Evidence for warming and thawing of discontinuous permafrost in Alaska

Osterkamp, T. E.; Romanovsky, V. E.

doi:10.1002/(sici)1099-1530(199901/03)10:1<17::aid-ppp303>3.0.co;2-4

Cited by 517 publications

(411 citation statements)

References 25 publications

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“…Ice extent in September (the month of the seasonal minimum) has decreased by at least twice this rate (Parkinson et al, 1999;Comiso, 2000Comiso, , 2001Cavalieri et al, 2003;Stroeve et al, 2005) and the past four Septembers (2002Septembers ( through 2005 have seen extreme minima (Serreze et al, 2003;Stroeve et al, 2005; http://www.nsidc.org/data/seaice index/). There are also indications of decreased sea ice thickness and volume (Rothrock et al, 2003;Rothrock and Zhang, 2004;Lindsay and Zhang, 2005), warming of soils and permafrost (Osterkamp and Romanovsky, 1999), increased precipitation (Groves and Francis, 2002), and rising discharge from Arctic-draining rivers in Siberia (Peterson et al, 2002). Northern Hemisphere snow cover has exhibited modest negative anomalies since the late 1980s, largely owing to spring and summer deficits, but with large interannual and spatial variability (e.g., Robinson and Frei, 2000;Armstrong and Brodzick, 2001).…”

Section: Introductionmentioning

confidence: 99%

The Arctic Amplification Debate

2006

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Abstract. Rises in surface air temperature (SAT) in response to increasing concentrations of greenhouse gases (GHGs) are expected to be amplified in northern high latitudes, with warming most pronounced over the Arctic Ocean owing to the loss of sea ice. Observations document recent warming, but an enhanced Arctic Ocean signal is not readily evident. This disparity, combined with varying model projections of SAT change, and large variability in observed SAT over the 20th century, may lead one to question the concept of Arctic amplification. Disparity is greatly reduced, however, if one compares observed trajectories to near-future simulations (2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023)(2024)(2025)(2026)(2027)(2028)(2029), rather than to the doubled-CO 2 or late 21st century conditions that are typically cited. These near-future simulations document a preconditioning phase of Arctic amplification, characterized by the initial retreat and thinning of sea ice, with imprints of low-frequency variability. Observations show these same basic features, but with SATs over the Arctic Ocean still largely constrained by the insulating effects of the ice cover and thermal inertia of the upper ocean. Given the general consistency with model projections, we are likely near the threshold when absorption of solar radiation during summer limits ice growth the following autumn and winter, initiating a feedback leading to a substantial increase in Arctic Ocean SATs.

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Section: Introductionmentioning

confidence: 99%

The Arctic Amplification Debate

2006

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“…However, more recently, other indirect impacts of climate warming on hydrological processes have been considered. For instance, permafrost thaw due to climate warming [6,7] alters how water is routed and stored in watersheds, and thus impacts both surface and subsurface hydrology [8,9]. Also, a temperature-induced shift of precipitation from snow towards rain and seasonal shifts of precipitation can influence hydrologic processes and regimes [10,11].…”

Section: Introductionmentioning

confidence: 99%

Increasing Winter Baseflow in Response to Permafrost Thaw and Precipitation Regime Shifts in Northeastern China

Duan

Man

Kurylyk

et al. 2017

Water

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Abstract:Rapid permafrost thaw and precipitation regime shifts are altering surface and subsurface hydrological processes in arctic and subarctic watersheds. Long-term data (40 years) from two large permafrost watersheds in northeastern China, the Tahe River and Duobukuer River watersheds, indicate that winter baseflows are characterized by significant positive trends of 1.7% and 2.5%·year −1 , respectively. Winter baseflows exhibited statistically significant positive correlations with mean annual air temperature and the thawing index, an indicator of permafrost degradation, for both watersheds, as well as the increasing annual rainfall fraction of precipitation for the Duobukuer River watershed. Winter baseflows were characterized by a breakpoint in 1989, which lagged behind the mean annual air temperature breakpoint by only two years. The statistical analyses suggest that the increases in winter baseflow are likely related to enhanced groundwater storage and winter groundwater discharge caused by permafrost thaw and are potentially also due to an increase in the wet season rainfall. These hydrological trends are first apparent in marginal areas of permafrost distribution and are expected to shift northward towards formerly continuous permafrost regions in the context of future climate warming.

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“…One of the most important factors, though, is likely to be snow. Changes in the magnitude and timing of snowfall, snow depth, and snow-season length can all modulate the soil's response to surface warming (Osterkamp and Romanovsky 1999). Snow is a strong insulator of the ground and substantially influences the ground thermal regime (Goodrich 1982;Stieglitz et al 2001;Zhang 2005).…”

Section: Introductionmentioning

confidence: 99%

The contribution of snow condition trends to future ground climate

2009

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Global climate models predict that terrestrial northern high-latitude snow conditions will change substantially over the twenty-first century. Results from a Community Climate System Model simulation of twentieth and twenty-first (SRES A1B scenario) century climate show increased winter snowfall (?10-40%), altered maximum snow depth (-5 ± 6 cm), and a shortened snow-season (-14 ± 7 days in spring, ?20 ± 9 days in autumn). By conducting a series of prescribed snow experiments with the Community Land Model, we isolate how trends in snowfall, snow depth, and snow-season length affect soil temperature trends. Increasing snowfall, by countering the snowpackshallowing influence of warmer winters and shorter snow seasons, is effectively a soil warming agent, accounting for 10-30% of total soil warming at 1 m depth and *16% of the simulated twenty-first century decline in near-surface permafrost extent. A shortening snow season enhances soil warming due to increased solar absorption whereas a shallowing snowpack mitigates soil warming due to weaker winter insulation from cold atmospheric air. Snowpack deepening has comparatively less impact due to saturation of snow insulative capacity at deeper snow depths. Snow depth and snow-season length trends tend to be positively related, but their effects on soil temperature are opposing. Consequently, on the century timescale the net change in snow state can either amplify or mitigate soil warming.Snow state changes explain less than 25% of total soil temperature change by 2100. However, for the latter half of twentieth century, snow state variations account for as much as 50-100% of total soil temperature variations.

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Evidence for warming and thawing of discontinuous permafrost in Alaska

Cited by 517 publications

References 25 publications

The Arctic Amplification Debate

The Arctic Amplification Debate

Increasing Winter Baseflow in Response to Permafrost Thaw and Precipitation Regime Shifts in Northeastern China

The contribution of snow condition trends to future ground climate

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