Surprisingly high anthropogenic CO2 in the eastern Mediterranean

A. Schneider, T. Tanhua, A. Körtzinger, D.W.R. Wallace

Thermohaline circulation

Meteor 51/2 in 2001

• Salinity, Temperature, Oxygen• Dissolved inorganic carbon• Total alkalinity• CFC-12

Thyrranian Sea

Transit time distribution (TTD)

Mean age

CFC-12 concentrations

TTD with a mean age

Atmospheric history of CO2 + TTD

Anthropogenic carbon (Cant)

Results

Total Cant Inventories

Mediterranean Sea compared to World Ocean:

0.3 % of the water volume

1.1 % of the Cant

Hypothesis

Why is the uptake higher?

• Low Revelle Factor (9-10)

• Deep water formation

Conclusions

• CFC-12 and Cant have penetrated the entire water column

• High Cant inventories

• Deep water formation areas are of great importance

• Influence on the global ocean

• Measurements in the marginal seas are needed

Flux calculations

Water Volume [Sv]

Cant

[Tg C yr-1]

Atlantic inflow +0.89 +21.6

Mediterranean outflow -0.85 -18.0

Net flux +0.04 +3.6

• Good agreement with Huertas et al. 2009 using the ΔC* method: +4.2 Tg C yr-1

• Aït-Ameur & Goyet using the TrOCA method: opposite flux

Cant Column Inventories

from Waugh et al. 2006

Transit time distribution (TTD)

Age1Age3

Age2

Age2

Age3Age1

Transit time distribution (TTD)

CFC-12 concentrations

atmospheric history

assumptions for saturation and mixing

Transit time distribution (TTD)

Mean age

Transit time distribution (TTD)A

nthropogenic CO

2 [ppm]

100

80

70

60

50

90

120

110

You get:

Anthropogenic Carbon (Cant)

Transit time distribution (TTD)

Transit time distribution (TTD)

Mean age = 30 yrs

Width = 0.1

Width = 1

Width = 10

Width = 30

Width = 45

Width = 15Mean age = 30

Width = 30Mean age = 30