Ocean Acidification Lecture

Hilary Palevskypalevsky@uw.edu

Absorbing CO2 changes ocean pH

IPCC AR5, Figure SPM.4

Hawaii (Mauna Loa)South Pole

Hawaii (ALOHA)Bermuda (BATS)Canary Is. (ESTOC)

Gary Braasch Photographyhttp://www.worldviewofglobalwarming.org

Gary Braasch Photographyhttp://www.worldviewofglobalwarming.org

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+]

Ocean carbonate chemistry

CO2 dissolution in water:

CO2 + H2O ↔ H2CO3

H2CO3 ↔ H+ + HCO3-

HCO3- ↔ H + + CO3

2-

Forming CaCO3 shells:

Ca2+ + CO32- ↔ CaCO3

Ω = [Ca2+][CO32-]/KspWhen Ω < 1, water is undersaturated and CaCO3 will

dissolve

Calcifying organismsGeoduck Blue mussel

Urchins

Pink calcifying algae

Juvenile king crabDungeness 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

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)

Pteropods dissolve in water with pH and carbonate chemistry expected for 2100

OA in the California Current System

Gruber et al., 2012

OA in the California Current SystemFeely et al., 2008

Impact on oyster hatcheries in the Pacific Northwest

Barton et al., 2012 WA Blue Ribbon Panel Report

Taylor Shellfish Hatchery,Dabob Bay, WA

Whiskey Creek Hatchery,Netarts Bay, OR

IPCC AR5 SPM.7

IPCC AR5 SPM.8

RCP 2.6 (low future emissions)

RCP 8.5 (high future

emissions)

Future projections