A newly published dissertation
by Linda Ampel from the Department of Physical
Geography and Quaternary Geology at Stockholm
University in Sweden examined how rapid climate
changes during the most recent ice age affected
ecosystems in an area in continental Europe.
Rapid and extensive climate
changes have taken place on several occasions
in the past. For example, the latest ice age
(lasting from about 115,000 to 11,500 years
ago) is characterized by several rapid and dramatic
climate swings. These swings recurred in cycles
of roughly 1,500 years and were originally discovered
through studies of ice cores from Greenland
in the early 1990s. These cycles started with
an extremely rapid rise in temperatures, over
just a few years or decades, of as much as 8-16o
C over Greenland.
Linda Ampel studied how these
rapid cycles in the climate affected ecosystems
in an area in continental Europe. The study
was based on analyses of sediment cores from
an overgrown lake named Les Echets in eastern
France and focuses on a time interval between
40,000 and 16,000 ago.
The findings are based on analyses
of fossil silica algae, diatoms. Various species
of diatoms prefer different water conditions
relating to physical and chemical parameters
such as temperature, salinity, access to nutrients,
light, water depth, or available types of places
to grow. These parameters, in turn, are affected
by climate. Different species of diatoms can
therefore indicate how the water environment
changed as a consequence of the climate in the
past.
Diatom analyses of the environmental
archive from Les Echets, together with further
analyses of chemical and biological parameters
such as content of organic material and pollen
grains from trees and other plants preserved
in the lake, show that the ecosystems in the
lake and its surroundings underwent marked changes
during the latest ice age as a consequence of
these 1,500-year cycles. The adaptation of the
ecosystems prompted by the recurring warm periods
took place as quickly as within 50 to 200 years.
"These findings show that
ecosystems have changed rapidly in reaction
to climate changes in the past, which indicates
that quick adaptations could also take place
in the future as a consequence of global warming,
for instance," says Linda Ampel.