Simulating the decadal- to millennial-scale dynamics of morphology and sequestered carbon mobilization of two thermokarst lakes in NW Alaska

Thermokarst lakes alter landscape topography and hydrology in widespread permafrost regions and mobilize significant permafrost carbon pools, including releasing methane (CH4) to the atmosphere. Despite this, the dynamics of lake evolution, permafrost thawing, and carbon mobilization are not well kn...

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Bibliographic Details
Published in:Journal of Geophysical Research: Biogeosciences Vol. 117; no. G2
Main Authors: Kessler, M. A., Plug, L. J., Walter Anthony, K. M.
Format: Journal Article
Language:English
Published: Washington Blackwell Publishing Ltd 01.06.2012
Subjects:
Bathymetry
Biogeography
Carbon dioxide
Cryosphere
Freshwater
Geobiology
Hydrology
Lakes
Mathematical models
Methane
modeling
Permafrost
Physics
Pleistocene
Surface water
Thawing
thermokarst
Topography
Water flow
USA, Alaska, Seward Peninsula
USA, Alaska
ISSN:0148-0227, 2169-8953, 2156-2202, 2169-8961
Online Access:Get full text
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Summary:Thermokarst lakes alter landscape topography and hydrology in widespread permafrost regions and mobilize significant permafrost carbon pools, including releasing methane (CH4) to the atmosphere. Despite this, the dynamics of lake evolution, permafrost thawing, and carbon mobilization are not well known. We present a 3‐D numerical model of thermokarst lakes on organic‐rich yedoma permafrost terrains with surface water flow and pooling naturally defining lakes that deepen, expand laterally, and drain due to talik formation, bank retreat, and both gradual and catastrophic drainage. We predict the 3‐D pattern of microbial methane production within the talik over time. As a first model test and calibration, beginning with small protolakes, we simulated 10,000 years of evolution of Pear and Claudi lakes, two neighboring thermokarst features on the northern Seward Peninsula, Alaska. Simulated lakes approximated observed bathymetry, but results are sensitive to initial topography and soil ice content. Local topography caused markedly different dynamics for the two lakes. Pear expanded rapidly across low‐relief topography, fully drained multiple times, and released little methane in later stages due to Pleistocene carbon depletion by the first and largest lake generation. Claudi grew slowly and continuously across high‐relief topography, forming high subaerial banks; partial drainages left remnant horseshoe lakes that continued to expand into virgin yedoma, mobilizing carbon at roughly the same rate irrespective of lake drainage. The ∼2× discrepancy between simulated CH4 production and observed emission rates in Claudi likely results from misestimation of hot spot ebullition, labile carbon content, CH4:CO2 production ratio, or microbial CH4 oxidation. Key Points A 3‐D model simulates thaw lakes and quantifies permafrost carbon mobilization Thermokarst lake expansion is sensitive to topography and landscape history Lake expansion into virgin yedoma dominates CH4 production
Bibliography:ArticleID:2011JG001796
NASA Carbon Cycle Sciences - No. NNX08AJ37G
istex:ED28EBECDD3BDB10934889C9B9DBC9D2786807BF
ark:/67375/WNG-HD49PFP8-1
NSF OPP - No. 0732735
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ISSN:0148-0227
2169-8953
2156-2202
2169-8961
DOI:10.1029/2011JG001796