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Figure 3.5:
Current values and future changes in Arctic bottom-water temperatures. Left: Map of the modern bottom-water temperatures in
an ocean model at 1/2° resolution (1985-2004). Right: Trend in bottom-water warming under elevated pCO
2
as predicted by the Kiel Climate
Model (KCM) (in °C per 100 years). The contour line depicts the 400-metre water-depth contour (From Biastoch
et al.
(2011)).
-2
-1
0
1
2
Mean bottom water temperature (1985-2004), °C
Arctic bottomwater temperature
400 metres isobath
Source: redrawn from Biastoch, A.,
etal
., Rising Arctic Ocean
temperatures cause gas hydrate destabilization and ocean acidi cation
Arctic Ocean
Laptev
Sea
European
Nordic Sea
-2 -1 0
3 4
1 2
5
Mean trend per 100 years, °C
Trend in Arctic bottomwater temperature
400 metres isobath
Source: redrawn from Biastoch, A.,
etal
., Rising Arctic Ocean
Arctic Ocean
Laptev
Sea
European
Nordic Sea
duces a pressure increase at the sea floor and may help to sta-
bilize marine gas hydrates. However, IPCC projections of eu-
static sea-level rise are generally less than two metres by 2100
and not expected to significantly enhance the stability of gas
hydrates, which are more sensitive to temperature than pres-
sure (Ruppel 2000, 2011; Reagan and Moridis 2008). For
example, modelling by Tishchenko
et al.
(2005) shows how
the complete breakdown of the Greenland ice sheet, and the
seven-metre sea level rise it would cause, would only protect
gas hydrates from a ~0.2 °C temperature increase. In fact, as
discussed in Section 3.5.4, sea level rise might actually have
accelerated gas hydrate dissociation along Arctic shelves by
submerging and warming the sediment. Other changes in
the ocean regime, such as sea-ice cover in the Arctic, wave
and current regime, or hydrology, are also not expected to
have a great influence on gas hydrate stability.