1. Determining the magnitude and variability of the anthropogenic CO 2 uptake rate by the oceans. Dick Feely (NOAA/PMEL/JISAO) Chris Sabine (NOAA/PMEL/JISAO) Rolf Sonnerup (JISAO/PMEL) Paul Quay (UW/JISAO)

2. JISAO/PMEL/UW Collaboration Observational Program (Feely, Sabine, Quay) –Measuring pCO 2, dissolved inorganic carbon (DIC), alkalinity, 13 C/ 12 C of DIC (δ 13 C) –Using research cruises, volunteer observing ships (VOS), and moorings Modeling Program (Sonnerup) –Using GCMs to simulate anthropogenic CO 2, 13 C/ 12 C perturbations

3. Estimates of Global CO 2 Sources & Sinks ___________________________________________ ____________________________________________

4. Scientific Objectives Estimate the rate of increase in the amount of anthropogenic CO 2 in the ocean. (research cruises) Estimate the net air-sea flux of CO 2. (VOS+moorings) Determine whether the US coastal ocean is a source or sink for CO 2. (research cruises + moorings) Separate natural variations from anthropogenic change in ocean CO 2. (data synthesis + models) Determine how changes in physical, chemical and biological processes affect the CO 2 uptake rate. (models)

5. CLIVAR/CO 2 Repeat Hydrography Program We mus understand the temporal and spatial changes of the global ocean carbon system and the feedbacks to the climate system. We mus understand the temporal and spatial changes of the global ocean carbon system and the feedbacks to the climate system.

6. VOS Cruise Tracks (IOCCP)

7. Space and time coverage of ocean carbon observing networks time space 1 m 2 1 km 2 Globe Ocean Basin Regional (10 6 km 2 ) centuries decadal Inter-annual seasonal daily Remote sensing hourly Process Studies Repeat Trans-basin Sections VOS surface pCO 2 Shipboard Time- Series Moored Time-Series time space 1 m 2 1 km 2 Globe Ocean Basin Regional (10 6 km 2 ) centuries decadal Inter-annual seasonal daily Remote sensing hourly Process Studies Repeat Trans-basin Sections VOS surface pCO 2 Shipboard Time- Series Moored Time-Series

8. Rate of CO 2 Increase Atmospheric CO 2 is currently at 375 ppm (vs pre- industrial 280 ppm) and has been increasing by about 2 ppm per year over the last decade. Surface ocean in equilibrium with atmosphere would increase CO 2 by 10 μmole/kg per decade. ~ 0.5% of background DIC concentration.

9. Rate of 13 C/ 12 C (δ 13 C) decrease The δ 13 C of atmospheric CO 2 today is –8.1 ‰ (versus –6.4 ‰ in pre-industrial era) and decreasing at 0.2 ‰ per decade. - δ 13 C of CO 2 from fossil fuel combustion is -28 ‰. Surface ocean δ 13 C in equilibrium with atmosphere would decrease at 0.2 ‰ per decade. The magnitude of oceanic δ 13 C decrease is proportional to anthropogenic CO 2 uptake.

10. Because the ocean mixes slowly, half of the anthropogenic CO 2 stored in the ocean is found in the upper 10% of the ocean. Average penetration depth 1000 m 50% of anthropogenic CO 2 in the ocean is shallower than 400 m

12. Seasonal and interannual changes in DIC and δ 13 C at Stn ALOHA (23°N 153°W)

13. Princeton MOM vs Observations

14. Changes in DIC and δ 13 C between 1993 and 2003 in the N. Atlantic (Repeat of A16N)

15. GCM Simulated  13 C Change (2003-1993) (‰)