Geoscience Reference
In-Depth Information
at the projected rise in sea level, extreme storm surges, and waves from the standpoint of
protecting life, property, and infrastructure in coastal regions.
High-latitude regions are particularly vulnerable to change. The Arctic is undergoing
changewhichhasthepotentialforsignificantconsequencesinrelationtotheglobalclimate
system, marine ecosystems, and human activities such as oil and gas exploration/exploit-
ation and shipping. The salinity-driven stratification in the upper layers of high-latitude
oceans is being altered as a consequence ofan accelerated hydrological cycle and increased
ice melting during the summer season. This has consequences for the food web and also in
relation to invasion by species new to these areas. In the Arctic, documented change (de-
creases in the extent, thickness, and duration of the ice cover and the measured increase in
ocean temperature in some parts of the Arctic Basin) is occurring relatively fast in com-
parison with other regions. Because of the interdependence between ocean basins, these
changes have possible consequences at the global scale. A growing concern is that related
to the Antarctic and Southern Ocean system, which is adapted to very stable conditions. In
this area, however, observed and projected sea surface temperatures are too low to indicate
whether significant ice melting is occurring, which calls for continued scientific observa-
tions of the Antarctic and Southern Ocean domain.
Future changes in ocean circulation and stratification are highly uncertain. The overall
reaction of marine biological carbon cycling to a warm and high CO
2
world is not well
understood, which is a cause for concern in the light of the ongoing debate about geo-en-
gineering the planet.
Global change also has various consequences on ocean life, marine biodiversity, eco-
system functioning, and the services which ecosystems provide. These changes also con-
cern deep-sea ecosystems which, contrary to the notion that they are extremely stable in
terms of physico-chemical conditions, are also experiencing changes such as climate-driv-
en temperature shifts, as a direct consequence of the prevailing surface climate conditions.
Climate-induced changes may differ strongly throughout the globe, especially along
a latitudinal gradient (in general, warming appears more pronounced at the poles than at
the equator). Changes in the global mean surface air temperature, not only over the past
