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Tundra vegetation productivity and composition are responding rapidly to climatic changes in the Arctic. These changes can, in turn, mitigate or amplify permafrost thaw. In this Review, we synthesize remotely sensed and field-observed vegetation change across the tundra biome, and outline how these shifts could influence permafrost thaw. Permafrost ice content appears to be an important control on local vegetation changes; woody vegetation generally increases in ice-poor uplands, whereas replacement of woody vegetation by (aquatic) graminoids following abrupt permafrost thaw is more frequent in ice-rich Arctic lowlands. These locally observed vegetation changes contribute to regional satellite-observed greening trends, although the interpretation of greening and browning is complicated. Increases in vegetation cover and height generally mitigate permafrost thaw in summer, yet, increase annual soil temperatures through snow-related winter soil warming effects. Strong vegetation–soil feedbacks currently alleviate the consequences of thaw-related disturbances. However, if the increasing scale and frequency of disturbances in a warming Arctic exceeds the capacity for vegetation and permafrost recovery, changes to Arctic ecosystems could be irreversible. To better disentangle vegetation– soil– permafrost interactions, ecological field studies remain crucial, but require better integration with geophysical assessments.
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Rapid Saline Permafrost Thaw Below a Shallow Thermokarst Lake in Arctic Alaska
Permafrost warming and degradation is well documented across the Arctic. However, observation‐ and model‐based studies typically consider thaw to occur at 0°C, neglecting the widespread occurrence of saline permafrost in coastal plain regions. In this study, we document rapid saline permafrost thaw below a shallow arctic lake. Over the 15‐year period, the lakebed subsided by 0.6 m as ice‐rich, saline permafrost thawed. Repeat transient electromagnetic measurements show that near‐surface bulk sediment electrical conductivity increased by 198% between 2016 and 2022. Analysis of wintertime Synthetic Aperture Radar satellite imagery indicates a transition from a bedfast to a floating ice lake with brackish water due to saline permafrost thaw. The regime shift likely contributed to the 65% increase in thermokarst lake lateral expansion rates. Our results indicate that thawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic faster than anticipated.
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- PAR ID:
- 10475439
- Publisher / Repository:
- Geophysical Research Letters
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 50
- Issue:
- 22
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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This dataset supports the findings of the research paper submitted to the journal Geophysical Research Letters that documents the rapid thaw of saline permafrost below a shallow thermokarst lake near Utqiagvik, Alaska. The lake, East Twin Lake, is located in the Barrow Environmental Observatory. We conducted repeat drilling-based surveys at East Twin Lake in the Barrow Environmental Observatory near Utqiagvik, Alaska between 2008 and 2023. These field data were integrated with transient electromagnetic (TEM) near-surface geophysics soundings in 2016 and 2022 and analysis of a time-series of wintertime Synthetic Aperture Radar (SAR) satellite imagery from 2015 to 2023 to assess changes in lake and sub-lake properties. Finally, we assessed the impact of thawing saline permafrost on shore erosion by quantifying a regime shift in the lateral expansion rate of East Twin Lake between 1948 and 2022. The datasets consist of a CSV file with the point measurements from the drilling campaign, processed TEM data along with the script, a table of SAR backscatter values extracted for three lakes, and a table with lake expansion rates for East Twin Lake.more » « less
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1029/2023GL105552
