinction, adaptation & evolution

Summary Points

-Atmospheric carbon dioxide (CO2) rising because of human emissions (mostly fossil fuel burning)

-About ¼ of human CO2 emissions enter the ocean, changing seawater chemistry

• more acidic (lower pH)• calcium carbonate shells more soluble

-Coastal acidificatoin can occur because of excess nutrients (and other processes)

-Acidification potentially threatens many shellfish

Extra Slides

Dissolved Inorganic Carbon (DIC): total concentration of all carbon speciesAlkalinity: acid buffering capacity (weak anions, 2*CO3

2- + HCO3-)

pCO2: partial pressure of carbon dioxidepH: hydrogen ion activity

Ocean Inorganic Carbon & Alkalinity Distribution

Dissolved inorganic carbon (DIC)

Alkalinity

Vertical DIC gradient~1/3 thermal~2/3 biological

Projecting Future Ocean Acidification Trends

IPCC AR5 WG1 Chap. 6

Anthropogenic CO2 Distribution & Uptake

Sabine et al., Science, 2004; Gruber et al., GBC, 2009

How Long Will Anthropogenic Carbon Dioxide and Its Climate Impacts Persist?

IPCC AR5 WG1 Chap. 6

“Thus human beings are now carrying out a large scale geophysical experiment…”Revelle and Suess, Tellus, 1957

Rising Atmospheric CO2

Ice core data

Changing Seawater Chemistry

Doney et al. Ann. Rev. Mar. Sci. 2009Dore et al. PNAS 2009