chapter - Atmospheric and Oceanic Science

Global climatic change
at a global scale, they show notable differences at a regional scale, particularly in
the simulations of the current fields of rainfall and of their future prediction. This
is an important limiting factor at the moment of evaluating the impacts of the climatic
change.
This is in turn also a great limitation to estimate the vulnerability to the climatic
change, since it is to be expected that most of the ecological, economic and
social impacts will be at regional or local scale. However, the models are consistent
in the prediction of some aspects that, though of global character, will emerge in
many regions. For example, an increase of the intensity of the hydrologic cycle is
expected with more intense rainfalls, though in some regions the opposite could
happen. It is estimated that there will be a major frequency and intensity of the
intense precipitations (IPCC 2001b) and in consequence of the phenomena associated
with them, what is already happening in several regions of the planet. In chapter
5 it has been seen that it is already occurring in the La Plata basin.
As a consequence of the oceans thermal expansion and to a lower degree due
to the melting of glaciers and continental mantles of ice, it is estimated that the
mean sea level will increase. As a result, by the 2100 it would be about 60 cm over
its current level. This global effect will be felt with few variants on all the coasts of
the planet, but severe problems can be anticipated in those relatively low as it is the
case of the deltas and estuaries and in the insular states of the Caribbean and
Polynesia, causing huge socioeconomic losses and migrations.
Another global impact that will display uniformly at regional scale is the fertilization
of a great part of the biosphere with the consequent ecological change.
Part of the vegetation has a type of photosynthesis in which the carbon dioxide is a
limiting factor, thus, CO2 increase favours its growth. Other vegetables, on the other
hand, do not change their level of photosynthesis depending on the concentration
of the carbon dioxide. The augment of the concentration of this gas can alter the
ecological balance favouring the expansion of the first type of vegetables at the
expense of the second one. Much more serious will be the effects of the regional
climatic changes on the ecosystems. These can turn out to be very critical in the isolated
systems such as mountains or marshlands where it might come to the massive
extinction of many species and ecosystems. Something similar would happen with
almost all the ecological systems since the human use of the space has led to their
fragmentation and isolation.
Some studies suggest that even in the cases in which the continuity of the
ecosystems is not geographically limited, the speed of the climatic change would
be two or three times greater to the one at which many species could displace.
Because of that, it is growing the idea that if a drastic GHG emission reduction and
their elimination do not take place within the next 50 years, the ecological catastrophe
to come will not have precedents since the mankind appeared in the planet.
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