Observations of Thermokarst and Its Impact on Boreal Forests in Alaska, U.S.A.

Osterkamp, T. E.; Viereck, Leslie A.; Shur, Yuri; Jorgenson, M. Torre; Racine, Charles H.; Doyle, Allen; Boone, Richard D.

doi:10.1080/15230430.2000.12003368

Cited by 134 publications

(85 citation statements)

References 14 publications

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“…Many studies regard regions of “warm” discontinuous permafrost as being well poised for change [ Osterkamp and Romanovsky , 1999; Hinzman et al , 2005]. Though this may be true, with respect to rate and extent of permafrost thaw and ecosystem impact [ Osterkamp et al , 2000; Jorgenson et al , 2001], results shown here suggest that the continuous‐discontinuous transition may be a more important threshold for groundwater system transformation and its cascade of consequences. This work identifies a need for better characterization of permafrost and other hydrogeologic information in permafrost‐impacted basins (e.g., airborne [ Abraham , 2011; Ball et al , 2011; Minsley et al , 2012] and ground‐based geophysical techniques in YFB [ Nolan et al , 2011]) and integration of such information into site‐specific hydrologic models.…”

Section: Discussionmentioning

confidence: 73%

“…Indeed, it has been found that permafrost is warming and thawing in some areas of Alaska [ Osterkamp and Romanovsky , 1999; Jorgenson et al , 2001; Osterkamp , 2005; Lachenbruch and Marshall , 1986; Jorgenson et al , 2006]. Connections between permafrost degradation and local hydrologic changes have been established [e.g., Osterkamp et al , 2000; Yoshikawa and Hinzman , 2003; O'Donnell et al , 2012]. Yet, the linkage between permafrost degradation and large‐scale changes in hydrologic fluxes is not fully understood, although Michel and van Everdingen [1994], Hinzman et al [2005], and Rowland et al [2010], have provided insightful discussions about such linkages.…”

Section: Introductionmentioning

confidence: 99%

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Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Walvoord

Voss

Wellman

2012

Water Resources Research

256

262

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Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater‐influenced lakes and wetlands, seasonal river‐ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous‐discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground‐based observations.

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Section: Discussionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Walvoord

Voss

Wellman

2012

Water Resources Research

256

262

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“…In regions with active permafrost thaw, soil subsidence promotes C mobilization to water reservoirs through thaw slumps, detachment slides, and gullies (Osterkamp et al. , Jorgenson and Shur , Kokelj and Jorgenson ). The continuous organic matter delivery and subsequent mineralization can sustain consistently high DOC and CO 2 concentration in lakes (Shirokova et al.…”

Section: Discussionmentioning

confidence: 99%

Inland waters and their role in the carbon cycle of Alaska

Stackpoole

Butman

Clow

et al. 2017

Ecological Applications

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Abstract. The magnitude of Alaska (AK) inland waters carbon (C) fluxes is likely to change in the future due to amplified climate warming impacts on the hydrology and biogeochemical processes in high latitude regions. Although current estimates of major aquatic C fluxes represent an essential baseline against which future change can be compared, a comprehensive assessment for AK has not yet been completed. To address this gap, we combined available data sets and applied consistent methodologies to estimate river lateral C export to the coast, river and lake carbon dioxide (CO 2 ) and methane (CH 4 ) emissions, and C burial in lakes for the six major hydrologic regions in the state. Estimated total aquatic C flux for AK was 41 Tg C/yr. Major components of this total flux, in Tg C/yr, were 18 for river lateral export, 17 for river CO 2 emissions, and 8 for lake CO 2 emissions. Lake C burial offset these fluxes by 2 Tg C/yr. River and lake CH 4 emissions were 0.03 and 0.10 Tg C/yr, respectively. The Southeast and South central regions had the highest temperature, precipitation, terrestrial net primary productivity (NPP), and C yields (fluxes normalized to land area) were 77 and 42 g CÁm À2 Áyr À1 , respectively. Lake CO 2 emissions represented over half of the total aquatic flux from the Southwest (37 g CÁm À2 Áyr À1 ). The North Slope, Northwest, and Yukon regions had lesser yields (11, 15, and 17 g CÁm 2 Áyr À1 ), but these estimates may be the most vulnerable to future climate change, because of the heightened sensitivity of arctic and boreal ecosystems to intensified warming. Total aquatic C yield for AK was 27 g CÁm À2 Áyr À1 , which represented 16% of the estimated terrestrial NPP. Freshwater ecosystems represent a significant conduit for C loss, and a more comprehensive view of land-water-atmosphere interactions is necessary to predict future climate change impacts on the Alaskan ecosystem C balance.

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“…When thermokarst develops, subsided areas are more likely to collect water and increase soil moisture content [ Jorgenson et al , 2006], while leaving other nearby areas drier. We observed that soil temperature in subsided areas was higher than in nearby less subsided areas [ Osterkamp et al , 2000; Schuur et al , 2007]. One of the explanations that soil temperatures were higher in thermokarst depressions than in the surroundings is because subsided ground surfaces trap snow during winter as wind redistributes it across the landscape, which then further insulates soil during winter [ Osterkamp , 2007a].…”

Section: Discussionmentioning

confidence: 99%

Soil CO₂ production in upland tundra where permafrost is thawing

2010

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[1] Permafrost soils store nearly half of global soil carbon (C), and therefore permafrost thawing could lead to large amounts of greenhouse gas emissions via decomposition of soil organic matter. When ice-rich permafrost thaws, it creates a localized surface subsidence called thermokarst terrain, which changes the soil microenvironment. We used soil profile CO 2 measurements to understand the response of belowground C emissions for different soil depths from upland tundra as a result of permafrost thaw and thermokarst development. We established sites in central Alaska, where permafrost thaw and thermokarst development had been monitored for the past 2 decades. Cumulative growing season CO 2 production averaged for 3 years (2005)(2006)(2007) ranged from 177 to 270 g CO 2 -C m À2 and was lowest in the least disturbed moist acidic tundra and highest where thawing of permafrost and thermokarst was most pronounced. We were able to explain 55% of variability in growing season soil CO 2 production using surface subsidence, soil temperature, and site differences. This was likely a direct effect of permafrost thaw and thermokarst development and an indirect effect of changes in microsite soil temperature and surface moisture content, which stimulated soil organic matter decomposition and root respiration. We also observed unusually high CO 2 concentrations in the early growing season, which may be attributable to trapped CO 2 within air pockets in the frozen soil. Taken together, these results supported the projection that permafrost thaw and thermokarst development will increase belowground carbon emissions in the upland tundra.Citation: Lee, H., E. A. G. Schuur, and J. G. Vogel (2010), Soil CO 2 production in upland tundra where permafrost is thawing,

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Observations of Thermokarst and Its Impact on Boreal Forests in Alaska, U.S.A.

Cited by 134 publications

References 14 publications

Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Inland waters and their role in the carbon cycle of Alaska

Soil CO₂ production in upland tundra where permafrost is thawing

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Observations of Thermokarst and Its Impact on Boreal Forests in Alaska, U.S.A.

Cited by 134 publications

References 14 publications

Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Influence of permafrost distribution on groundwater flow in the context of climate‐driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Inland waters and their role in the carbon cycle of Alaska

Soil CO2 production in upland tundra where permafrost is thawing

Contact Info

Product

Resources

About

Soil CO₂ production in upland tundra where permafrost is thawing