Ocean uptake of Atmospheric CO2 and the Impact of Ocean Acidification on Marine Organisms Dr. Christopher L. Sabine

Director, NOAA’s Pacific Marine Environmental Laboratory Seattle, Washington USA

Outline:

• The ocean’s role in controlling atmospheric CO2 • Resulting changes in ocean chemistry • Ocean acidification effects on marine organisms

Acknowledgements: R Feely (PMEL), R. Wanninkhof (AOML), G.-H. Park (AOML), K. Shamberger (PMEL), P. Canadell (CSIRO), J. Dore (U. Montana), S. Cooley (WHOI), K. Caldeira (Stanford), D. Gledhill (AOML), J. Corredor (UPR), A. Barton (Taylor Shellfish), etc.

Outline:

• The ocean’s role in controlling atmospheric CO2 • Resulting changes in ocean chemistry • Ocean acidification effects on marine organisms

Take home message: There is growing evidence that human release of carbon dioxide will have a profound impact on marine ecosystems, but without the necessary biological and geochemical observations in the ocean it will be extremely difficult to attribute any ecosystem changes to ocean acidification.

Atmospheric CO2 was steady for at least 1,000 years before the industrial revolution.

Slope 1.9 ppm/yr

Adapted from Sarmiento and Gruber 2002 using Trends online data

Fate of Anthropogenic CO2 Emissions (2000-2009) Deforestation 1.1±0.7 Pg C y-1 1 Petagram = 1015grams = 1 billion metric tonnes

1 metric tonne = 1.1 US tons

+

Fossil Fuel burning 7.7±0.5 Pg C y-1

• 1 railroad hopper car can carry about 100 US tons of coal which is 80% carbon

Total deforestation ~

• 1 hopper car is about 60 feet long including its couplings. 73,000 km2 each year • (1 Petagram) x (1.102 x 10^9 tons/Pg) x An area about of Panama (1car/100 tons) xthe (60 size feet/car) x (1/0.8) x (1mile/5280feet) = 1.565 x 10^5 miles = 156,500 miles • Circumference of Earth at equator = 24,902 miles

• ASorailroad a railroad train carrying Pg carbon of train carrying 9 Pg1 of carbon would stretch the 54 Earth 6 would stretch around around the Earth times! times. Global Carbon Project 2010; Updated from Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS

Fate of Anthropogenic CO2 Emissions (2000-2009) 1.1±0.7 Pg C y-1

4.1±0.1 Pg C y-1

Atmosphere 47%

+

7.7±0.5 Pg C y-1

2.4 Pg C y-1

Land 27%

2.3±0.4 Pg C y-1

Oceans 26%

Global Carbon Project 2010; Updated from Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS

Carbon Changes at the Hawaii Ocean Time-series (HOT) site

Station Aloha

Mauna Loa

Surface water pCO2 is increasing at about the same rate as atmosphere We see a commensurate decrease in pH with the rise in surface water pCO2 Doney, Science, 2010 Dore et al., PNAS 2009

Ocean Acidification: Fundamental Chemistry

CO2 H2O 

carbon dioxide





+

H  CO  HCO   + 

water

 H HCO3

H2CO 3

hydrogen ion

2

carbonic acid3

carbonate ion

+  hydrogen 3 ion

bicarbonate ion

bicarbonate ion

• More than 99% of the H+ formed consume CO32- to form HCO3- making it more difficult for organisms to form their shells. CO2 is an acid gas so the addition of 22 million tons of carbon dioxide to the ocean every day is acidifying the seawater…we call this process “ocean acidification”

Ocean Acidification: Fundamental Chemistry

Ca2+

+

CO32-

CaCO3

+

Calcification Index

W

Saturation State

[ Ca2+ ][CO32- ] phase = K*sp,phase

W>1 CaCO3 stable W=1 equilibrium W