Highlights Overarching WP 2Short term Assessment of CO2 air-sea fluxes

Brings together results from WPs 4, 5, 6, 12, 13, 14, 15 and 19.

•Observations:• Atlantic Carbon Observing Network • Surface water pCO2 for the Arctic, Atlantic and Southern Oceans, the North Sea, and the Mediterranean Sea.• Atmospheric CO2 and O2 at 4 sites.• CarboOcean data base

•Critical evaluation of interpolation methods•Seasonal and annual CO2 air-sea flux estimates•Long term trends in fluxes •Importance of sea ice for CO2 air-sea fluxes•Input to the Surface Ocean CO2 Atlas (SOCAT)•Several PhD theses

CO2 air-sea flux

= K • (fCO2water - fCO2air)

turbulence temperature, (temperature) biology, mixing,

circulation. wind speed, sea state

(@Assmy – AWI; Young - Natural History Museum)

fCO2 = γ x pCO2

(Pg C /yr)Global oceans (1990s, 2000-05)0 2.2±0.5 (0.94M pCO2 data)1 1.65 (3.0M pCO2 data)1 1.42 South of 50°S(0.94 M pCO2 data)1 0.4 (3.0 M pCO2 data)1 0.06

Pg = 1015 g (0Denman et al., 2007; 1Takahashi et al., 2009)

(Takahashi et al., 2009)

• • High pCO2 at ice edge

(Takahashi et al., 2009)

Importance of good data coverage & Input to global flux climatology

An Atlantic carbon observing network

Started 2002 (CAVASSOO), operational 2005 onwards

CarboOcean data base: Storage of surface water fCO2

Data collected duringCarboOcean, e.g.:• Atlantic Observing System• Southern Ocean (ships & buoys)

ALL data submitted by the CarboOcean PIs

@ Benjamin Pfeil, CarboOcean data manager

Telszewski et al., 2009. BG 6: 1405-1421.

Monthly surface water pCO2 for 2004, 2005 & 2006

• Interpolation of surface water pCO2 measurements with a neural network approach.

• First monthly pCO2 maps for the North Atlantic Ocean

• Flux maps have been created from the pCO2 maps.

Long-term changes in North Atlantic CO2 air-sea fluxes

(Schuster et al., 2009. DSR II 56: 620-629)

• A decrease in oceanic CO2 uptake for the northern North Atlantic (negative values).

• Little change in the CO2 sink in the western subtropical Atlantic.

Change in the annual meansea-air flux from 1990 to 2006

(mol m-2 yr-1)

Correlation of CO2 air-sea fluxes with the North Atlantic Oscillation (NAO)

(45-60N, W of 30W)

(>60N)

NAO+ (e.g. 1989-1995)• Strong winds• Strong North Atlantic Current and Labrador Current• More saline subtropical water reaches the eastern subpolar gyre and the polar seas.• Strong MOC in the Labrador Sea• Strong CO2 sink by strong NAC in northeastern North Atlantic (Thomas et al., 2008; GBC 22: GB4027)

•Strong correlation between CO2 air-sea flux and NAO for a 1-3 year lag.•The NAO-response of CO2 fluxes in different regions may be opposite.•Large decadal variation of the North Atlantic CO2 flux.(Raynaud et al., 2006; Ocean Science 2: 43-60)

Seasonal & interannual pCO2 changes in the North Sea

Omar et al. (2009) Ocean Science Discussions 6: 1655-1686.

ΔpCO2 (water-air) (µatm)

North-South transect

• The North Sea is an annual CO2 sink• Large interannual variation in CO2 air-sea fluxes.

Multi-annual variation in North Sea ΔpCO2

• ΔpCO2(w-a) increased (less negative) in August for 2001- 2005. (Thomas et al., 2007. GBC 21: GB4001)

ΔpCO2 in 08/2005 Change in ΔpCO2

Contribution to a revised mass balance of carbon on the continental shelves

Continental shelves act as sinks of 0.33-0.36 Pg C yr-1.Near-shore ecosystems act as sources of ~0.50 Pg C yr-1.(Chen and Borges, 2009)

Two tropical time-series stations

• Oceanic source of CO2 throughout the year.

• Seasonal & interannual variation of flux (Lefèvre et al.)

• at 6°S, 10°W since June 2006 • at 8°N, 38°W since April 2008 • hourly measurements of surface fCO2

Monthly CO2 flux at 6oS, 10oW

Monitoring fCO2 with CARIOCA drifters

Ocean CO2 sinks of • 0.8 Pg C yr-1 in the Subantarctic Zone • <0.1 Pg C yr-1 in the Polar Zonefrom CARIOCA data since 2001. Boutin et al. (2008) L&O 53: 2062-2079.

SAF

PF

6

sourcenkfCO2(water -air) (µatm)

oceanic sink

A reduction in CO2 uptake in the Southern Ocean?

The overall trend of 2.11 (±0.07) µatm yr-1 suggests that surface water fCO2 increased faster than atmospheric fCO2 by about 0.4 µatm yr-1.

Metzl, 2009, DSR II 56:607-619. Also Le Quéré et al., 2007. Science 316:1735-1738.

Atmospheric fCO2

Annual increase of surface water fCO2 for 1991 to 2007 in the SW Indian Ocean

A decrease in ozone (O3) may reduce Southern Ocean CO2 uptake by strengthening the winds

Lenton et al., GRL, 2009: GRL 36: LI2606

Importance of sea ice for CO2 air-sea fluxes (Arctic & Southern Ocean)

Brown ice, 17-20/12/02

Below ice: fCO2(w-a) 0 to 40 µatmUpon melt: fCO2(w-a) -50 to 0 µatm

Biological carbon uptake rapidly creates a CO2 sink during and upon ice melt in the Weddell Sea.

08-10/12/2004

20/12/2004

0°W Surface fCO2 decrease during ice melt

17/12/2004

(%)

Sea ice coverage

Bakker et al. (2008) BG 5: 1373-1386; alsoAnderson et al. (in press) GRL.

Initiated in 2007 by IOCCP, SOLAS, IMBER; http://www.ioccp.org/

Aims:• 2nd level quality controlled (QC) global surface ocean fCO2 data set• Gridded global SOCAT product of monthly surface water fCO2 means, with no temporal or spatial interpolation (i.e. bin averages). • The data products will be made publicly available.

Input to SOCAT (Surface Ocean CO2 Atlas)

Input to SOCAT (Surface Ocean CO2 Atlas)

• Public fCO2 data in common format (Pfeil, Olsen, UoB).• Life Access Server for data access (Hankin, Malzcyk, PMEL).•2nd level QC by regional groups (coastal, Pacific, Atlantic, Indian, Southern Oceans).• SOCAT product release (mid 2010)• SOCAT data synthesis & scientific articles• Joint SOCAT & ocean interior science meeting, spring 2011.

• SOCAT synthesis & output for IPCC AR5? (spring 2011)• SOCAT input to RECCAP? (RECCAP synthesis by 03/2011).

Highlights Overarching WP 2Short term Assessment of CO2 air-sea fluxes

Brings together results from WPs 4, 5, 6, 12, 13, 14, 15 and 19.

•Observations:• Atlantic Carbon Observing Network • Surface water pCO2 for the Arctic, Atlantic and Southern Oceans, the North Sea, and the Mediterranean Sea.• Atmospheric CO2 and O2 at 4 sites.• CarboOcean data base

•Critical evaluation of interpolation methods•Seasonal and annual CO2 air-sea flux estimates•Long term trends in fluxes •Importance of sea ice for CO2 air-sea fluxes•Input to the Surface Ocean CO2 Atlas (SOCAT)•Several PhD theses.

Surface water fCO2 data collection and storage

Data collected duringCarboOcean, e.g.:• Atlantic Observing System• Southern Ocean (ships & buoys)

Historic data submitted by PIs from the:• Nordic Seas• North Sea• Atlantic Ocean• Southern Ocean

@ Benjamin Pfeil, CarboOcean data manager