Long-lived greenhouse gases: air-sea exchange and impact Dorothee Bakker, Peter Landschützer Ute Schuster, Andrew Watson Roughly 90 SOCAT scientists and data contributors! Benjamin Pfeil, Are Olsen, Jeremy Malczyk, Heather Koyuk, Steven Hankin, Dorothee Bakker, Chris Sabine, Denis Pierrot, Nicolas Metzl, Ansley Manke, Alex Kozyr, Reiner Sieger, Maria Hood, Kathy Tedesco, Maciej Telszewski, and all other SOCAT scientists and data Hennige Co-authors COST chapter : Hermann Bange, Alberto Borges, Bruno Delille, Nicolas Gruber, Truls Johannessen, Carolin Löscher, Wajih Naqvi, Abdirahman Omar, Magdalena Santana-Casiano, Rob Upstill-Goddard

Rapid increase in atmospheric content of long-lived greenhouse gases Forster et al IPCC Carbon Dioxide (CO 2 )

GHG Radiative forcing 2005 (W/m 2 ) Atmosphe- ric lifetime (years) Air-sea exchangeImpact & Future Change CO [100, f(ocean sink)] Net ocean CO 2 sink for 30% anthropogenic emissions; Ocean ultimately controls atmospheric CO 2 content. Partial mitigation of climate change; Ocean acidification affects marine biota; Medium to long-term ocean sink? N2ON2O Natural oceanic (20%) & anthropogenic coastal (10%) N 2 O source; Other processes dominate atmospheric N 2 O content. Removal stratospheric O 3 ; Oceanic deoxygenation small effect. CH Small natural oceanic and coastal CH 4 source (10%); Continental CH 4 seeps poorly quantified; Other processes dominate atmospheric CH 4 content (land sources, lifetime). Regulates tropospheric O 3 & OH radical; Increased release from CH 4 hydrates in warmer ocean (CO 2 ↑); Oceanic deoxygenation small effect. (IPCC, 2007; COST chapter, in review)

Oceanic N 2 O production by denitrification and nitrification (Suntharalingam and Sarmiento 2000) Arabian Sea 19 ° N 67 ° E (Naqvi 2008)

Upper ocean CH 4 production Krey et al 2009 Forster et al DSR2 (56):

CH 4 hydrates & CH 4 bubbles (Krey et al 2009) Recovered CH 4 hydrate Expected CH 4 hydrate Large uncertainty CH 4 hydrate inventory (O’Connor et al. 2010) ; CH 4 hydrates melt upon warming (Arctic Ocean!); ~90% of CH 4 released is oxidized to CO 2 in water column; Potential large short-lived effect from added GHG CH 4 (Archer 2007); Long-term effect (>1,000 years) from added CO 2 GHG of similar magnitude as CO 2 from fossil fuel use (Archer and Buffet 2005).

(IPCC, 2007) Impact of oceanic CO 2 uptake Net oceanic CO 2 uptake reduces anthropogenic climate change. Oceanic CO 2 uptake reduces pH, [CO 3 2- ] and calcification, i.e. leads to ocean acidification. CO 2 air-sea flux = k K 0 ΔfCO 2 (water-air) fCO 2 = γ pCO 2, γ ~

(Schuster and Watson, JGR, 2007, doi: /2006JC003941) Latitude [ o N] Air-to-sea flux CO 2 [mol m -2 year -1 ] Average 1994/95 Average 2002/ /95 with 2002/05 temperature 2002/05 with 1994/95 wind speed Decadal variation or long-term trend? A decrease in the North Atlantic CO 2 sink from 1994/95 to 2002/05 CO 2 sink

Year-to-year variation in North Atlantic CO 2 sink Watson et al Science 326:

A North Atlantic pCO 2 observing network on VOS (Cavassoo), (CarboOcean), (CarboChange), ICOS?

Version v1.5 public 14/09/11

6.3 million fCO 2 on 1851 cruises from 1968 to fCO 2 in uniform format with 2 nd level quality control. Transparent, fully documented. Public with regular updates planned. Surface Ocean fCO 2 (v1.5)

Data products 1) Global surface ocean data set of recalculated fCO 2 in a uniform format with 2nd level quality control; 2) Individual cruise files of recalculated fCO 2 (as 1); 3) Global gridded product of monthly surface water fCO 2 means, with minimum interpolation. January average (all years) (Bakker et al. (2012) Eos 93(12): ; Pfeil et al., in prep.; Sabine et al., in prep.; Left figure by Reiner Schlitzer – AWI.

Spot pCO 2 data CO 2 mapping Satellite SST, chl & winds help interpolate the network pCO 2 data accurately, to create maps. CO 2 measurement network (Slide courtesy of Andrew Watson; Telszewski et al. (2009) BG 6: )