In approximately half of the herding districts in Finland, basal ice events occurred more frequently in the period 1983–2016 than in the period 1948–1982. Researchers collected practitioners’ knowledge of herders from the period 1948–2016. During this period, seven winters with extensive basal ice formation were identified. Five out of seven of the most extensive basal ice formation events occurred between 1991 and 2016. Approximately one fourth of all reported mold formation events co-occurred with basal ice formation.
Basal ice formation in the terrestrial snow cover is a common phenomenon
in northern circumpolar areas, one having significant impacts on
ecosystems, vegetation, animals and human activities. Basal ice forming
early in the winter and lasting for prolonged time is a significant
risk for reindeer grazing increasing winter mortality and the need for
the supplementary winter feeding, and decreasing the calving success
during the subsequent spring. Another risk factor associated with warm
and rainy early winters is the growth of mycotoxin-producing molds below
Processes contributing to basal ice formation, such
as thaw or rain and the subsequent freezing of the snow cover, may occur
more often in the future because of warmer winters and more frequent
extreme warm events. There is limited knowledge on the spatial and
temporal occurrence of basal ice formation because of the sparse
observation network and challenges involved in detecting formation
events. Also knowledge on the prevalence and frequency of mold
formation, its relation to weather conditions and potential
co-occurrence with basal ice events is poor. Researchers have now
presented a unique dataset on the annual extent of ice formation events
in northern Finland between 1948 and 2016 based on reindeer herders’
descriptions of the cold season in their management reports.
years are difficult to distinguish using only seasonal means of
meteorological observations or large-scale atmospheric teleconnections
such as the North Atlantic Oscillation. Thorough analysis of local and
short-lived weather events or simulation of snow cover stratigraphy will
be required before detailed explanation of these ice formation events
will be possible.
Results have been reported in an international journal Environmental Research Letters. Research was carried out by Sirpa Rasmus
from the Arctic Centre at the University of Lapland (Finland), Sonja Kivinen
from the University of Eastern Finland and Masoud Irannezhad
form Southern University of Science and Technology (China). The work was funded through NCoE ReiGN by NordForsk.
Arctic Centre, University of Lapland
040 528 2585, email@example.com
University of Eastern Finland
040 588 4185, firstname.lastname@example.org
S., Kivinen, S., Irannezhad, M. 2018. Basal ice formation in snow cover
in Northern Finland between 1948 and 2016. Environ. Res. Lett. 13.
Photo: Ilona Mettiäinen