oceanic carbon cycle

Vulnerability of the ocean

biological pump

Corinne Le Quéré

University of East Anglia and British Antarctic

Survey

oceanic carbon cycle

45

34

physical transport

11

33

CO2

CO2 + H2O + CO2-3 2HCO-

3

chemical reactions

90

numbers in PgC/yr

biological activity

11

atmosphere

ocean

surface

mixed layer depth

atmosphere

100 m

biological activity

real surface

atmosphere

100 m

biological activity

Ecosystem composition

Export

11 PgC/y

Respiration

34 PgC/y

Primary Production

45 PgC/y

pico-heterotrophsbacteria

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producers

mixed

silicifiers

zoo-plankton

proto

meso

macro

what controls export?

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

Primary Production

45 PgC/y

what they do

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

what they do

these bloom

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

what they do

these form shells

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

what they do

these respond to

pH

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

what they do

these float

phyto-plankton

pico-autotrophs

N2-fixers

calcifiers

DMS-producersmixed

silicifiers

what they need

Fe P N

Fe P N

Fe P NFe P NFe P N

Fe P N Si

Respiration

34 PgC/ypico-heterotrophsbacteria

zoo-plankton

proto

meso

macro

what they do

pico-heterotrophsbacteria

zoo-plankton

proto

meso

macro

what they do

these control blooms

pico-heterotrophsbacteria

zoo-plankton

proto

meso

macro

what they do

these produce big

feacal pellets

pico-heterotrophsbacteria

zoo-plankton

proto

meso

macro

what they need

F O O D

F O O D

F O O D

F O O D

time scale

phytoplankton turnover time:

1 week

bacterial respiration:

1 day

sinking rate:

50 m/day

zooplankton turnover time:

1-many weeks

time scale

a few +1 days

a few days

pico-heterotrophspico-heterotrophs

phyto-phyto-planktonplankton

zoo-zoo-planktonplankton

pico-autotrophspico-autotrophs

NN22-fixers-fixers

calcifierscalcifiers

DMS-producersDMS-producersmixedmixed

silicifierssilicifiers

bacteriabacteria

protoproto

mesomeso

macromacro

HOT SPOTS:HOT SPOTS:

Export

11 PgC/y

Respiration

34 PgC/y

Primary Production

45 PgC/yQQ1010=1.9=1.9

QQ1010=2.2=2.2

QQ1010=3.0=3.0

TEMPERATURE RESPONSETEMPERATURE RESPONSE

pico-heterotrophspico-heterotrophs

phyto-phyto-planktonplankton

zoo-zoo-planktonplankton

pico-autotrophspico-autotrophs

NN22-fixers-fixers

reduced ballast reduced ballast

DMS-producersDMS-producersmixedmixed

silicifierssilicifiers

bacteriabacteria

protoproto

mesomeso

macromacro

HOT SPOTS:HOT SPOTS:

Export

11 PgC/y

Respiration

34 PgC/y

Primary Production

45 PgC/y

pH RESPONSEpH RESPONSE

pico-heterotrophspico-heterotrophs

phyto-phyto-planktonplankton

zoo-zoo-planktonplankton

pico-autotrophspico-autotrophs

NN22-fixers-fixers

calcifierscalcifiers

DMS-producersDMS-producersmixedmixed

silicifierssilicifiers

bacteriabacteria

protoproto

mesomeso

macromacro

HOT SPOTS:HOT SPOTS:

Export

11 PgC/y

Respiration

34 PgC/y

Primary Production

45 PgC/y

RESPONSE TO STRATIFICATIONRESPONSE TO STRATIFICATION

??

oceanic carbon cycle

45

34

physical transport

11

33

CO2

CO2 + H2O + CO2-3 2HCO-

3

chemical reactions

90

numbers in PgC/yr

biological activity

11

atmosphere

ocean

CO2 sink (PgC/y)Exp

ort

(P

gC

/y)

410

14

0

in one decade

what controls export?

the ecosystem compositionand

the physical transport

what controls export in models?

the ecosystem composition=

the physical transport

models

PhytoPO4

DOC Zoo

POC

export

air-sea fluxes

CLI MATE RES PONSE O F OCEAN IC UPTAKE

Sarmientoet al. (1998)

Matear andHirst (1999)

J oos et al.(1999)

T ime Span 1990-2065 1850-2100 1765-2100

Warm ing Eff ect -11% -12% -13%

Anthropogenic Effect -22% -10% -3%

Biological Pump +24% +8% +6%

TOTA L -9% -14% -10%

(slide adapted from J. Sarmiento)

observations?

Global changes in Atmospheric Potential Oxygen

models only

Global changes in Atmospheric Potential Oxygen

Slide not available because the data is not published. APO data shows at least 2x more

variability than the models.

NPZD

DGOM

Interannual chla variability (mgChl/m3)

PISCES-T

Observations (SeaWiFS)

Calcifiers

PO

4

Fe

PO4

DOC Zoo

POC

export

NPZD

DGOM

Interannual chla variability (percent)

PISCES-T

Observations (SeaWiFS)

model projection of climate change in 2060

temperature

ice cover

mixed layer depth

Impact of climate change on the CO2 sink in 2060 (mol/m2/y)

Calcifiers

PO

4

Fe

(Preliminary result from E. T. Buitenhuis)

what comes now?

truth(what is the vulnerabilit

y of the marine

biological pump?)

illusion

time

evolution of model results

time

chaos

illusion

evolution of model results

truth(what is the vulnerabilit

y of the marine

biological pump?)

illusion chaos

relief

time

evolution of model resultsocean

biogeochemistry models

truth(what is the vulnerabilit

y of the marine

biological pump?)

thanks to Erik T. Buitenhuis and Olivier Aumont for providing model codes and results