Even the general loss of ice cover through shrink-
age of the ice season has been identified as a major
economic concern for some northern regions where
winter river-ice and lake-ice road networks currently
provide essential and relatively inexpensive access to
communities and industrial developments
35,36
. Loss
of ice-based transportation (Figure 8.6) and ice-relat-
ed effects on aquatic systems that influence fish and
small mammal productivity will be especially impor-
tant for small indigenous communities, particularly
in the Arctic
7,36
. Many indigenous people depend
on frozen lakes and rivers for access to traditional
hunting, fishing (Figure 8.7), reindeer herding or
trapping areas, and for some isolated communities
winter travel on frozen rivers is the principle access
to larger centres.
Impacts on biological productivity
Freshwater-ice covers control most major interac-
tions between the atmosphere and the underlying
aquatic systems (for example solar radiation, thermal
regimes and oxygen levels), and hence biological pro-
ductivity. Reductions in lake-ice covers under future
climates will produce changes in temperature and
light levels, water circulation patterns and aquatic
UV radiation exposure, all of which are important to
biological productivity and diversity
37,38
. Of particu-
lar concern are variations and change in light and
nutrient availability, water circulation patterns, and
layering of warm and cold water during the ice-off
period. In general, the life cycles of most aquatic or-
ganisms are linked with ice cover and temperature,
and future changes in these will result in unpredict-
able responses (see box on alpine lakes).
Figure 8.7: Lake ice fishing, Nunavut, Canada.
Photo: Shari Gearheard
208 GLOBAL OUTLOOK FOR ICE AND SNOW