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