Long-lived greenhouse gases: air-sea exchange and impact
Dorothee Bakker, Peter Landschtzer 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 contributors;
@Sebastian Hennige Co-authors COST chapter : Hermann Bange, Alberto
Borges, Bruno Delille, Nicolas Gruber, Truls Johannessen, Carolin
Lscher, Wajih Naqvi, Abdirahman Omar, Magdalena Santana-Casiano,
Rob Upstill-Goddard Slide 2 Rapid increase in atmospheric content
of long-lived greenhouse gases Forster et al. 2007. IPCC Carbon
Dioxide (CO 2 ) Slide 3 GHG Radiative forcing 2005 (W/m 2 )
Atmosphe- ric lifetime (years) Air-sea exchangeImpact & Future
Change CO 2 1.66[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? N2ON2O0.16112
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 4 0.4814
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) Slide 4 Oceanic N 2 O production by
denitrification and nitrification (Suntharalingam and Sarmiento
2000) Arabian Sea 19 N 67 E (Naqvi 2008) Slide 5 Upper ocean CH 4
production Krey et al 2009 Forster et al. 2009 DSR2 (56): 964-976
Slide 6 CH 4 hydrates & CH 4 bubbles (Krey et al 2009)
Recovered CH 4 hydrate Expected CH 4 hydrate Large uncertainty CH 4
hydrate inventory (OConnor 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). Slide 7 (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 fCO 2 (water-air) fCO 2 = pCO 2, ~ 0.997. Slide 8 (Schuster
and Watson, JGR, 2007, doi:10.1029/2006JC003941) Latitude [ o N]
Air-to-sea flux CO 2 [mol m -2 year -1 ] 25303540455055 0 1 2 3
Average 1994/95 Average 2002/05 1994/95 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 Slide 9 Year-to-year variation in North Atlantic
CO 2 sink Watson et al. 2009 Science 326:1391-1393. Slide 10 A
North Atlantic pCO 2 observing network on VOS 2002-2004 (Cavassoo),
2005-2009 (CarboOcean), 2011-2014 (CarboChange), ICOS? Slide 11
Version 1.5 www.socat.info v1.5 public 14/09/11 Slide 12 6.3
million fCO 2 on 1851 cruises from 1968 to 2007. 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) www.socat.info Slide 13 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) www.socat.info (Bakker et al. (2012) Eos 93(12): 125-126;
Pfeil et al., in prep.; Sabine et al., in prep.; Left figure by
Reiner Schlitzer AWI. Slide 14 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:
1405-1421)
