Siberia’s thawing permafrost

CASE STUDY: SEASONAL WATER

Siberia’s thawing permafrost

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

Figure 14. Seasonal water changes in Siberia (top) and corresponding temperature trends (bottom) from 2000 to 2019

Sources: UNEP (n.d.); Climate Data Store (n.d.).