Ocean Acidification Scott Doney Woods Hole Oceanographic Institution

Rising Atmospheric CO 2 IPCC AR5 WG1 Chap. 6 Doney & Schimel Ann. Rev. Env. & Res Warm interglacial Cold glacial CO 2 Temperature

Fate of Human-Driven CO 2 Emissions ( ) LeQuere et al. Earth System Sci. Data 2014 ; Global Carbon Project 2014 ~9.5 billion tons carbon per year + Atmosphere 45% Land 29% Oceans 26%

Human-Driven Carbon Sources & Sinks

IPCC AR5 WG1 Chap. 6

2− [CO 3 ][CO 2 ]  100−150%  50% pH μmol kg −1 Year pH CO 2(aq) CO 3 2−  30% acidity  16% [CO 3 ] − Wolf-Gladrow et al. (1999) Ocean Acidification CO 2 + H 2 OH + + CO 3 2- HCO 3 - H + + HCO 3 -

Changing Seawater Chemistry IPCC 2014 WG1, Chapter 3 Doney et al. Ann. Rev. Mar. Sci Dore et al. PNAS 2009 carbonate ion pH carbon dioxide

Calcium Carbonate Ca + CO 3 CaCO 3 (solid) 2-2+ Saturation State  = [Ca 2+ ][CO 3 2- ] / K sp  >1 saturated  <1 undersaturated Excess carbonate ion Δ[CO 3 2- ] = [CO 3 2- ] obs - [CO 3 2- ] sat CaCO 3 solubility -depends on mineral form -increases with pressure Feely et al. Nature 2005; Bednaršek Nature Geosci. 2012

Ocean Solubility and Biological Carbon Pumps

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 Depth (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 CO 2 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 (CO 2 ) rising because of human emissions (mostly fossil fuel burning) -About ¼ of human CO 2 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 species Alkalinity: acid buffering capacity (weak anions, 2*CO HCO 3 - ) pCO 2 : partial pressure of carbon dioxide pH: 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 CO 2 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 CO 2 Ice core data

Changing Seawater Chemistry Doney et al. Ann. Rev. Mar. Sci Dore et al. PNAS 2009