Chapter 24
Climate change in glacial and periglacial regions
1. Introduction
Glacial and periglacial regions constitute morphoclimatic zones related to cold. As Tricart
(1967) showed; "cool countries are those in which the geomorphological action of the
water is controlled by its presence as solid state, permanently or periodically." Glaciers are
developed in areas in which the snow does not melt completely from year to year, so that
snow accumulates and in the end it is converted into ice. Limits of the glaciers are clear and
correspond to ice accumulation. Periglacial areas are characterized by frost and thaw, and
snow does not remain from year to year. Frozen soils can develop under the Earth' s surface.
During the last glacial epoch some 30% of the Earth's surface was overlain by ice,
covering vast areas of North America and Eurasia. Also the Antarctic expanded. In
mountainous areas, small icecaps were formed and valley glaciers advanced. Nowadays, ice
occupies 10% of the Earth' s surface. The big advances and recessions of the ice masses have
sculpted wide areas, eroding rock massifs and depositing thick accumulations of glacial
materials. Movements of the glacier fronts respond to climate changes, so they constitute a
source of information for the study of those changes. On the other hand, ice sheets and
glaciers have an important influence on the general system of atmospheric circulation.
As a result of the important advances and recessions of the masses of ice during Quaternary,
the periglacial domain underwent major fluctuations. During glaciations the extent and
location of the periglacial zones were very different from the present. Thus, vast areas that
were covered by ice today were periglacial then. Also, the areas in the surroundings of the ice
that were periglacial, nowadays are temperate zones. Therefore, changes from glacial to
periglacial conditions and from the latter to temperate can be recognized.
On the other hand, there are regions in which the periglacial domain has remained during
the Quaternary. They correspond to areas in which the precipitation is so small that they
cannot generate an icecap, as is the case of wide areas in Siberia (King, 1976a). These
important climatic fluctuations affecting cold areas have generated relict forms, which remain
under new climatic characteristics, and other landforms that correspond to current conditions.
Within both situations there are many inherited and partially eroded landforms that are
difficult to recognize. This aspect adds to doubts on the differentiation of relict and current
landforms.
2. The paleoclimate information provided by drill cores from ice sheets
and deep sea sediments
The studies of ice and sediment samples from boreholes makes possible the knowledge
of past climate changes that have affected the whole planet. Many of these changes have
Climate change in glacial and periglacial regions
1. Introduction
Glacial and periglacial regions constitute morphoclimatic zones related to cold. As Tricart
(1967) showed; "cool countries are those in which the geomorphological action of the
water is controlled by its presence as solid state, permanently or periodically." Glaciers are
developed in areas in which the snow does not melt completely from year to year, so that
snow accumulates and in the end it is converted into ice. Limits of the glaciers are clear and
correspond to ice accumulation. Periglacial areas are characterized by frost and thaw, and
snow does not remain from year to year. Frozen soils can develop under the Earth' s surface.
During the last glacial epoch some 30% of the Earth's surface was overlain by ice,
covering vast areas of North America and Eurasia. Also the Antarctic expanded. In
mountainous areas, small icecaps were formed and valley glaciers advanced. Nowadays, ice
occupies 10% of the Earth' s surface. The big advances and recessions of the ice masses have
sculpted wide areas, eroding rock massifs and depositing thick accumulations of glacial
materials. Movements of the glacier fronts respond to climate changes, so they constitute a
source of information for the study of those changes. On the other hand, ice sheets and
glaciers have an important influence on the general system of atmospheric circulation.
As a result of the important advances and recessions of the masses of ice during Quaternary,
the periglacial domain underwent major fluctuations. During glaciations the extent and
location of the periglacial zones were very different from the present. Thus, vast areas that
were covered by ice today were periglacial then. Also, the areas in the surroundings of the ice
that were periglacial, nowadays are temperate zones. Therefore, changes from glacial to
periglacial conditions and from the latter to temperate can be recognized.
On the other hand, there are regions in which the periglacial domain has remained during
the Quaternary. They correspond to areas in which the precipitation is so small that they
cannot generate an icecap, as is the case of wide areas in Siberia (King, 1976a). These
important climatic fluctuations affecting cold areas have generated relict forms, which remain
under new climatic characteristics, and other landforms that correspond to current conditions.
Within both situations there are many inherited and partially eroded landforms that are
difficult to recognize. This aspect adds to doubts on the differentiation of relict and current
landforms.
2. The paleoclimate information provided by drill cores from ice sheets
and deep sea sediments
The studies of ice and sediment samples from boreholes makes possible the knowledge
of past climate changes that have affected the whole planet. Many of these changes have