Vulnerability, Impacts and Adaptation of Coastal Zones to Global Change - Vulnerability of Coastal Ecosystems and Adaptation - page 145

the increase in the global mean temperature of the atmosphere at the
surface would have been much larger than the increase observed. The
ocean therefore mitigates, quite considerably, the effect of
anthropogenic greenhouse gas emissions on the temperature of the
Earth's atmosphere.
Another very important aspect is that the oceans and the
cryosphere are the main sources of physical inertia in the climate
system, for timescales in the order of millennia. If we manage to
reduce the anthropogenic greenhouse gas emissions considerably, the
positive radiative forcing on the climate system ceases to increase and
stabilizes. Yet it will take decades, indeed centuries before the mean
temperature of the atmosphere close to the surface reaches an
equilibrium temperature. The ocean's stabilization period is even
longer due to its relatively high thermal capacity, and the slow pace of
vertical thermal exchanges. The heat propagation from the surface to
the oceanic depths occurs very slowly, taking centuries to millennia.
Consequently, the increase in the volume of the ocean due to its
thermal expansion is a very slow process that will last for centuries
and possibly millennia. The response of the cryosphere to the positive
radiative forcing is slower and will probably last even longer.
However, not all the impacts on the cryosphere caused by climate
change lead to an increase in GMSL. The melting of sea ice,
especially in the Arctic, does not contribute to it, except for a slight
increase linked to the difference in density in the water from the
melted sea ice and the sea water. Two types of floating ice can be
distinguished in the polar regions: the vast ice shelves on the coasts of
Antarctica, that form where the glacier reaches the sea, and the sea ice
that covers a large part of the Arctic.
Model-based estimates indicate that, in the period 1993-2010, the
thermal expansion of the upper layers of the ocean contributed an
average 1.1 mm per year to the rise in GMSL, the melting of glaciers,
0.86 mm, the melting of the Greenland ice sheets, 0.33 mm and the
melting of the Antarctica ice sheet, 0.27 mm. When 0.38 mm of
GMSL rise, resulting from the exploitation of aquifers is added to the
equation, a total of 2.94 mm is obtained. This result is in fairly