Climate change in glacial and periglacial regions
641
the open system are abundant; all of them were generated in the Holocene. Also the vast
cryoplanation terraces in the centre of the territory are significant.
It seems that in the Southern Hemisphere the permafrost did not develop so much,
because the described morphologies do not need permafrost conditions. Only ice-wedge
casts in southern Patagonia, Argentina, have been mentioned (Grosso and Corte, 1989).
9. Some considerations on global climate change in periglacial areas
The predicted temperature increase due to the greenhouse effect will seriously affect
permafrost areas, which at present occupies approximately the 25% of the Earth' s surface,
as mentioned above. It is reasonable to state that permafrost will decrease in depth and
extension. An important increase of the active layer will imply substantial modifications
to the hydrologic, geomorphologic and biologic processes of the permafrost regions.
Moreover subsidence problems, affecting the infrastructure will happen. By utilizing
general circulation models (GCMs) and a scientific paleoreconstruction, assuming an
increment in temperature of 2~ it can be concluded that the continuous permafrost
will reduce its extension 29 to 67% during the 21st century in the Northern Hemisphere
(Anisimov and Nelson, 1996). Permafrost areas are the most susceptible to global
warming (Boer and de Groot, 1990; Smith, 1993). Nevertheless, the results obtained from
GCMs do not provide precise forecasts, but indicate the trend of future changes in
permafrost regions (Pissart, 1990).
Several studies indicate that permafrost temperatures have been rising in the last 20
to 30 years. Temperature records taken between 1970 and 1990 in arctic Europe and
subarctic Russia, show an increment of 0.6 to 0.7~ at 3 m depth (Pavlov, 1994). Similar
values have been obtained in Tibet and in North America. The warming is interpreted, as
in other areas of the planet, as the result of the global climate change or due to a natural
trend of climate warming.
641
the open system are abundant; all of them were generated in the Holocene. Also the vast
cryoplanation terraces in the centre of the territory are significant.
It seems that in the Southern Hemisphere the permafrost did not develop so much,
because the described morphologies do not need permafrost conditions. Only ice-wedge
casts in southern Patagonia, Argentina, have been mentioned (Grosso and Corte, 1989).
9. Some considerations on global climate change in periglacial areas
The predicted temperature increase due to the greenhouse effect will seriously affect
permafrost areas, which at present occupies approximately the 25% of the Earth' s surface,
as mentioned above. It is reasonable to state that permafrost will decrease in depth and
extension. An important increase of the active layer will imply substantial modifications
to the hydrologic, geomorphologic and biologic processes of the permafrost regions.
Moreover subsidence problems, affecting the infrastructure will happen. By utilizing
general circulation models (GCMs) and a scientific paleoreconstruction, assuming an
increment in temperature of 2~ it can be concluded that the continuous permafrost
will reduce its extension 29 to 67% during the 21st century in the Northern Hemisphere
(Anisimov and Nelson, 1996). Permafrost areas are the most susceptible to global
warming (Boer and de Groot, 1990; Smith, 1993). Nevertheless, the results obtained from
GCMs do not provide precise forecasts, but indicate the trend of future changes in
permafrost regions (Pissart, 1990).
Several studies indicate that permafrost temperatures have been rising in the last 20
to 30 years. Temperature records taken between 1970 and 1990 in arctic Europe and
subarctic Russia, show an increment of 0.6 to 0.7~ at 3 m depth (Pavlov, 1994). Similar
values have been obtained in Tibet and in North America. The warming is interpreted, as
in other areas of the planet, as the result of the global climate change or due to a natural
trend of climate warming.