1

CO2 , OCEANS, AND CLIMATE

V.M.CANUTO

NASA, GODDARD INSTITUTE FOR SPACE STUDIESAND

DEPT. APPLIED PHYS. AND MATH., COLUMBIA UNIV., NY, NY

CONVEGNO:CLIMA, ENERGIA, SOCIETA’

ROMA, OCTOBER 13-14, 2009

2

Everything should be made

as simple as possible

but not simpler

A. Einstein

3

4

6

A MIDGET AMONG GIANTS

THE BREATHING PLANET

5

SINCE THE BEGINNING OF THE INDUSTRIAL REVOLUTION

ANTHROPOCENE

HUMANKIND HAS EMITTED LARGE AMOUNTS OF CO2INTO THE ATMOSPHERE

1800-1994 1980-1999 1980-1999

GtC 244±20 117±5 GtC/yr: 5.9 ± 0.3Ocean uptake -118±19 -37±7 1.9±0.4 (30%)

Atmospheric absorption -165±4 -65±1 3.3±0.1 (60%)

REAL WORLD:1800: 280 ppm

NO OCEANS:

TODAY: 380 ppm

TODAY: 380+55 = 435 ppm

6

7

Not evenly distributed

North Atlantic, 15% area, 23% total, Highest vertically

integrated concentration

Southern Ocean : only 9% global inventory (GI)

More than 40% of the GI 50S-14S

Southern Hemisphere: 60% of the GI

!

!

!

!

!

8

CO2 DEPTH DISTRIBUTION

30% depths shallower than 200m

50% depths above 400m

MIXED LAYER VS. THERMOCLINE

Mixed Layer : T constant 200m

Thermocline: T varies rapidly with depth

!!

!!

9

IT IS A QUESTION OF STRATIFICATION...

OCEAN : HEATED FROM ABOVE

WARM WATERS FLOAT (BUOYANT)

COLD WATERS SINK

STABLY STRATIFIED

NORTH ATLANTIC (400m)

NORTH PACIFIC (200m) (NUTRIENT DEFICIENT!)

TO MIX IT, YOU NEED ENERGY (SALAD

DRESSING SYNDROME!)

!!!!!!!

10

Tidal flow hits topography

=> internal waves=> dissipation of the energy

carried by those waves => mixing

[Garrett, Nature 2003]

11

ENERGY SOURCES

WINDS: 1 TW

TIDES : 3.5 TW

!

! "

"

12

13

21E= I!2

dE = Idt

##!

astronomical data#$!

" 3TW"

TIDES

P.S.: “We are losing the Moon”

14

TIDES

A few decades ago the suggestion that the Moon played a role in determining global ocean properties was considered lunatic; now it is considered obvious (Wunsch and Munk were more comfortable working in the earlier times).

(Munk and Bills, 2007, JPO)

21E I!t 2%

& '%

3.5TW!

15

16

STRATIFICATION TVERY WELL MIXEDMORE NUTRIENTS RISE FROM THE BOTTOMMORE PHYTOPLANKTONMORE CO2 ABSORBED

STRATIFICATION T

PHYTOPLANKTON SPENDS MORE TIME EUPHOTIC ZONE, BUTNUTRIENTS MAY BE LESS AVAILABLE…

WHICH ONE IS IT? UP OR DOWN?TODAY:ALL OCEAN MODELS HAVE A VERY, VERY LOW STRATIFICATION IN THE FIRST 200 METERS

!

!!

!!!

!

17

WHY?

THEY ONLY INCLUDE:

1D : VERTICAL TURBULENT MIXING, SCALE METERS,FICKIAN DIFFUSION

THEY LACK:

2D: TURBULENCE

MESOSCALES

HORIZONTAL SCALES (10-100)km

LIFE TIMES MONTHS

!

!

!

!

""

18

fig 1:Area for data extraction

fig 2: Maps of Sea Level Anomaly, Kuroshio area, cm

fig 3: Maps of geostrophic velocity anomalies, Kuroshio area, cm/s

fig 4: Maps of Absolute Dynamic Topography, Kuroshio area, cm

19

MESOSCALES

BAROCLINIC INSTABILITIES: NOT FICKIAN DIFFUSION

MIX: DO NOT DIFFUSE BUT STIR

THE PIZZA CONNECTION: KNEADING THE DOUGH

THE DRY MARTINI CONNECTION!

!

!

!

20

21

HORIZONTAL GRADIENTS VERTICAL FLUXES!

M DH V V

T T F Fz z z

% % %( )* ( ( &

% % %u #

*M

V HF Tz%

& )*%

u

!

! MISSING

BAROCLINIC INSTABILITIES

22

-6 -4 -2 0 2 4 6

-200

-160

-120

-80

-40

0

Z (m

)

Fv and -kvN2 (108m2s-3)

mesoscalediffusive

-2 0 2 4 6

-200

-160

-120

-80

-40

0

Z (m

)

-0.6 -0.4 -0.2 0 0.2 0.4

-200

-160

-120

-80

-40

0

Z (m

)

-%+zzFv and %+zzkvN2 (1010s-3)

mesoscalediffusive

(Fv-kvN2) (108m2s-3)

-0.4 -0.3 -0.2 -0.1 0 0.1

-200

-160

-120

-80

-40

0

Z (m

)

buoyancy loss

-%+zzFv + %+zzkvN2 (1010s-3)

D: Diffusion, M: Mesoscales

Mesoscale vertical flux versus vertical diffusion

D D M D+MM

23

HOW DO YOU ASSESS A

MESOSCALE MODEL?

OGCMs? NO

OFF-LINE? YES

!!

24

DATA

MODEL

25

RESULTS

LESS MIXING

LESS CO2 ABSORBED BY THE OCEANS

MORE CO2 ATMOSPHERE

INCREASED GHG

HIGHER TEMPERATURE !

26

J.Climate 2006:

“Unanimous agreement that future climate change will reduce the efficiency to absorb CO2.”

Tellus, 2005:

“ 50% decrease of surface mixing causes 25 ppm increase in atmospheric CO2 in 2100.”

27

OCEANS

HUGE HEAT CAPACITY

FIRST 2.5m UPPER OCEAN EQUIVALENT

TO THE ENTIRE TROPOSPHERE!

!

28

THE SMOKING GUNS …

OCEANS ARE WARMING UP

1950 2000

29

Global Sea Level Rise, 1870-2006

UNEP, 2007

30

Greenland Mass Loss – From Gravity Satellite

31

SYNOPSIS

4X109 yrs ago: life on earth began in the oceans

500X106 yrs ago: life emerged from the oceans

0.004%: humankind on earth

working against the oceans’ buffering action

as a CO2 sink

future: will the oceans suffocate us?

!!

!

!

!

32

33

34

35

Cao, L., and K. Caldeira,

2008, GRL, 35

36

37

38

KEELING CURVE

39

40

Surface Temperature Reconstructions

Mann, M.E., The Value of Multiple Proxies Science, 297, 1481-1482, 2002.

41

Rates of sea level rise, late 20th century

Contributions to SLR

SLR 1961-2003, mm/yr SLR 1993-2003, mm/yr

Thermal expansion 0.42±0.12 1.6±0.5

Glaciers and ice caps 0.50±0.18 0.77±0.22

Greenland ice sheet 0.05±0.12 0.21±0.07

Antarctic ice sheet 0.14±0.41 0.21±0.35

Total 1.1±0.5 2.8±0.7

Observed 1.8±0.5 3.1±0.7

Difference (Obs.-

total) 0.7±0.7 0.3±1.0

IPCC, 2007

42

Contributors to SLR

B1 B2 A1B A1T A2 A1F1

Thermal expansion

0.10 to 0.24 0.12 to 0.28 0.13 to 0.32 0.12 to 0.30 0.14 to 0.35 0.17 to 0.41

Mountain glaciers

0.07 to 0.14 0.07 to 0.15 0.08 to 0.15 0.08 to 0.15 0.08 to 0.16 0.08 to 0.17

Greenland 0.01 to 0.05 0.01 to 0.06 0.01 to 0.08 0.01 to 0.07 0.01 to 0.08 0.02 to 0.12

Antarctica -0.10 to -0.02 -0.11 to -0.02 -0.12 to -0.02 -0.12 to -0.02 -0.12 to -0.03 -0.14 to -0.03

Land ice sum 0.04 to 0.18 0.04 to 0.19 0.04 to 0.20 0.04 to 0.20 0.04 to 0.20 0.04 to 0.23

Total SLR 0.18 to 0.38 0.20 to 0.43 0.21 to 0.48 0.20 to 0.45 0.23 to 0.51 0.26 to 0.59

Sea level rise (m), 1980-1999 to 2090-2099 Numbers represent the 5-95% range

IPCC, 2007

43

Attribution• are observed

changes consistent with

!expected responses to forcings

!inconsistent with alternative explanations

Observations

All forcing

Solar+volcanic

44Fig. 2 of Barnett et al., 2005, Science, 309

45Fig. 3 of Barnett et al., 2005, Science, 309

46

Projected Sea Level Rise, 21st Century

UNEP, 2007

47

48

Drag Internal tides

Total

Shallow Seas 1.49 0.98 2.47Deep Ocean 0.01 1 1.02Total 1.51 1.98 3.5

T/P

49

Internal tides are internal gravity waves generated in stratified waters by the interaction of barotropic tidal currents with variable bottom topography. They play a role in dissipating tidal energy and lead to mixing in the deep ocean.

Garrett and Kunze, 2007

u O(1) mm/sec"

tidesu O(10) mm/sec"

50

Annual cycle of simulated and observed (dotted lines, Reynolds and Smith 1994) mixed layer depth for three selected sites: the Bermuda Atlantic Times Series Study (BATS: 32N, 65W), the North Atlantic Bloom Experiment (NABE: 47N, 20W), and the Ocean Weather Station India (OWS I: 59N, 19W).

Solid line: 1/9 degree, dashed line: 1/3 degree.

A. Oschlies, JPO, 2002, 32, 2277