Causes, Time Scales and Consequences

François M. M. Morel

Slides by Ja-Myung Kim

Years before 2010

330 µatm

400 µatm

Vostok paleo

Petit et al. 1999 , Keeling et al.

Mauna Loa

from ice core & modern data

Changes in atm. CO2 concentrationpC

O2 (

µatm

)

400 µatm

Seawater pCO2 time-series monitoring stn.

ESTOC(1995-2009)

BATS(1983-2009)

ALOHA(1988-2009)

Decadal changes at time-series stations

ESTOC(1995-2009)

BATS(1983-2009)

ALOHA(1988-2009)

400

350

300

250

200

1985 1990 1995 2000 2005 2010

Year

pCO

2 (µa

tm)

ALOHA(1988-2009)

ESTOC(1995-2009)

Bates NR, Byrne RH, Dore JE, Feely RA, Gonzalez-Davila M, Karl DM, Lee K, Kleypas JA, Orr J (IPCC ARS)

400

350

300

250

200

1985 1990 1995 2000 2005 2010

Year

pCO

2 (µa

tm)

BATS(1983-2009)

pCO2 increase = 1.5 - 1.8 μatm yr-1

400

350

300

250

200

1985 1990 1995 2000 2005 2010

Year

pCO

2 (µa

tm)

Atlantic0

1000

2000

3000

Pres

sure

(db)

60° 50° 40° 30° 20° 10° 0° 10° 50° 60° N40°30°20°

Indian Pacific0

1000

2000

3000

Pres

sure

(db)

60° 50° 40° 30° 20° 10° 0° 10° 50°40°30°20°60° 50° 40° 30° 20° 10° 0° 10° 20°

Latitude

0

1000

2000

3000

Pres

sure

(db)

Latitude

Vertical distributions of CO2 in the ocean

Anthropogenic CO2 conc. (μmol kg-1)

50403020100

“Half of the CO2 stored in the oceans is found in the upper

10% of the ocean”

Sabine et al. 2004

Anthropogenic carbon emissions are increasing atmospheric CO2

Ocean is a CO2 sink

Why and Howdoes that affect ocean chemistry ?

Ocean acidification

CO2 (aq)

HCO3- CO3

2-

+ H2O + HCO3-H+

CO2 (aq)CO2 (g)

Effect of CO2 on carbonate system

H+ +

CO2 increases CO3

2- decreasesH+ increases (pH decreases)

ESTOC(1995-2009)

BATS(1983-2009)

ALOHA(1988-2009)

Decadal changes of pH & CO32-

at time-series monitoring stn.pH decrease: 0.0013 - 0.0018 yr-1

CO32- decrease : 0.5 - 0.9 µmol kg-1 yr-1

CO32-

pH

CO2

CO32-

What biological consequences ?

Photosynthesis

CalcificationOther

physiologicaleffects

What biological consequences ?

Photosynthesis Calcification OtherPhysiological

effects

CO2 CO32- pH

Experimental approaches

Molecular mechanisms

Lab cultures

Coastal in-situ perturbation

Open ocean monitoring

Bottles

Big bags

Natural env.

Open ocean monitoring

Univ. of BergenUniv. of BergenUniv. of WashingtonUniv. of Washington

EPOCAEPOCA

POSTECHPOSTECH

Svalbard

Norway

South Korea

U.S.A

Mesocosm

Open ocean mesocosm, Baltic seaU. Riebesell (GEOMAR)

In situ ecosystem-based CO2 perturbation experiment

MESOCOSM

Laboratory cultures

Low CO2 High CO2

Mechanismstudy

What biological consequences ?

Photosynthesis Calcification OtherPhysiological

effects

CO2 CO32- pH

Photosynthesis

CH2OOrganic matter

Light reaction

Dark reactione-

photons

H2O

O2

CO2

Sediments

Atmosphere

Org C

Phytoplankton

SurfaceOcean

CO2

CO2

500

1000

1500

2000

Depth (m)

0 20 40 60

CO2 (µM)

Biological pump

Photosynthesis

Light reaction

Dark reaction

e-

H2O

O2

CO2

CH2Oorganic matter

RubisCO

Poor affinity for CO2 Km ≈ 50 µM

>> [CO2]seawater

Carbon concentrating mechanism

Chloroplast

CO2

80 µM

HCO3-HCO3

-

CO2CO2

10 µM

HCO3-

CA CA

CH2OCA

RubisCO

2 mM

CASkeletonema costatum

0

2000

CA

act

ivity

U (

mg

Chl

a)-1

1000

180 360 1800 ppm

Enzyme

Rost et al. 2003

Response of CCM to increasing CO2

Growth rates

Labculture

280 720 ppm

3.0

2.0

0

1.0

Gro

wth

rat

e (d

-1)

Skeletonema costatum

Rost et al. 2003

Growth rates

280 720 ppm

1.5

1.0

0

0.5

Gro

wth

rat

e (d

-1)

Skeletonema costatum

40%In-situ

Kim et al. 2006

Growth rates

100 800 ppm

Gro

wth

rat

e (d

-1) Natural assemblage

Ocean

2.0

1.0

0

0.5

1.5

Tortell et al. 2000

Growth rates

Low CO2 High CO2

Gro

wth

rat

e (d

-1) 2.0

1.0

0

0.5

1.5 ? Future growth rate

What biological consequences ?

Photosynthesis Calcification OtherPhysiological

effects

CO2 CO32- pH

Calcium carbonate (CaCO3)production & dissolution

Main overall reaction:

+Ca2+ CO32- CaCO3(s)

[CO32-] > [CO3

2-] sat

[CO32-] < [CO3

2-] sat

Calcite Aragonite

Future projection for saturation state

Turley et al. 2010

[CO32-] = [CO3

2-]sat

[CO32-] / [CO3

2-]sat Aragonite[CO3

2-] / [CO32-]sat Calcite

Tropical corals Coraline algae

Molluscs

Pteropods

Coccolithophores

Responses of marine calcifiersto increasing CO2

Mussels & Oysters

Gazeau et al. 2007

Mussels (Mytilus edulis)

Oysters (Crassostrea gigas)

Coccolithophores4.0

3.8

3.6

3.4

3.2Low CO3

2-

AmbientCO3

2-HighCO3

2-

Cocc

olith

size

(µm

) Coccolith

Engel et al. 2005

Adapted from Doney et al. 2009

Major groups

Tropical corals

Coraline red algae

Molluscs

Pteropods

Coccolithophores

Responses at increasing CO2

Different responses of marine calcifiersto increasing CO2

Poor understanding of the mechanisms responsible for the sensitivity

Seawater pH

Calc

ifyin

g p

H

8.5

8.0

7.57.0 7.5 8.0 8.5

Seawater

Skeleton

inside

H+

Ca2+ CaCO3CO32-+

HCO3- + H+CO3

2-

Seaw

ater

Venn et al. 2013

Stylophorapistillata

(reef coral)

What biological consequences ?

Photosynthesis OtherPhysiological

effects

CO2 pH

Calcification

CO32-

l all

pH homeostasis External enzymes

Metalavailability

Physiologicalprocesses

pH

l all

Physiologicalprocesses

pH

Metalavailability

Fe(OH)3 + H+

Fe

pH homeostasis External enzymes

Photosynthesis

Light reaction

Dark reactione-

H2O

O2

CO2

Fe

Organic matter

Effect of pH on Fe chemistry

Ca Fe+ Fe(OH)2+ + 2H+ →

Ca-EDTA Fe-EDTA

Free Fe + 2H+ + Y → Bound Fe

Shi et al. 2010

Thalassiosira weissflogii

The rate of Fe uptake by phytoplankton

Free Fe + 2H+ + Y → Bound Fe

103

102

101

100

100 101 102 103

Total Fe (nM)

µmol

Fe

mol

C-1

day

-1

pH 7.7

pH 8.1

101

Free Fe (pM)

102 103 104

1:1 pH 8.6

Fe u

ptak

e ra

te

pH effect depends on mature of chelator

Shi et al. 2010

Weak effect of pH on Fe uptake in field

Shi et al. 2010

Complications of OA research

Time scales Adaptation

Ocean warming Temperature

Mixing

CO2

CO32-

pH

PhytoplanktonSuccession

Photochemistry

C-fixation

Transporter

EnzymeExpression

Cell Growth

Competition

Acclimation

Adaptation Genetic mutation

Lab. cultures

Field monitoring

Predictions

Time scales

Log10 Days

geological epoches

nano seconds years

centuries10-14 10-5 0.01 1 100 105 108

Timescales

seconds days

Today Year 2100+ 2 to 6°C

Mixing

Nutrient input

Irradiance

Stratification

Surface temperature

++++/-

Ocean warming: Temperature & Mixing

Temperature

Morel Group

Ja-Myung Kim

Biologically complicated…Chemically simple,