Impact of climate change on the
global oceanic sink of CO2
Corinne Le Quéré,
University of East Anglia and
British Antarctic Survey
Smith and Reynolds 2005 and IPCC 2007
water
energy
observed warming trend 1979-2005
decadal changes in the earth’s physical system
winds
geological reservoirs
fossil fuel emissions land use
changeland sink
ocean sink
7.2 1.5 2.3
2.2
atmosphere
4.2
2000-2005 CO2 budget (GtC/y)
Global Carbon Project, Canadell et al. 2007
decadal trend in the Airborne Fraction
atm CO2
CO2 emissions (FF + Land Use)
gain of 0.053(p = 0.89)
1960 1970 1980 1990 2000
time
Air
born
e f
ract
ion
Canadell et al. 2007, PNAS
geological reservoirs
fossil fuel emissions land use
changeland sink
ocean sink
7.2 1.5 2.3
2.2
atmosphere
4.2
2000-2005 CO2 budget (GtC/y)
Global Carbon Project, Canadell et al. 2007
physical transport
CO2
chemical reactions
atmosphere
ocean
biological activity
Mauna Loa observatory (Hawaii)
Alert (Canada)
Palmer (Antarctica)
Alert (Canada)
Palmer (Antarctica)
atmospheric CO2
time (y)
Alert (Canada)
Palmer (Antarctica)
atmospheric CO2
Atmospheric Inverse Model:
Cmeasured ↔ Cmodeled = Af +co
model and approach: Christian Rödenbeck
CO2 sink
(PgC/y)
expected trend
Le Quéré, Rödenbeck, Buitenhuis et al. 2007
change in Southern Ocean CO2 sink
data from Takahashi et al., DSR (2008)
Feely et al., 2006, Schuster and Watson, 2007, Takahashi et al., 2006
deseasonalised observations, evenly distributed over 3 decades
longest data series from: Richard Feely, Cathy E. Cosca, Rik Wanninkhof, David W. Chipman, Colm Sweeney, Andrew Watson, Dorothee C. E. Bakker, Ute Schuster, H. Yoshikawa-Inoue, Masao Ishii and T. Modorikawa, Y. Nojiri, Jon
Olafsson, C. S. Wong., Arne Kroetzinger, Bronte Tilbrook, Truls Johannessen and Are Olsen.
trend in oceanic pCO2 1981-2007 (uatm/y)
1.6
0.4
2.8
data from Takahashi et al., DSR (2008)
Feely et al., 2006, Schuster and Watson, 2007, Takahashi et al., 2006
deseasonalised observations, evenly distributed over 3 decades
longest data series from: Richard Feely, Cathy E. Cosca, Rik Wanninkhof, David W. Chipman, Colm Sweeney, Andrew Watson, Dorothee C. E. Bakker, Ute Schuster, H. Yoshikawa-Inoue, Masao Ishii and T. Modorikawa, Y. Nojiri, Jon
Olafsson, C. S. Wong., Arne Kroetzinger, Bronte Tilbrook, Truls Johannessen and Are Olsen.
trend in oceanic pCO2 1981-2007 (uatm/y)
1.6
0.4
2.8
• PISCES-T ecosystem model • 2 phyto, 2 zoo., 2 sinking particles• limitation by Fe, P, and Si• initialise with observations in 1948
(Buitenhuis et al., GBC 2006)
identifying the processes with the OPA model
• OPA General Circulation model • 0.5-1.5ox2o resolution• 31 vertical levels • calculated vertical mixing• NCEP daily forcing
SSMI winds (Wentz et al 2007)updated from Reynolds and Smith (1994)
Obs
NCEP
NCEP2
Trends
1982-2007 SST 1988-2007 winds
+1°C
+0.4 m/s
Obs
CO2 only
Trends in ocean pCO2 (uatm/y)
Le Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
Obs
NCEP
NCEP2
Trends in ocean pCO2 (uatm/y)
Le Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
CO2 and climate
CO2 sink
(PgC/y)
CO2 only
Time (y)
change in Global Ocean CO2 sink
Le Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
CO2 and climate
Atmospheric inversion
Ocean model
CO2 and climate CO2 only
globe- 0.09 ±
0.190.12 0.32
north 0.04 ± 0.04 0.05 0.05
tropics- 0.13 ±
0.130.01 0.14
south- 0.01 ±
0.050.06 0.13
Trend in ocean CO2 sink (PgC/y per decade, 1981-2007)
difference of 0.20
PgC/y per decade
Le Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
• PISCES-T ecosystem model • 2 phyto, 2 zoo., 2 sinking particles• limitation by Fe, P, and Si• initialise with observations in 1948
(Buitenhuis et al., GBC 2006)
identifying the processes with the OPA model
• OPA General Circulation model • 0.5-1.5ox2o resolution• 31 vertical levels • calculated vertical mixing• NCEP daily forcing
• no T effect on CO2
• constant fluxes
Le Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
Climate only
combined temp wind fluxes
globe -0.20 -0.04 -0.17 -0.03
north -0.01 -0.03 -0.01 0.01
tropics -0.13 -0.01 -0.10 -0.03
south -0.06 -0.01 -0.06 -0.01
Trend in ocean CO2 sink (PgC/y per decade, 1981-2007)
~50% of recent trends in ocean CO2 sink
can be attributed to human activitiesLe Quéré, Takahashi, Buitenhuis, Rödenbeck & Sutherland, in prep.
the Airborne Fraction
atm CO2
CO2 emissions (FF + Land Use)
(p = 0.89)
1960 1970 1980 1990 2000
time
Air
born
e f
ract
ion
Canadell et al. 2007, PNAStrend in airborne fraction: 0.07 PgC/y per decade
trend in ocean CO2 sink from climate (since 1981): 0.20 PgC/y per decade
modelled change in carbon storage (μmol/L)
1000
2000
3000
4000
depth (m)
modelled change in surface pH
1000
2000
3000
4000
depth (m)
-0.05
0
1981-2004 conditions
deep ocean
Cdeep = 2260
Csurface = 2120
higher winds causes CO2
outgassing
human CO2 emissions
65ºS 35ºS
conditions under very high atmospheric CO2
deep ocean
Cdeep = 2260
Csurface > 2260
human CO2 emissions higher winds
causes CO2
uptake
65ºS 35ºS
>100 years after CO2 emissions stop
deep ocean
Cdeep = 2260 + C
Csurface = 2120 + C
higher winds causes CO2
outgassing
65ºS 35ºS
Raupach et al., 2007
fossil fuel CO2 emissions for the world
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