Multidecadal climate‐induced changes in Arctic tundra lake geochemistry and geomorphology

Abstract

High-latitude lakes are sensitive indicators of climate and important ecological components of Northern landscapes. The response of Arctic lakes to accelerated 20 th century warming has largely been inferred from paleolimnological and shorter-term observational studies (< 20 yr). Here, we present a long-term observational dataset outlining a suite of chemical, biological, and physical changes in three Russian tundra lakes over a 43-yr period (1953-1996). In all three lakes, epilimnetic water temperature, alkalinity, and calculated pCO 2 , measured during the ice-free period in late summer, increased over time. Over the same period, the rates of primary and bacterial production increased significantly. Permafrost thaw at the base and margins of the lakes likely resulted in the observed increase in size, as measured by average depth, surface area, and total volume. The observed changes show strong correlation with temperature, suggesting an overall pronounced response to warming. Importantly, CO 2 sourced from either in situ or allochthonous respiration of thawed permafrost would indicate the destabilization of a large C reservoir.

Phylogenetic diversity and environment form assembly rules for Arctic diatom genera—A study on recent and ancient sedimentary DNA

“…Until recently, it is still unclear whether diatoms can generally adapt to recent global climate change (Irwin, Finkel, Müller‐Karger, & Troccoli Ghinaglia, ) and if vegetation changes, which already resulted in the greening and browning of the tundra (Fu, Su, Wang, & Sui, ; Lara, Nitze, Grosse, Martin, & McGuire, ), will eventually cause the disappearance of specific diatoms along with the potential loss of the tundra biome in the future. Furthermore, temperature‐related variables, like ice cover duration, thermal stratification (Rühland, Priesnitz, & Smol, ), primary production (Drake et al, ) and nutrient availability in Arctic lakes (Pestryakova et al, ) are affected by recent global warming. Lacking thermal stratification and nutrient increase (Sienkiewicz, Gąsiorowski, & Migała, ) as well as the lengthening of the growing season (Smol et al, ) resulted in drastic replacements of established diatom assemblages.…”

Carbon emission from thermokarst lakes in NE European tundra

“…CO 2 and CH 4 emissions have been assessed for a single lake and river in the Vorkuta region (Heikkinen et al 2004); however, seasonal variations of CO 2 emissions have been measured in three thermokarst lakes of this same region (Marushchak et al 2013). There is recent interest in the BZT as over past decades lakes in this territory exhibited sizeable increases in summer temperature and pCO 2 , presumably due to enhanced bacterial respiration of allochthonous dissolved organic matter (DOM) from thawing permafrost (Drake et al 2019).…”

Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

“…The dominant vegetation in the tundra zone is mosses, lichens and dwarf shrubs. Over past decades, the lakes of the BZT have exhibited a sizable increase in summer time temperature and pCO 2 , presumably due to the enhanced bacterial respiration of allochthonous DOM from thawing permafrost (Drake et al, 2019). We sampled surface waters along the typical hydrological continuum (shown in Fig.…”