Geoscience Reference
In-Depth Information
two trajectories RCP2.6 and RCP8.5. The size of the anomaly is
clearly dependent on the scenario from 1 to 3°C with RCP2.6 on
France, to 3-5°C with RCP8.5 for the model CNRM-CERFACS. We
note, however, that at high latitudes, the maximum warming is situated
in the Arctic for CNRM-CERFACS whereas model IPSL-CM extends
it over Asia. This regional difference illustrates the critical impact that
the regions covered by ice represent, regions where strong feedbacks
between snow/ice and the climate occur, and where slight variations in
the choice of parameters can lead to divergences.
In terms of precipitation, which is an important parameter for
characterizing a regional climate, it is more difficult to obtain a
consensus from an analysis of the models since the structure of this
field is very heterogeneous spatially and sensitive to slight differences
between models. Nevertheless, some common patterns appear in the
structure of the anomalies. The anomalies in precipitation in the
French models CNRM-CERFACS and IPSL-CM are presented in
Figure 2.6. We can note in general an increase in precipitation in
regions already notable for heavy precipitation (like the intertropical
convergence zone in the Pacific or the north of Europe). However,
decreases in precipitation are making themselves felt in regions that
are already dry, such as the Mediterranean basin. The evolution of
precipitation reflects the intensification of the hydrological cycle,
associated with an increase in the atmosphere's capacity to retain
water; the average residence time of water vapor in the atmosphere
has increased.
As we see in this succinct description of the observations on the
changes underway and the projections from coupled simulation
experiments, the climate system's response is complex and involves
numerous phenomena, on different time scales. We will now
concentrate our attention on the ocean in order to clarify its role in the
climate system.
2.3. Physics and dynamics
Oceans cover 70% of the Earth's surface and hold 97% of its
water. Of the two intricately interlinked fluids, oceans and
