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Box 3.2 Methane release along the East Siberian Arctic Shelf

In the East Siberian Arctic Shelf (ESAS, Fig. TB-3.2.1), methane concentrations in the surface waters exceed typical seawater values and far exceed the atmosphere’s equilibrium methane concentrations (Shakhova et al. 2010a). Shakhova et al. (2010b) suggest methane is released into the atmosphere at an annual rate of about 8 Tg of carbon (.008 GtC) for the ESAS alone, East Siberian Arctic Shelf

comparable to the rate expected for the rest of Earth’s oceans combined. The present-day ESAS methane release rate is nearly 2 per cent of the nearly 450 Tg of methane carbon (.45 GtC) annually released to the atmosphere from all sources globally (IPCC, 2007). A current research challenge is to predict whether methane release rates will increase significantly in response to ongoing climate change.

East Siberian Arctic Shelf

NORTH POLE

R

s

.

M

o

e

n

d

e

l

e

e

v

R

i

d

g

e

v

Y

e

G

r

Chukchi Sea

m

a

R

a

k

i

k

d

k

g

P

e

e

.

l

R

i

d

g

e

EAST SIBERIAN ARCTIC SHELF

Arctic Ocean

East Siberian Sea

Depth, metres

Barents Sea

0

Kara Sea

100

1000 2000 3000 5000

Source: adapted from NOAA

Figure TB-3.2.1: East Siberian Arctic Shelf (ESAS). The ESAS makes up a quarter of the Arctic shelf area (Shakhova et al. 2010a), with an average depth of only 58 metres (Jakobsson 2002) and significant riverine input.

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