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Arctic bottomwater temperature

Trend in Arctic bottomwater temperature

Laptev Sea

Laptev Sea

Arctic Ocean

Arctic Ocean

European Nordic Sea

European Nordic Sea

Mean bottom water temperature (1985-2004), °C

Mean trend per 100 years, °C

-2

-1

0

1

2

-2 -1 0

1 2

3 4

5

400 metres isobath

400 metres isobath

Source: redrawn from Biastoch, A., etal ., Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidi…cation

Source: redrawn from Biastoch, A., etal ., Rising Arctic Ocean

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)).

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.

FROZEN HEAT 58