1. Ocean Acidification Lecture
Images from Washington State Blue Ribbon Panel on Ocean Acidification Report, 2012
Hilary Palevsky

2. Absorbing CO2 changes ocean pH
Gary Braasch Photography
Hawaii (Mauna Loa)
South Pole
Gary Braasch Photography
Hawaii (ALOHA)
Bermuda (BATS)
Canary Is. (ESTOC)
This slide shows increasing atmospheric CO2 at Mauna Loa in Hawaii and at the South Pole (a), and that at the same time, CO2 in the ocean has been increasing and pH has been decreasing at the three locations where we have been measuring for a long time. The pictures on the right show the work that goes into collecting all the data in these graphs – the top two are of the atmospheric CO2 time series at Mauna Loa and the bottom picture is of a UW Oceanography undergraduate student measuring ocean pH in a lab on a research ship.
ESTOC = Estación Europea de Series Temporales Oceánicas de Canarias
BATS = Bermuda Atlantic Time Series
ALOHA = A Long-term Oligotrophic Habitat Assessment (at HOT = Hawaii Ocean Time-series)
IPCC AR5, Figure SPM.4

3. What is pH all about anyway?
pH = -log[H+]
Decrease in pH = increase in acidity
Logarithmic scale
A decrease of 1 unit is a 10× increase in [H+]
A decrease of 0.1 unit (observed to date) is a 26% increase in [H+]
Figure from WA State Blue Ribbon Panel on Ocean Acidification

4. Ocean carbonate chemistry
CO2 dissolution in water:
CO2 + H2O ↔ H2CO3
H2CO3 ↔ H+ + HCO3-
HCO3- ↔ H + + CO32-
Forming CaCO3 shells:
Ca2+ + CO32- ↔ CaCO3
Ω = [Ca2+][CO32-]/Ksp
When Ω < 1, water is undersaturated and CaCO3 will dissolve

5. Calcifying organisms
Geoduck
Blue mussel
Pink calcifying algae
Urchins
Dungeness crab
Juvenile king crab
Examples of Puget Sound organisms that build shells, skeletons or other hard parts from CaCO3
Images from Washington State Blue Ribbon Panel on Ocean Acidification Report, 2012

6. Pteropods: OA poster child
Zooplankton, swimming snail
Food for young salmon
Shells dissolve in low pH waters
Observed dissolution in situ in Southern Ocean (Bednaršek et al., 2012)
Images from Washington State Blue Ribbon Panel on Ocean Acidification Report, 2012
Pteropods dissolve in water with pH and carbonate chemistry expected for 2100

7. OA in the California Current System
This figure is from a paper that uses a model to show how pH and the aragonite saturation state off the west coast of the US have changed over the industrial period and are projected to change in the future.
Caption from Gruber et al. 2012: Temporal evolution of ocean acidification in the California CS from 1750 until 2050 for the A2 scenario. (A to C) Maps illustrating the evolution of annual mean surface pH, showing the decrease in pH for 1750, 2005 and (D to F) Offshore depth sections depicting the general decrease of the annual mean saturation state of seawater with regard to aragonite and the shoaling of the saturation depth (i.e. omega_arag = 1) for the same three years. The white lines in (A) to © indicate the position of the offshore section.
Gruber et al., 2012

8. OA in the California Current System
Feely et al., 2008
These data are from real measurements made off the west coast of the US. Upwelling along the coast brings up cold waters that have low pH and high dissolved inorganic carbon and CO2, which brings water that is undersaturated with respect to aragonite close to the surface.

9. Impact on oyster hatcheries in the Pacific Northwest
Taylor Shellfish Hatchery,
Dabob Bay, WA
Whiskey Creek Hatchery,
Netarts Bay, OR
Barton et al., 2012
WA Blue Ribbon Panel Report

10. Future projections IPCC AR5 SPM.7 RCP 8.5 (high future emissions)
RCP 2.6 (low future emissions)
IPCC AR5 SPM.8