Overlooked volatile production from Arctic permafrost triggered by global warming

Permafrost thaw, as a consequence of climate warming, liberates large quantities of frozen organic carbon in the Arctic regions. The response of gaseous carbon release upon permafrost thaw might play a crucial role in the future evolution of atmosphere-land fluxes of biogenic gases such as volatile organic compounds (VOCs), a group of reactive gases and the dominant modulator of tropospheric oxidation capacities. Here, we examine the response of volatile release from Finnish Lapland permafrost soils to temperature increase in a series of laboratory incubation experiments. The experiments show that when the temperature rises from 0 &#176;C to 15 &#176;C, various VOC species are significantly emitted from the gradually thawing soils. The VOC fluxes from thawing permafrost are on average four times as high as those from active layer. Acetic acid and acetone dominate the total volatile emissions from both permafrost and active layer, with significant amounts of aromatics and terpenes detected as well. The emission rate and the composition of volatile release from thawing soils are highly responsive to temperature variations. As temperature increases, more less volatile compounds are released, i.e., sesquiterpenes and diterpenes. Collectively, these results demonstrate the highly overlooked volatile production from thawing permafrost, which will create a stronger permafrost carbon-climate feedback.

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Microbial network, phylogenetic diversity and community membership in the active layer across a permafrost thaw gradient

10.1101/143578 ◽

2017 ◽

Cited By ~ 1

Author(s):

Rhiannon Mondav ◽

Carmody K McCalley ◽

Suzanne B Hodgkins ◽

Steve Frolking ◽

Scott R Saleska ◽

...

Keyword(s):

Active Layer ◽

Radiative Forcing ◽

Phylogenetic Diversity ◽

Microbial Interactions ◽

Climate Feedback ◽

Microbial Composition ◽

Permafrost Thaw ◽

Microbial Network ◽

Alpha Beta ◽

Thawing Permafrost

SummaryBiogenic production and release of methane (CH4) from thawing permafrost has the potential to be a strong source of radiative forcing. We investigated changes in the active layer microbial community of three sites representative of distinct permafrost thaw stages at a palsa mire in northern Sweden. The palsa sites with intact permafrost, and low radiative forcing signature had a phylogenetically clustered community dominated byAcidobacteriaandProteobacteria.The bog with thawing permafrost and low radiative forcing signature was dominated by hydrogenotrophic methanogens andAcidobacteria, had lower alpha diversity, and midrange phylogenetic clustering, characteristic of ecosystem disturbance affecting habitat filtering, shifting from palsa-like to fen-like at the waterline. The fen had no underlying permafrost, and the highest alpha, beta and phylogenetic diversity, was dominated byProteobacteriaandEuryarchaeota,and was significantly enriched in methanogens. The mire microbial network was modular with module cores consisting of clusters ofAcidobacteria, Euryarchaeota,orXanthomonodales.Loss of underlying permafrost with associated hydrological shifts correlated to changes in microbial composition, alpha, beta, and phylogenetic diversity associated with a higher radiative forcing signature. These results support the complex role of microbial interactions in mediating carbon budget changes and climate feedback in response to climate forcing.

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Large carbon cycle sensitivities to climate across a permafrost thaw gradient in subarctic Sweden

The Cryosphere ◽

10.5194/tc-13-647-2019 ◽

2019 ◽

Vol 13 (2) ◽

pp. 647-663 ◽

Cited By ~ 6

Author(s):

Kuang-Yu Chang ◽

William J. Riley ◽

Patrick M. Crill ◽

Robert F. Grant ◽

Virginia I. Rich ◽

...

Keyword(s):

Carbon Cycle ◽

Water Table ◽

Active Layer ◽

Carbon Budget ◽

Climate Forcing ◽

Biogeochemical Model ◽

Ch4 Emissions ◽

Permafrost Thaw ◽

Thawing Permafrost ◽

Subarctic Sweden

Abstract. Permafrost peatlands store large amounts of carbon potentially vulnerable to decomposition. However, the fate of that carbon in a changing climate remains uncertain in models due to complex interactions among hydrological, biogeochemical, microbial, and plant processes. In this study, we estimated effects of climate forcing biases present in global climate reanalysis products on carbon cycle predictions at a thawing permafrost peatland in subarctic Sweden. The analysis was conducted with a comprehensive biogeochemical model (ecosys) across a permafrost thaw gradient encompassing intact permafrost palsa with an ice core and a shallow active layer, partly thawed bog with a deeper active layer and a variable water table, and fen with a water table close to the surface, each with distinct vegetation and microbiota. Using in situ observations to correct local cold and wet biases found in the Global Soil Wetness Project Phase 3 (GSWP3) climate reanalysis forcing, we demonstrate good model performance by comparing predicted and observed carbon dioxide (CO2) and methane (CH4) exchanges, thaw depth, and water table depth. The simulations driven by the bias-corrected climate suggest that the three peatland types currently accumulate carbon from the atmosphere, although the bog and fen sites can have annual positive radiative forcing impacts due to their higher CH4 emissions. Our simulations indicate that projected precipitation increases could accelerate CH4 emissions from the palsa area, even without further degradation of palsa permafrost. The GSWP3 cold and wet biases for this site significantly alter simulation results and lead to erroneous active layer depth (ALD) and carbon budget estimates. Biases in simulated CO2 and CH4 exchanges from biased climate forcing are as large as those among the thaw stages themselves at a landscape scale across the examined permafrost thaw gradient. Future studies should thus not only focus on changes in carbon budget associated with morphological changes in thawing permafrost, but also recognize the effects of climate forcing uncertainty on carbon cycling.

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Increased nitrous oxide emissions from Arctic peatlands after permafrost thaw

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1702902114 ◽

2017 ◽

Vol 114 (24) ◽

pp. 6238-6243 ◽

Cited By ~ 53

Author(s):

Carolina Voigt ◽

Maija E. Marushchak ◽

Richard E. Lamprecht ◽

Marcin Jackowicz-Korczyński ◽

Amelie Lindgren ◽

...

Keyword(s):

Nitrous Oxide ◽

The Arctic ◽

Nitrous Oxide Emissions ◽

Emission Rates ◽

Carbon And Nitrogen ◽

Permafrost Thaw ◽

Arctic Soils ◽

Carbon Release ◽

Bare Peat ◽

Permafrost Thawing

Permafrost in the Arctic is thawing, exposing large carbon and nitrogen stocks for decomposition. Gaseous carbon release from Arctic soils due to permafrost thawing is known to be substantial, but growing evidence suggests that Arctic soils may also be relevant sources of nitrous oxide (N2O). Here we show that N2O emissions from subarctic peatlands increase as the permafrost thaws. In our study, the highest postthaw emissions occurred from bare peat surfaces, a typical landform in permafrost peatlands, where permafrost thaw caused a fivefold increase in emissions (0.56 ± 0.11 vs. 2.81 ± 0.6 mg N2O m−2 d−1). These emission rates match those from tropical forest soils, the world’s largest natural terrestrial N2O source. The presence of vegetation, known to limit N2O emissions in tundra, did decrease (by ∼90%) but did not prevent thaw-induced N2O release, whereas waterlogged conditions suppressed the emissions. We show that regions with high probability for N2O emissions cover one-fourth of the Arctic. Our results imply that the Arctic N2O budget will depend strongly on moisture changes, and that a gradual deepening of the active layer will create a strong noncarbon climate change feedback.

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Recent degradation of Interior Alaska permafrost mapped with ground surveys, geophysics, deep drilling, and repeat airborne LiDAR

10.5194/tc-2021-47 ◽

2021 ◽

Author(s):

Thomas A. Douglas ◽

Christopher A. Hiemstra ◽

John E. Anderson ◽

Robyn A. Barbato ◽

Kevin L. Bjella ◽

...

Keyword(s):

Active Layer ◽

Climate Warming ◽

Airborne Lidar ◽

The Arctic ◽

Permafrost Degradation ◽

Top Down ◽

Bottom Up ◽

Near Surface ◽

Permafrost Thaw ◽

Tussock Tundra

Abstract. Permafrost underlies one quarter of the northern hemisphere but is at increasing risk of thaw from climate warming. Recent studies across the Arctic have identified areas of rapid permafrost degradation from both top-down and lateral thaw. Of particular concern is thawing of ice rich high carbon content syngenetic yedoma permafrost like much of the permafrost in the region around Fairbanks, Alaska. With a mean annual temperature of −2 °C subtle differences in ecotype and permafrost ice and soil content control the near-surface permafrost thermal regime. Long-term measurements of the seasonally thawed active layer across central Alaska have identified an increase in permafrost thaw degradation that is expected to continue, and even accelerate, in coming decades. A major knowledge gap is relating belowground measurements of seasonal thaw, permafrost characteristics, and talik development with aboveground ecotype properties and thermokarst expansion that can readily quantify vegetation cover and track surface elevation changes over time. This study was conducted from 2013–2020 along four 400 to 500 m long transects near Fairbanks, Alaska. Repeat end of season active layer depths, near-surface permafrost temperature measurements, electrical resistivity tomography (ERT), deep (> 5 m) boreholes, and repeat airborne LiDAR were used to measure top down thaw and map thermokarst development at the sites. Our study confirms previous work using ERT to map surface thawed zones, however, our deep boreholes confirm the boundaries between frozen and thawed zones that are needed to model top down, lateral, and bottom-up thaw. At disturbed sites seasonal thaw increased up to 25 % between mid-August and early October and suggests active layer depths must be made as late in the fall season as possible because the projected increase in the summer season of just a few weeks could lead to significant additional thaw. At our sites, tussock tundra and spruce forest are associated with the lowest mean annual near-surface permafrost temperatures while mixed forest ecotypes are the warmest and exhibit the highest degree of recent temperature warming and thaw degradation. Thermokarst features and perennially thawed zones (taliks) have been identified at all sites. Our measurements, when combined with longer-term records from yedoma across the 500,000 km2 area of central Alaska show widespread initiation of near-surface permafrost thaw since roughly 2010. Using this partial area of the yedoma domain and projecting our thaw depth increases, by ecotype, across this domain we calculate 0.44 Gt of permafrost soil C have been thawed over the 7 year period, an amount equal to the yearly CO2 emissions of Australia. Since the yedoma permafrost and the variety of ecotypes at our sites represent much of the Arctic and subarctic land cover this study shows remote sensing measurements, top-down and bottom-up thermal modelling, and ground based surveys can be used predictively to identify areas of highest risk for permafrost thaw from projected future climate warming.

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Recent degradation of interior Alaska permafrost mapped with ground surveys, geophysics, deep drilling, and repeat airborne lidar

The Cryosphere ◽

10.5194/tc-15-3555-2021 ◽

2021 ◽

Vol 15 (8) ◽

pp. 3555-3575

Author(s):

Thomas A. Douglas ◽

Christopher A. Hiemstra ◽

John E. Anderson ◽

Robyn A. Barbato ◽

Kevin L. Bjella ◽

...

Keyword(s):

Active Layer ◽

Climate Warming ◽

Airborne Lidar ◽

The Arctic ◽

Permafrost Degradation ◽

Top Down ◽

Bottom Up ◽

Near Surface ◽

Permafrost Thaw ◽

Tussock Tundra

Abstract. Permafrost underlies one-quarter of the Northern Hemisphere but is at increasing risk of thaw from climate warming. Recent studies across the Arctic have identified areas of rapid permafrost degradation from both top-down and lateral thaw. Of particular concern is thawing syngenetic “yedoma” permafrost which is ice-rich and has a high carbon content. This type of permafrost is common in the region around Fairbanks, Alaska, and across central Alaska expanding westward to the Seward Peninsula. A major knowledge gap is relating belowground measurements of seasonal thaw, permafrost characteristics, and residual thaw layer development with aboveground ecotype properties and thermokarst expansion that can readily quantify vegetation cover and track surface elevation changes over time. This study was conducted from 2013 to 2020 along four 400 to 500 m long transects near Fairbanks, Alaska. Repeat active layer depths, near-surface permafrost temperature measurements, electrical resistivity tomography (ERT), deep (> 5 m) boreholes, and repeat airborne light detection and ranging (lidar) were used to measure top-down permafrost thaw and map thermokarst development at the sites. Our study confirms previous work using ERT to map surface thawed zones; however, our deep boreholes confirm the boundaries between frozen and thawed zones that are needed to model top-down, lateral, and bottom-up thaw. At disturbed sites seasonal thaw increased up to 25 % between mid-August and early October and suggests measurements to evaluate active layer depth must be made as late in the fall season as possible because the projected increase in the summer season of just a few weeks could lead to significant additional thaw. At our sites, tussock tundra and spruce forest are associated with the lowest mean annual near-surface permafrost temperatures while mixed-forest ecotypes are the warmest and exhibit the highest degree of recent temperature warming and thaw degradation. Thermokarst features, residual thaw layers, and taliks have been identified at all sites. Our measurements, when combined with longer-term records from yedoma across the 500 000 km2 area of central Alaska, show widespread near-surface permafrost thaw since 2010. Projecting our thaw depth increases, by ecotype, across the yedoma domain, we calculate a first-order estimate that 0.44 Pg of organic carbon in permafrost soil has thawed over the past 7 years, which, for perspective, is an amount of carbon nearly equal to the yearly CO2 emissions of Australia. Since the yedoma permafrost and the variety of ecotypes at our sites represent much of the Arctic and subarctic land cover, this study shows remote sensing measurements, top-down and bottom-up thermal modeling, and ground-based surveys can be used predictively to identify areas of the highest risk for permafrost thaw from projected future climate warming.

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A Critical Zone Approach to Carbon Fluxes in the Arctic Tundra

10.5194/egusphere-egu2020-2956 ◽

2020 ◽

Author(s):

Mariasilvia Giamberini ◽

Ilaria Baneschi ◽

Matteo Lelli ◽

Marta Magnani ◽

Brunella Raco ◽

...

Keyword(s):

Active Layer ◽

Ecosystem Respiration ◽

Carbon Fluxes ◽

Arctic Tundra ◽

Critical Zone ◽

Climate Feedback ◽

The Arctic ◽

Svalbard Archipelago ◽

Accumulation Chamber ◽

Flux Data

Arctic tundra is currently undergoing significant changes induced by the effects of a rapid temperature rise, that in the Arctic is about twice as fast as in the rest of the world. The response of the system composed by the permafrost active layer, soil and vegetation is especially relevant. In fact, it is still unclear whether the system will turn from a carbon sink to a carbon source, owing to the interplay of two opposite phenomena: the increasing time span of the growing season, favouring Net Ecosystem Production (NEP), and the increasing soil temperatures, favouring degradation of organic matter through heterotrophic respiration (HR) and then creating a positive climate feedback. In this work, we analyse soil-vegetation-atmosphere CO2 flux data of a field campaign conducted in the Bayelva river basin, Spitzbergen, in the Svalbard Archipelago (NO) during summer 2019, measured by a portable accumulation chamber. We use a &#8220;Critical Zone&#8221; perspective, considering the multiple interactions between biotic and abiotic components. We measured the Net Ecosystem Exchange (NEE) and Ecosystem Respiration (ER) along a slope gradient at different degrees of soil humidity and active layer depths, relating flux data to climate and environmental parameters, soil physical-chemical parameters and vegetation type. The statistical empirical relationships between variables are analysed to identify the main drivers of carbon exchanges. An empirical data-driven model is built to describe the coupled dynamics of soil, vegetation, water and atmosphere that contributes to budgeting the carbon cycle in the Arctic Critical Zone. A comparison of the carbon fluxes obtained with the accumulation chamber method and an Eddy Covariance tower located in the same area is also addressed.

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Learning Soil Freeze Characteristic Curves with Universal Differential Equations

10.5194/egusphere-egu21-13409 ◽

2021 ◽

Author(s):

Brian Groenke ◽

Moritz Langer ◽

Guillermo Gallego ◽

Julia Boike

Keyword(s):

Differential Equations ◽

Phase Change ◽

Land Surface ◽

Large Scale ◽

Characteristic Curve ◽

Soil Freezing ◽

Climate Feedback ◽

The Arctic ◽

Permafrost Thaw

Permafrost thaw is considered one of the major climate feedback processes and is currently a significant source of uncertainty in predicting future climate states. Coverage of in-situ meteorological and land-surface observations is sparse throughout the Arctic, making it difficult to track the large-scale evolution of the Arctic surface and subsurface energy balance. Furthermore, permafrost thaw is a highly non-linear process with its own feedback mechanisms such as thermokarst and thermo-erosion. Land surface models, therefore, play an important role in our ability to understand how permafrost responds to the changing climate. There is also a need to quantify freeze-thaw cycling and the incomplete freezing of soil at depth (talik formation). One of the key difficulties in modeling the Arctic subsurface is the complexity of the thermal regime during phase change under freezing or thawing conditions. Modeling heat conduction with phase change accurately requires estimation of the soil freeze characteristic curve (SFCC) which governs the change in soil liquid water content with respect to temperature and depends on the soil physical characteristics (texture). In this work, we propose a method for replacing existing brute-force approximations of the SFCC in the CryoGrid 3 permafrost model with universal differential equations, i.e. differential equations that include one or more terms represented by a universal approximator (e.g. a neural network). The approximator is thus tasked with inferring a suitable SFCC from available soil temperature, moisture, and texture data. We also explore how remote sensing data might be used with universal approximators to extrapolate soil freezing characteristics where in-situ observations are not available.

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Large carbon cycle sensitivities to climate across a permafrost thaw gradient in subarctic Sweden

10.5194/tc-2018-215 ◽

2018 ◽

Author(s):

Kuang-Yu Chang ◽

William J. Riley ◽

Patrick Crill ◽

Robert F. Grant ◽

Virginia Rich ◽

...

Keyword(s):

Carbon Cycle ◽

Water Table ◽

Active Layer ◽

Carbon Budget ◽

Climate Forcing ◽

Biogeochemical Model ◽

Ch4 Emissions ◽

Permafrost Thaw ◽

Thawing Permafrost ◽

Subarctic Sweden

Abstract. Permafrost peatlands store large amounts of carbon potentially vulnerable to decomposition. However, the fate of that carbon in a changing climate remains uncertain in models due to complex interactions among hydrological, biogeochemical, microbial, and plant processes. In this study, we estimated effects of climate forcing biases present in global climate reanalysis products on carbon cycle predictions at a thawing permafrost peatland in subarctic Sweden. The analysis was conducted with a comprehensive biogeochemical model (ecosys) across a permafrost thaw gradient encompassing intact palsa with an ice core and a shallow active layer, partly thawed bog with a deeper active layer and a variable water table, and fully thawed fen with a water table close to the surface, each with distinct vegetation and microbiota. Using in situ observations to correct local cold and wet biases found in the Global Soil Wetness Project Phase 3 (GSWP3) climate reanalysis forcing, we evaluated our model performance by comparing predicted and observed carbon dioxide (CO2) and methane (CH4) exchanges, thaw depth, and water table depth. The simulations driven by the bias-corrected climate suggest that the three peatland types currently accumulate carbon from the atmosphere, although the bog and fen sites can have annual positive radiative forcing impacts due to their higher CH4 emissions. Our simulations indicate that projected precipitation increases could accelerate CH4 emissions from the palsa area, even without further degradation of palsa permafrost. The GSWP3 cold and wet biases for this site significantly alter simulation results and lead to erroneous active layer depth and carbon budget estimates. Biases in simulated CO2 and CH4 exchanges from biased climate forcing are as large as those among the thaw stages themselves at a landscape scale across the examined permafrost thaw gradient. Future studies should thus not only focus on changes in carbon budget associated with morphological changes in thawing permafrost, but also recognize the effects of climate forcing uncertainty on carbon cycling.

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Population living on permafrost in the Arctic

Population and Environment ◽

10.1007/s11111-020-00370-6 ◽

2021 ◽

Vol 43 (1) ◽

pp. 22-38

Author(s):

Justine Ramage ◽

Leneisja Jungsberg ◽

Shinan Wang ◽

Sebastian Westermann ◽

Hugues Lantuit ◽

...

Keyword(s):

The Arctic ◽

Permafrost Region ◽

Permafrost Thaw ◽

Arctic Regions ◽

High Hazard

AbstractPermafrost thaw is a challenge in many Arctic regions, one that modifies ecosystems and affects infrastructure and livelihoods. To date, there have been no demographic studies of the population on permafrost. We present the first estimates of the number of inhabitants on permafrost in the Arctic Circumpolar Permafrost Region (ACPR) and project changes as a result of permafrost thaw. We combine current and projected populations at settlement level with permafrost extent. Key findings indicate that there are 1162 permafrost settlements in the ACPR, accommodating 5 million inhabitants, of whom 1 million live along a coast. Climate-driven permafrost projections suggest that by 2050, 42% of the permafrost settlements will become permafrost-free due to thawing. Among the settlements remaining on permafrost, 42% are in high hazard zones, where the consequences of permafrost thaw will be most severe. In total, 3.3 million people in the ACPR live currently in settlements where permafrost will degrade and ultimately disappear by 2050.

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Geophysical imaging of permafrost in the SW Svalbard – the result of two high arctic expeditions to Spitsbergen

10.5194/egusphere-egu2020-8136 ◽

2020 ◽

Author(s):

Mariusz Majdanski ◽

Artur Marciniak ◽

Bartosz Owoc ◽

Wojciech Dobiński ◽

Tomasz Wawrzyniak ◽

...

Keyword(s):

Surface Waves ◽

Active Layer ◽

High Arctic ◽

The Arctic ◽

Seismic Profiles ◽

Frozen Ground ◽

Near Surface ◽

Seismic Processing ◽

Reflection Seismic ◽

Sea Coast

The Arctic regions are the place of the fastest observed climate change. One of the indicators of such evolution are changes occurring in the glaciers and the subsurface in the permafrost. The active layer of the permafrost as the shallowest one is well measured by multiple geophysical techniques and in-situ measurements.Two high arctic expeditions have been organized to use seismic methods to recognize the shape of the permafrost in two seasons: with the unfrozen ground (October 2017) and frozen ground (April 2018). Two seismic profiles have been designed to visualize the shape of permafrost between the sea coast and the slope of the mountain, and at the front of a retreating glacier. For measurements, a stand-alone seismic stations has been used with accelerated weight drop with in-house modifications and timing system. Seismic profiles were acquired in a time-lapse manner and were supported with GPR and ERT measurements, and continuous temperature monitoring in shallow boreholes.Joint interpretation of seismic and auxiliary data using Multichannel analysis of surface waves, First arrival travel-time tomography and Reflection imaging show clear seasonal changes affecting the active layer where P-wave velocities are changing from 3500 to 5200 m/s. This confirms the laboratory measurements showing doubling the seismic velocity of water-filled high-porosity rocks when frozen. The same laboratory study shows significant (>10%) increase of velocity in frozen low porosity rocks, that should be easily visible in seismic.In the reflection seismic processing, the most critical part was a detailed front mute to eliminate refracted arrivals spoiling wide-angle near-surface reflections. Those long offset refractions were however used to estimate near-surface velocities further used in reflection processing. In the reflection seismic image, a horizontal reflection was traced at the depth of 120 m at the sea coast deepening to the depth of 300 m near the mountain.Additionally, an optimal set of seismic parameters has been established, clearly showing a significantly higher signal to noise ratio in case of frozen ground conditions even with the snow cover. Moreover, logistics in the frozen conditions are much easier and a lack of surface waves recorded in the snow buried geophones makes the seismic processing simpler.Acknowledgements&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160;This research was funded by the National Science Centre, Poland (NCN) Grant UMO-2015/21/B/ST10/02509.

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