CASE STUDY: SEASONAL WATER
Siberia’s thawing permafrost
Changes in thermokarst lakes have been associated with changes in temperatures,
Above-average rates of warming in the Arctic
precipitation and snow cover, with climatic
(Anisimov and others, 2007) have led to changes
effects, surface geology and very flat terrain
in the lake-rich ecosystems of the continuous
(which is impacted by seawater flooding) also
permafrost zone. Many of the lakes in
responsible (Nitze and others, 2017). These
permafrost regions are likely of thermokarst
changes affect around 2 million people – mainly
origin (Grosse, Jones and Arp, 2013), meaning
indigenous – living in north-central and north-
they are formed in a depression left by thawing
eastern Siberia, whose livelihoods depend
permafrost (Bryksina and Polishschuk, 2015).
heavily on fishing, hunting and reindeer
Patterns of general lake expansion are a
husbandry, all of which are impacted by climate
common feature of continuous permafrost
conditions. More frequent thawing, earlier
zones (Smith and others, 2005). In western
melting and later river-ice formation are affecting
Siberia, thermokarst lakes have been increasing
animals’ migration patterns, which is testing the
at a faster rate in the continuous permafrost
resilience of these communities. More frequent
zone than in the discontinuous permafrost zone
and severe seasonal floods are also destroying
(Chetan and others, 2020; Vonk and others,
vital infrastructure and threatening entire villages
2015). Typically, thermokarst lakes are shallow,
with permanent flooding (Stambler, 2020).
though their depths vary significantly depending
Climate change is accelerating permafrost
on the season, with some parts even drying out
thawing, which in turn is generating further
in summer (Manasypov and others, 2020), as
climate change. Furthermore, Arctic thermokarst
their main source of water comes from
lakes are both methane point sources and
atmospheric precipitation and spring snowmelt.
potential carbon dioxide sinks, which means
Western Siberian lakes tend to be shallower than
their expansion can lead to large-scale increases
Alaskan and Canadian thermokarst lakes of
or decreases in greenhouse gas emissions, thus
similar size.
indicating an urgent need for them to be better constrained (in ‘t Zandt, Liebner and Welte, 2020).
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PROGRESS ON FRESHWATER ECOSYSTEMS - 2021
