The catastrophic thermokarst lake drainage events of 2018 in northwestern Alaska: fast-forward into the future
<p>Northwestern Alaska has been highly affected by changing climatic patterns with new temperature and precipitation maxima over the recent years. In particular, the Baldwin and northern Seward peninsulas are characterized by an abundance of thermokarst lakes that are highly dynamic and prone...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-12-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/14/4279/2020/tc-14-4279-2020.pdf |
| Summary: | <p>Northwestern Alaska has been highly affected by changing climatic patterns
with new temperature and precipitation maxima over the recent years. In
particular, the Baldwin and northern Seward peninsulas are characterized by
an abundance of thermokarst lakes that are highly dynamic and prone to lake
drainage like many other regions at the southern margins of continuous
permafrost. We used Sentinel-1 synthetic aperture radar (SAR) and Planet
CubeSat optical remote sensing data to analyze recently observed widespread
lake drainage. We then used synoptic weather data, climate model outputs and
lake ice growth simulations to analyze potential drivers and future pathways
of lake drainage in this region. Following the warmest and wettest winter on
record in 2017/2018, 192 lakes were identified as having completely or
partially drained by early summer 2018, which exceeded the average drainage
rate by a factor of <span class="inline-formula">∼</span> 10 and doubled the rates of the previous
extreme lake drainage years of 2005 and 2006. The combination of abundant
rain- and snowfall and extremely warm mean annual air temperatures (MAATs),
close to 0 <span class="inline-formula"><sup>∘</sup></span>C, may have led to the destabilization of permafrost
around the lake margins. Rapid snow melt and high amounts of excess
meltwater further promoted rapid lateral breaching at lake shores and
consequently sudden drainage of some of the largest lakes of the study
region that have likely persisted for millennia. We hypothesize that permafrost
destabilization and lake drainage will accelerate and become the dominant
drivers of landscape change in this region. Recent MAATs are already within
the range of the predictions by the University of Alaska Fairbanks' Scenarios Network for Alaska and Arctic Planning (UAF SNAP) ensemble climate predictions in
scenario RCP6.0 for 2100. With MAAT in 2019 just below 0 <span class="inline-formula"><sup>∘</sup></span>C at the nearby Kotzebue, Alaska, climate station, permafrost aggradation in drained lake basins will become less likely after drainage, strongly decreasing the potential for freeze-locking carbon sequestered in lake sediments, signifying a prominent regime shift in ice-rich permafrost lowland regions.</p> |
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| ISSN: | 1994-0416 1994-0424 |