Monitoring the Responses of Freshwater Ecosystems to Climate Change - Climate Change Impacts on Freshwater Ecosystems - page 87

Table 5.1 Direct and indirect impacts of climate change on lakes. c, t, w: variable relevant in cold (c), temperature (t) or warm (w) ecoregions

Category Response Indicator Justification of indicator c t w

Ice cover Higher air, and thus higher

water temperature, leads to a
shorter ice cover period. The
relationship between air
temperature and timing of
lake ice break-up shows an arc
cosine function. This
nonlinearity results in marked
differences in the response of
ice break-up timing to
changes in air temperature
between colder and warmer
regions.

Ice-cover duration,
timing of ice
break-up, ice
thickness

Ice cover duration is
simple to monitor, e.g. by
remote sensing.

x (x)

Stratification Higher temperatures result in

earlier onset and prolongation
of summer stratification. As a
result, changing mixing
processes occur and systems
may change from dimictic to
warm monomictic. A lack of
full turnover in winter might
lead to a permanent
thermocline in deeper regions.

Duration of
summer
stratification as
reflected by water
temperature

Water temperature
reflects the status of lake
stratification.

x x (x)

Hydrology

Water level Increased temperature and

decreased precipitation in
conjunction with intensive
water use will decrease water
volumes. This will lead to
water level imbalances and, in
many cases, to the complete
loss of water bodies.

Lake surface Easy to monitor by

remote sensing.

(x) (x) x