Global Carbon Cycle

Sabine et al. (2004) SCOPE

•Ocean sequester ~30% of fossil fuel CO2

•Human perturbations overlay large natural background C cycle•Climate responses and feedbacks of ocean C sink not well known

Feb 2004 Chemical Oceanography SeminarFeb 2004 Chemical Oceanography Seminar

3

4

Average Surface Water DIC Increase in 2000 ~ 1.2 µmol kg-1 yr-1

Under IPCC “Business as Usual”the pH of surface sea water drops by 0.4 pH units by 2100. CO3

= in surface water drops by 54% from pre-industrial values.

2004 Hatfield Seminar2004 Hatfield Seminar

= [Ca2+][CO3

2-] Ksp'a > 1 ~ Supersaturated

Air Increase = 1.48 ± 0.05 µatm yrAir Increase = 1.48 ± 0.05 µatm yr-1-1; Seawater Increase = 2.48 ± 0.28 ; Seawater Increase = 2.48 ± 0.28 µatm yrµatm yr-1-1

Dore et al., (2003)Dore et al., (2003)

WOCE/JGOFS/OACES Global CO2 Survey

~72,000 sample locations collected in the 1990s

DIC ± 2 µmol kg-1

TA ± 4 µmol kg-1Sabine et al (2004).

Because the ocean Because the ocean mixes slowly, half of mixes slowly, half of the anthropogenic the anthropogenic COCO22 stored in the stored in the oceans is found in oceans is found in the upper 10% of the upper 10% of the ocean.the ocean.

Sabine et al. Science (2004)

Global Global Anthropogenic Anthropogenic COCO22 Inventory = Inventory = 118±19 Pg C118±19 Pg C

Column inventory of anthropogenic COColumn inventory of anthropogenic CO2 2 that has that has accumulated in the ocean between 1800 and 1994 (mol maccumulated in the ocean between 1800 and 1994 (mol m-2-2))

Mapped Inventory 106±17 Pg C+ marginal seas 6± 6 Pg C

+ Arctic Ocean 6± 6 Pg C

Total Inventory 118±19 Pg C Sabine et al. Science (2004)

Over the past Over the past 200 years, the 200 years, the ocean has been ocean has been the only the only reservoir to reservoir to consistently take consistently take up up anthropogenic anthropogenic COCO22 from the from the atmosphere.atmosphere.

Carbon Changes Between 1800 and Carbon Changes Between 1800 and 19941994

Sabine et al. Science (2004)

Aragonite and Calcite Saturation Depths in the Global Oceans

From Riebesell et al. Nature (2001)From Riebesell et al. Nature (2001)

Scanning electron micrographs of Emiliania huxleyi (left) and Scanning electron micrographs of Emiliania huxleyi (left) and Geophyrocapsa oceanica (right) under conditions of 300 (top) Geophyrocapsa oceanica (right) under conditions of 300 (top) and 780 - 850 ppm (bottom) pCOand 780 - 850 ppm (bottom) pCO22 showing malformed showing malformed coccospheres at the higher COcoccospheres at the higher CO22 levels. levels.

2004 Hatfield Seminar2004 Hatfield Seminar

Coccolithophorescalcite

Corals

NOAA

Forams

Calcareous algae

Nancy Sefton

T. Tyrrel

calcite

High-Mg calcite

aragonite

2004 Hatfield Seminar

Pteropods

Clio pyramidata

Victoria J. Fabry

R. W. Gilmer and G. R. Harbison

Cavolinia tridentata

aragonite aragonite

R. W. Gilmer and G. R. Harbison

The effects of increased levels of CO2 on the dissolution of Clio pyramidata shells after 4 and 48 hours of exposure.

2004 Hatfield Seminar

From: R. Buddemeier

From: R. Buddemeier

From: R. Buddemeier