Earth and Planetary Sciences › Atmospheric Science

Climate change and permafrost

Works Count: 55632

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Description

This cluster of papers focuses on the dynamics of Arctic permafrost in the context of climate change, including its impact on carbon feedback, methane emissions, vegetation change, and hydrology. The research covers a wide range of topics such as soil organic carbon pools, shrub expansion, tundra biome responses, and the vulnerability of high-latitude soil organic carbon.

Keywords

Permafrost; Arctic; Climate Change; Carbon Feedback; Thawing; Methane Emissions; Tundra; Vegetation Change; Hydrology; Ecosystem Response

Increasing shrub abundance in the Arctic

2001-05-01

Matthew Sturm , Charles H. Racine , K. D. Tape

Permafrost and the Global Carbon Budget

2006-06-15

S. A. Zimov , Edward A. G. Schuur , F. Stuart Chapin

Climate warming will thaw permafrost, releasing trapped carbon from this high-latitude reservoir and further exacerbating global warming. Climate warming will thaw permafrost, releasing trapped carbon from this high-latitude reservoir and further exacerbating global warming.

Circum-Arctic map of permafrost and ground-ice conditions

1997-01-01

James P Brown , Oscar J. Ferrians , J A Heginbottom +1 more

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Arctic Climate Impact Assessment

2017-01-01

C. Symon , Lelani Arris , Bill Heal +1 more

The dominant role of semi-arid ecosystems in the trend and variability of the land CO <sub>2</sub> sink

2015-05-22

Anders Ahlström , Michael Raupach , Guy Schurgers +7 more

The difference is found at the margins The terrestrial biosphere absorbs about a quarter of all anthropogenic carbon dioxide emissions, but the amount that they take up varies from year … The difference is found at the margins The terrestrial biosphere absorbs about a quarter of all anthropogenic carbon dioxide emissions, but the amount that they take up varies from year to year. Why? Combining models and observations, Ahlström et al. found that marginal ecosystems—semiarid savannas and low-latitude shrublands—are responsible for most of the variability. Biological productivity in these semiarid regions is water-limited and strongly associated with variations in precipitation, unlike wetter tropical areas. Understanding carbon uptake by these marginal lands may help to improve predictions of variations in the global carbon cycle. Science , this issue p. 895

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Soil organic carbon pools in the northern circumpolar permafrost region

2009-06-01

C. Tarnocai , Josep G. Canadell , Edward A. G. Schuur +3 more

The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern … The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern permafrost region is approximately 18,782 × 10 3 km 2 , or approximately 16% of the global soil area. In the northern permafrost region, organic soils (peatlands) and cryoturbated permafrost‐affected mineral soils have the highest mean soil organic carbon contents (32.2–69.6 kg m −2 ). Here we report a new estimate of the carbon pools in soils of the northern permafrost region, including deeper layers and pools not accounted for in previous analyses. Carbon pools were estimated to be 191.29 Pg for the 0–30 cm depth, 495.80 Pg for the 0–100 cm depth, and 1024.00 Pg for the 0–300 cm depth. Our estimate for the first meter of soil alone is about double that reported for this region in previous analyses. Carbon pools in layers deeper than 300 cm were estimated to be 407 Pg in yedoma deposits and 241 Pg in deltaic deposits. In total, the northern permafrost region contains approximately 1672 Pg of organic carbon, of which approximately 1466 Pg, or 88%, occurs in perennially frozen soils and deposits. This 1672 Pg of organic carbon would account for approximately 50% of the estimated global belowground organic carbon pool.

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Temperature and Plant Species Control Over Litter Decomposition in Alaskan Tundra

1996-11-01

Sarah E. Hobbie

I compared effects of increased temperature and litter from different Alaskan tundra plant species on cycling of carbon and nitrogen through litter and soil in microcosms. Warming between 4 ° … I compared effects of increased temperature and litter from different Alaskan tundra plant species on cycling of carbon and nitrogen through litter and soil in microcosms. Warming between 4 ° and 10 ° C significantly increased rates of soil and litter respiration, litter decomposition, litter nitrogen release, and soil net nitrogen mineralization. Thus, future warming will directly increase rates of carbon and nitrogen cycling through litter and soil in tundra. In addition, differences among species' litter in rates of decomposition, N release, and effects on soil net nitrogen mineralization were sometimes larger than differences between the two temperature treatments within a species. Thus, changes in plant community structure and composition associated with future warming will have important consequences for how elements cycle through litter and soil in tundra. In general, species within a growth form (graminoids, evergreen shrubs, deciduous shrubs, and mosses) were more similar in their effects on decomposition than were species belonging to different growth forms, with graminoid litter having the fastest rate and litter of deciduous shrubs and mosses having the slowest rates. Differences in rates of litter decomposition were more related to carbon quality than to nitrogen concentration. Increased abundance of deciduous shrubs with future climate warming will promote carbon storage, because of their relatively large allocation to woody stems that decompose slowly. Changes in moss abundance will also have important consequences for future carbon and nitrogen cycling, since moss litter is extremely recalcitrant and has a low potential to immobilize nitrogen.

Responses of Arctic Tundra to Experimental and Observed Changes in Climate

1995-04-01

F. Stuart Chapin , Gaius R. Shaver , Anne E. Giblin +2 more

We manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes in these parameters might affect community and ecosystem processes. Some of … We manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes in these parameters might affect community and ecosystem processes. Some of these manipulations altered nutrient availability, growth—form composition, net primary production, and species richness in less than a decade, indicating that arctic vegetation at this site is sensitive to climatic change. In general, short—term (3—yr) responses were poor predictors of longer term (9—yr) changes in community composition. The longer term responses showed closer correspondence to patterns of vegetation distribution along environmental gradients. Nitrogen and phosphorus availability tended to increase in response to elevated temperature, reflecting increased mineralization, and in response to light attenuation, reflecting reduced nutrient uptake by vegetation. Nutrient addition increased biomass and production of deciduous shrubs but reduced growth of evergreen shrubs and nonvascular plants. Light attenuation reduced biomass of all growth forms. Elevated temperature enhanced shrub production but reduced production of nonvascular plants. These contrasting responses to temperature increase and to nutrient addition by different growth forms "canceled out" at the ecosystem level, buffering changes in ecosystem characteristics such as biomass, production, and nutrient uptake. The major effect of elevated temperature was to speed plant response to changes in soil resources and, in the long term (9 yr), to increase nutrient availability through changes in N mineralization. Species within a growth form were similar to one another in their responses to changes in resources (light or nutrients) but showed no consistent response to evelated temperature. Species richness was reduced 30—50% by temperature and nutrient treatments, due to loss of less abundant species. Declines in diversity occurred disproportionately in forbs, which are important for animal nutrition, and in mosses, which maintain soil thermal regime. There was no increased abundance of initially rare species in response to any treatment. During our 9—yr study (the warmest decade on record in the region), biomass of one dominant tundra species unexpectedly changed in control plots in the direction predicted by our experiments and by Holocene pollen records. This suggests that regional climatic warming may already be altering the species composition of Alaskan arctic tundra.

Improvements to the Community Land Model and their impact on the hydrological cycle

2008-03-01

Keith W. Oleson , Guo‐Yue Niu , Zong‐Liang Yang +7 more

The Community Land Model version 3 (CLM3) is the land component of the Community Climate System Model (CCSM). CLM3 has energy and water biases resulting from deficiencies in some of … The Community Land Model version 3 (CLM3) is the land component of the Community Climate System Model (CCSM). CLM3 has energy and water biases resulting from deficiencies in some of its canopy and soil parameterizations related to hydrological processes. Recent research by the community that utilizes CLM3 and the family of CCSM models has indicated several promising approaches to alleviating these biases. This paper describes the implementation of a selected set of these parameterizations and their effects on the simulated hydrological cycle. The modifications consist of surface data sets based on Moderate Resolution Imaging Spectroradiometer products, new parameterizations for canopy integration, canopy interception, frozen soil, soil water availability, and soil evaporation, a TOPMODEL‐based model for surface and subsurface runoff, a groundwater model for determining water table depth, and the introduction of a factor to simulate nitrogen limitation on plant productivity. The results from a set of offline simulations were compared with observed data for runoff, river discharge, soil moisture, and total water storage to assess the performance of the new model (referred to as CLM3.5). CLM3.5 exhibits significant improvements in its partitioning of global evapotranspiration (ET) which result in wetter soils, less plant water stress, increased transpiration and photosynthesis, and an improved annual cycle of total water storage. Phase and amplitude of the runoff annual cycle is generally improved. Dramatic improvements in vegetation biogeography result when CLM3.5 is coupled to a dynamic global vegetation model. Lower than observed soil moisture variability in the rooting zone is noted as a remaining deficiency.

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Disappearing Arctic Lakes

2005-06-02

L. C. Smith , Yongwei Sheng , Glen M. MacDonald +1 more

Historical archived satellite images were compared with contemporary satellite data to track ongoing changes in more than 10,000 large lakes in rapidly warming Siberia. A widespread decline in lake abundance … Historical archived satellite images were compared with contemporary satellite data to track ongoing changes in more than 10,000 large lakes in rapidly warming Siberia. A widespread decline in lake abundance and area has occurred since 1973, despite slight precipitation increases to the region. The spatial pattern of lake disappearance suggests (i) that thaw and "breaching" of permafrost is driving the observed losses, by enabling rapid lake draining into the subsurface; and (ii) a conceptual model in which high-latitude warming of permafrost triggers an initial but transitory phase of lake and wetland expansion, followed by their widespread disappearance.

RESPONSES OF TUNDRA PLANTS TO EXPERIMENTAL WARMING:META-ANALYSIS OF THE INTERNATIONAL TUNDRA EXPERIMENT

1999-11-01

Anna M. Arft , Marilyn D. Walker , Jessica Gurevitch +7 more

The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX … The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX was designed specifically to examine variability in arctic and alpine species response to increased temperature. We compiled from one to four years of experimental data from 13 different ITEX sites and used meta-analysis to analyze responses of plant phenology, growth, and reproduction to experimental warming. Results indicate that key phenological events such as leaf bud burst and flowering occurred earlier in warmed plots throughout the study period; however, there was little impact on growth cessation at the end of the season. Quantitative measures of vegetative growth were greatest in warmed plots in the early years of the experiment, whereas reproductive effort and success increased in later years. A shift away from vegetative growth and toward reproductive effort and success in the fourth treatment year suggests a shift from the initial response to a secondary response. The change in vegetative response may be due to depletion of stored plant reserves, whereas the lag in reproductive response may be due to the formation of flower buds one to several seasons prior to flowering. Both vegetative and reproductive responses varied among life-forms; herbaceous forms had stronger and more consistent vegetative growth responses than did woody forms. The greater responsiveness of the herbaceous forms may be attributed to their more flexible morphology and to their relatively greater proportion of stored plant reserves. Finally, warmer, low arctic sites produced the strongest growth responses, but colder sites produced a greater reproductive response. Greater resource investment in vegetative growth may be a conservative strategy in the Low Arctic, where there is more competition for light, nutrients, or water, and there may be little opportunity for successful germination or seedling development. In contrast, in the High Arctic, heavy investment in producing seed under a higher temperature scenario may provide an opportunity for species to colonize patches of unvegetated ground. The observed differential response to warming suggests that the primary forces driving the response vary across climatic zones, functional groups, and through time.

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Climate change and the permafrost carbon feedback

2015-04-01

Edward A. G. Schuur , A. David McGuire , Christina Schädel +7 more

Plot-scale evidence of tundra vegetation change and links to recent summer warming

2012-04-05

Sarah C. Elmendorf , Gregory H. R. Henry , Robert D. Hollister +7 more

The effect of permafrost thaw on old carbon release and net carbon exchange from tundra

2009-05-01

Edward A. G. Schuur , Jason G. Vogel , Kathryn G. Crummer +3 more

DAYCENT and its land surface submodel: description and testing

1998-12-01

William J. Parton , Melannie D. Hartman , Dennis S. Ojima +1 more

Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization

2004-09-01

Michelle C. Mack , Edward A. G. Schuur , M. Syndonia Bret‐Harte +2 more

The Common Land Model

2003-08-01

Yongjiu Dai , Xubin Zeng , Robert E. Dickinson +7 more

The Common Land Model (CLM) was developed for community use by a grassroots collaboration of scientists who have an interest in making a general land model available for public use … The Common Land Model (CLM) was developed for community use by a grassroots collaboration of scientists who have an interest in making a general land model available for public use and further development. The major model characteristics include enough unevenly spaced layers to adequately represent soil temperature and soil moisture, and a multilayer parameterization of snow processes; an explicit treatment of the mass of liquid water and ice water and their phase change within the snow and soil system; a runoff parameterization following the TOPMODEL concept; a canopy photo synthesis-conductance model that describes the simultaneous transfer of CO2 and water vapor into and out of vegetation; and a tiled treatment of the subgrid fraction of energy and water balance. CLM has been extensively evaluated in offline mode and coupling runs with the NCAR Community Climate Model (CCM3). The results of two offline runs, presented as examples, are compared with observations and with the simulation of three other land models [the Biosphere-Atmosphere Transfer Scheme (BATS), Bonan's Land Surface Model (LSM), and the 1994 version of the Chinese Academy of Sciences Institute of Atmospheric Physics LSM (IAP94)].

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Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming

2006-09-01

K. M. Walter , S. A. Zimov , Jeffrey P. Chanton +2 more

Shifts in Arctic vegetation and associated feedbacks under climate change

2013-03-31

Richard G. Pearson , Steven J. Phillips , M. M. Loranty +4 more

Abrupt increase in permafrost degradation in Arctic Alaska

2006-01-01

M. Torre Jorgenson , Y. Shur , Erik R. Pullman

Even though the arctic zone of continuous permafrost has relatively cold mean annual air temperatures, we found an abrupt, large increase in the extent of permafrost degradation in northern Alaska … Even though the arctic zone of continuous permafrost has relatively cold mean annual air temperatures, we found an abrupt, large increase in the extent of permafrost degradation in northern Alaska since 1982, associated with record warm temperatures during 1989–1998. Our field studies revealed that the recent degradation has mainly occurred to massive wedges of ice that previously had been stable for 1000s of years. Analysis of airphotos from 1945, 1982, and 2001 revealed large increases in the area (0.5%, 0.6%, and 4.4% of area, respectively) and density (88, 128, and 1336 pits/km 2 ) of degrading ice wedges in two study areas on the arctic coastal plain. Spectral analysis across a broader landscape found that newly degraded, water‐filled pits covered 3.8% of the land area. These results indicate that thermokarst potentially can affect 10–30% of arctic lowland landscapes and severely alter tundra ecosystems even under scenarios of modest climate warming.

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Permafrost thermal state in the polar Northern Hemisphere during the international polar year 2007–2009: a synthesis

2010-04-01

V. E. Romanovsky , Sharon L. Smith , Hanne H. Christiansen

Abstract The permafrost monitoring network in the polar regions of the Northern Hemisphere was enhanced during the International Polar Year (IPY), and new information on permafrost thermal state was collected … Abstract The permafrost monitoring network in the polar regions of the Northern Hemisphere was enhanced during the International Polar Year (IPY), and new information on permafrost thermal state was collected for regions where there was little available. This augmented monitoring network is an important legacy of the IPY, as is the updated baseline of current permafrost conditions against which future changes may be measured. Within the Northern Hemisphere polar region, ground temperatures are currently being measured in about 575 boreholes in North America, the Nordic region and Russia. These show that in the discontinuous permafrost zone, permafrost temperatures fall within a narrow range, with the mean annual ground temperature (MAGT) at most sites being higher than −2°C. A greater range in MAGT is present within the continuous permafrost zone, from above −1°C at some locations to as low as −15°C. The latest results indicate that the permafrost warming which started two to three decades ago has generally continued into the IPY period. Warming rates are much smaller for permafrost already at temperatures close to 0°C compared with colder permafrost, especially for ice‐rich permafrost where latent heat effects dominate the ground thermal regime. Colder permafrost sites are warming more rapidly. This improved knowledge about the permafrost thermal state and its dynamics is important for multidisciplinary polar research, but also for many of the 4 million people living in the Arctic. In particular, this knowledge is required for designing effective adaptation strategies for the local communities under warmer climatic conditions. Copyright © 2010 John Wiley & Sons, Ltd.

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Permafrost carbon-climate feedbacks accelerate global warming

2011-08-18

Charles D. Koven , Bruno Ringeval , Pierre Friedlingstein +5 more

Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a … Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a terrestrial ecosystem model that includes permafrost carbon dynamics, inhibition of respiration in frozen soil layers, vertical mixing of soil carbon from surface to permafrost layers, and CH 4 emissions from flooded areas, and which better matches new circumpolar inventories of soil carbon stocks, to explore the potential for carbon-climate feedbacks at high latitudes. Contrary to model results for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), when permafrost processes are included, terrestrial ecosystems north of 60°N could shift from being a sink to a source of CO 2 by the end of the 21st century when forced by a Special Report on Emissions Scenarios (SRES) A2 climate change scenario. Between 1860 and 2100, the model response to combined CO 2 fertilization and climate change changes from a sink of 68 Pg to a 27 + -7 Pg sink to 4 + -18 Pg source, depending on the processes and parameter values used. The integrated change in carbon due to climate change shifts from near zero, which is within the range of previous model estimates, to a climate-induced loss of carbon by ecosystems in the range of 25 + -3 to 85 + -16 Pg C, depending on processes included in the model, with a best estimate of a 62 + -7 Pg C loss. Methane emissions from high-latitude regions are calculated to increase from 34 Tg CH 4 /y to 41–70 Tg CH 4 /y, with increases due to CO 2 fertilization, permafrost thaw, and warming-induced increased CH 4 flux densities partially offset by a reduction in wetland extent.

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Recent change of Arctic tundra ecosystems from a net carbon dioxide sink to a source

1993-02-01

Walter C. Oechel , Steven J. Hastings , George Vourlrtis +3 more

Class—A Canadian land surface scheme for GCMS. I. Soil model

1991-03-01

Diana Verseghy

Abstract A new GCM land surface scheme is introduced, incorporating three soil layers with physically based calculations of heat and moisture transfers at the surface and across the layer boundaries. … Abstract A new GCM land surface scheme is introduced, incorporating three soil layers with physically based calculations of heat and moisture transfers at the surface and across the layer boundaries. Snow‐covered and snow‐free areas are treated separately. The energy balance equation is solved iteratively for the surface temperature; the surface infiltration rate is calculated using a simplified theoretical analysis allowing for surface ponding. Snow cover is modelled as a discrete ‘soil’ layer. The results generated by CLASS are compared with those of an older model incorporating the force‐restore method for the calculation of surface temperature and a bucket‐type formulation for the ground moisture. Several month‐long test runs are carried out in stand‐alone mode. It is shown that the surface temperature in the old scheme responds more slowly to diurnal forcing and more quickly to longer term forcing than that modelled by CLASS, while its one‐layer representation of soil moisture proves incapable of reproducing changes in the surface fluxes owing to surface variations of moisture content. Finally, the lumped treatment of snow and soil in the old scheme results in an extremely fast disappearance of the snow pack under certain conditions.

Changing Climate: Geothermal Evidence from Permafrost in the Alaskan Arctic

1986-11-07

Arthur H. Lachenbruch , B.V. Marshall

Temperature profiles measured in permafrost in northernmost Alaska usually have anomalous curvature in the upper 100 meters or so. When analyzed by heat-conduction theory, the profiles indicate a variable but … Temperature profiles measured in permafrost in northernmost Alaska usually have anomalous curvature in the upper 100 meters or so. When analyzed by heat-conduction theory, the profiles indicate a variable but widespread secular warming of the permafrost surface, generally in the range of 2 to 4 Celsius degrees during the last few decades to a century. Although details of the climatic change cannot be resolved with existing data, there is little doubt of its general magnitude and timing; alternative explanations are limited by the fact that heat transfer in cold permafrost is exclusively by conduction. Since models of greenhouse warming predict climatic change will be greatest in the Arctic and might already be in progress, it is prudent to attempt to understand the rapidly changing thermal regime in this region.

Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps

2014-12-01

Gustaf Hugelius , Jens Strauß , Sebastian Zubrzycki +7 more

Abstract. Soils and other unconsolidated deposits in the northern circumpolar permafrost region store large amounts of soil organic carbon (SOC). This SOC is potentially vulnerable to remobilization following soil warming … Abstract. Soils and other unconsolidated deposits in the northern circumpolar permafrost region store large amounts of soil organic carbon (SOC). This SOC is potentially vulnerable to remobilization following soil warming and permafrost thaw, but SOC stock estimates were poorly constrained and quantitative error estimates were lacking. This study presents revised estimates of permafrost SOC stocks, including quantitative uncertainty estimates, in the 0–3 m depth range in soils as well as for sediments deeper than 3 m in deltaic deposits of major rivers and in the Yedoma region of Siberia and Alaska. Revised estimates are based on significantly larger databases compared to previous studies. Despite this there is evidence of significant remaining regional data gaps. Estimates remain particularly poorly constrained for soils in the High Arctic region and physiographic regions with thin sedimentary overburden (mountains, highlands and plateaus) as well as for deposits below 3 m depth in deltas and the Yedoma region. While some components of the revised SOC stocks are similar in magnitude to those previously reported for this region, there are substantial differences in other components, including the fraction of perennially frozen SOC. Upscaled based on regional soil maps, estimated permafrost region SOC stocks are 217 ± 12 and 472 ± 27 Pg for the 0–0.3 and 0–1 m soil depths, respectively (±95% confidence intervals). Storage of SOC in 0–3 m of soils is estimated to 1035 ± 150 Pg. Of this, 34 ± 16 Pg C is stored in poorly developed soils of the High Arctic. Based on generalized calculations, storage of SOC below 3 m of surface soils in deltaic alluvium of major Arctic rivers is estimated as 91 ± 52 Pg. In the Yedoma region, estimated SOC stocks below 3 m depth are 181 ± 54 Pg, of which 74 ± 20 Pg is stored in intact Yedoma (late Pleistocene ice- and organic-rich silty sediments) with the remainder in refrozen thermokarst deposits. Total estimated SOC storage for the permafrost region is ∼1300 Pg with an uncertainty range of ∼1100 to 1500 Pg. Of this, ∼500 Pg is in non-permafrost soils, seasonally thawed in the active layer or in deeper taliks, while ∼800 Pg is perennially frozen. This represents a substantial ∼300 Pg lowering of the estimated perennially frozen SOC stock compared to previous estimates.

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Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities

2011-12-01

Isla H. Myers‐Smith , Bruce C. Forbes , Martin Wilmking +7 more

Abstract Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present … Abstract Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of investigation for future research. Satellite observations from around the circumpolar Arctic, showing increased productivity, measured as changes in ‘greenness’, have coincided with a general rise in high-latitude air temperatures and have been partly attributed to increases in shrub cover. Studies indicate that warming temperatures, changes in snow cover, altered disturbance regimes as a result of permafrost thaw, tundra fires, and anthropogenic activities or changes in herbivory intensity are all contributing to observed changes in shrub abundance. A large-scale increase in shrub cover will change the structure of tundra ecosystems and alter energy fluxes, regional climate, soil–atmosphere exchange of water, carbon and nutrients, and ecological interactions between species. In order to project future rates of shrub expansion and understand the feedbacks to ecosystem and climate processes, future research should investigate the species or trait-specific responses of shrubs to climate change including: (1) the temperature sensitivity of shrub growth, (2) factors controlling the recruitment of new individuals, and (3) the relative influence of the positive and negative feedbacks involved in shrub expansion.

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Increasing River Discharge to the Arctic Ocean

2002-12-12

Bruce J. Peterson , R. M. Holmes , J. W. McClelland +5 more

Synthesis of river-monitoring data reveals that the average annual discharge of fresh water from the six largest Eurasian rivers to the Arctic Ocean increased by 7% from 1936 to 1999. … Synthesis of river-monitoring data reveals that the average annual discharge of fresh water from the six largest Eurasian rivers to the Arctic Ocean increased by 7% from 1936 to 1999. The average annual rate of increase was 2.0 +/- 0.7 cubic kilometers per year. Consequently, average annual discharge from the six rivers is now about 128 cubic kilometers per year greater than it was when routine measurements of discharge began. Discharge was correlated with changes in both the North Atlantic Oscillation and global mean surface air temperature. The observed large-scale change in freshwater flux has potentially important implications for ocean circulation and climate.

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A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming

2001-02-01

Lindsey E. Rustad , John L. Campbell , G. M. Marion +5 more

Lakes and reservoirs as regulators of carbon cycling and climate

2009-11-01

Lars J. Tranvik , John Downing , James B. Cotner +7 more

We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in … We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.

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Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions

2005-10-01

L. D. Hinzman , Neil D. Bettez , William Bolton +7 more

Responses of permafrost to climate change and their environmental significance, Qinghai‐Tibet Plateau

2007-06-01

Guodong Cheng , Tonghua Wu

In this paper we summarize recent research in geocryological studies carried out on the Qinghai‐Tibet Plateau that show responses of permafrost to climate change and their environmental implications. Long‐term temperature … In this paper we summarize recent research in geocryological studies carried out on the Qinghai‐Tibet Plateau that show responses of permafrost to climate change and their environmental implications. Long‐term temperature measurements indicate that the lower altitudinal limit of permafrost has moved up by 25 m in the north during the last 30 years and between 50 and 80 m in the south over the last 20 years. Furthermore, the thickness of the active layer has increased by 0.15 to 0.50 m and ground temperature at a depth of 6 m has risen by about 0.1° to 0.3°C between 1996 and 2001. Recent studies show that freeze‐thaw cycles in the ground intensify the heat exchange between the atmosphere and the ground surface. The greater the moisture content in the soil, the greater is the influence of freeze‐thaw cycling on heat exchange. The water and heat exchange between the atmosphere and the ground surface due to soil freezing and thawing has a significant influence on the climate in eastern Asia. A negative correlation exists between soil moisture and heat balance on the plateau and the amount of summer precipitation in most regions of China. A simple frozen soil parameterization scheme was developed to simulate the interaction between permafrost and climate change. This model, combined with the NCAR Community Climate Model 3.6, is suitable for the simulation of permafrost changes on the plateau. In addition, permafrost degradation is one of the main causes responsible for a dropping groundwater table at the source areas of the Yangtze River and Yellow River, which in turn results in lowering lake water levels, drying swamps and shrinking grasslands.

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The evidence for shrub expansion in Northern Alaska and the Pan‐Arctic

2006-03-24

Ken D. Tape , Matthew Sturm , Charles H. Racine

Abstract One expected response to climate warming in the Arctic is an increase in the abundance and extent of shrubs in tundra areas. Repeat photography shows that there has been … Abstract One expected response to climate warming in the Arctic is an increase in the abundance and extent of shrubs in tundra areas. Repeat photography shows that there has been an increase in shrub cover over the past 50 years in northern Alaska. Using 202 pairs of old and new oblique aerial photographs, we have found that across this region spanning 620 km east to west and 350 km north to south, alder, willow, and dwarf birch have been increasing, with the change most easily detected on hill slopes and valley bottoms. Plot and remote sensing studies from the same region using the normalized difference vegetation index are consistent with the photographic results and indicate that the smaller shrubs between valleys are also increasing. In Canada, Scandinavia, and parts of Russia, there is both plot and remote sensing evidence for shrub expansion. Combined with the Alaskan results, the evidence suggests that a pan‐Arctic vegetation transition is underway. If continued, this transition will alter the fundamental architecture and function of this ecosystem with important ramifications for the climate, the biota, and humans.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time

2011-12-05

Sarah C. Elmendorf , Gregory H. R. Henry , Robert D. Hollister +7 more

Ecology Letters (2011) Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate … Ecology Letters (2011) Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site‐specificity of results and uncertainty about the power of short‐term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long‐term warming on tundra vegetation – and associated ecosystem consequences – have the potential to be much greater than we have observed to date.

The impact of new land surface physics on the GCM simulation of climate and climate sensitivity

1999-03-05

Peter M. Cox , Richard Betts , C. B. Bunton +3 more

Role of Land-Surface Changes in Arctic Summer Warming

2005-09-23

F. Stuart Chapin , Matthew Sturm , Mark C. Serreze +7 more

A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in … A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in summer albedo contribute substantially to recent high-latitude warming trends. Pronounced terrestrial summer warming in arctic Alaska correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by about 3 watts per square meter per decade (similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2). The continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating by two to seven times.

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Surface Energy Budgets of Arctic Tundra During Growing Season

2000-01-01

Mark C. Serreze , John E. Walsh , F. Stuart Chapin +7 more

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The impacts of climate change and human activities on biogeochemical cycles on the <scp>Q</scp>inghai‐<scp>T</scp>ibetan <scp>P</scp>lateau

2013-06-06

Huai Chen , Qiuan Zhu , Changhui Peng +7 more

Abstract With a pace of about twice the observed rate of global warming, the temperature on the Qinghai‐Tibetan Plateau (Earth's ‘third pole’) has increased by 0.2 °C per decade over … Abstract With a pace of about twice the observed rate of global warming, the temperature on the Qinghai‐Tibetan Plateau (Earth's ‘third pole’) has increased by 0.2 °C per decade over the past 50 years, which results in significant permafrost thawing and glacier retreat. Our review suggested that warming enhanced net primary production and soil respiration, decreased methane ( CH 4 ) emissions from wetlands and increased CH 4 consumption of meadows, but might increase CH 4 emissions from lakes. Warming‐induced permafrost thawing and glaciers melting would also result in substantial emission of old carbon dioxide ( CO 2 ) and CH 4 . Nitrous oxide ( N 2 O ) emission was not stimulated by warming itself, but might be slightly enhanced by wetting. However, there are many uncertainties in such biogeochemical cycles under climate change. Human activities (e.g. grazing, land cover changes) further modified the biogeochemical cycles and amplified such uncertainties on the plateau. If the projected warming and wetting continues, the future biogeochemical cycles will be more complicated. So facing research in this field is an ongoing challenge of integrating field observations with process‐based ecosystem models to predict the impacts of future climate change and human activities at various temporal and spatial scales. To reduce the uncertainties and to improve the precision of the predictions of the impacts of climate change and human activities on biogeochemical cycles, efforts should focus on conducting more field observation studies, integrating data within improved models, and developing new knowledge about coupling among carbon, nitrogen, and phosphorus biogeochemical cycles as well as about the role of microbes in these cycles.

Influence of the seasonal snow cover on the ground thermal regime: An overview

2005-12-01

Tingjun Zhang

The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high … The presence of seasonal snow cover during the cold season of the annual air temperature cycle has significant influence on the ground thermal regime in cold regions. Snow has high albedo and emissivity that cool the snow surface, high absorptivity that tends to warm the snow surface, low thermal conductivity so that a snow layer acts as an insulator, and high latent heat due to snowmelt that is a heat sink. The overall impact of snow cover on the ground thermal regime depends on the timing, duration, accumulation, and melting processes of seasonal snow cover; density, structure, and thickness of seasonal snow cover; and interactions of snow cover with micrometeorological conditions, local microrelief, vegetation, and the geographical locations. Over different timescales either the cooling or warming impact of seasonal snow cover may dominate. In the continuous permafrost regions, impact of seasonal snow cover can result in an increase of the mean annual ground and permafrost surface temperature by several degrees, whereas in discontinuous and sporadic permafrost regions the absence of seasonal snow cover may be a key factor for permafrost development. In seasonally frozen ground regions, snow cover can substantially reduce the seasonal freezing depth. However, the influence of seasonal snow cover on seasonally frozen ground has received relatively little attention, and further study is needed. Ground surface temperatures, reconstructed from deep borehole temperature gradients, have increased by up to 4°C in the past centuries and have been widely used as evidence of paleoclimate change. However, changes in air temperature alone cannot account for the changes in ground temperatures. Changes in seasonal snow conditions might have significantly contributed to the ground surface temperature increase. The influence of seasonal snow cover on soil temperature, soil freezing and thawing processes, and permafrost has considerable impact on carbon exchange between the atmosphere and the ground and on the hydrological cycle in cold regions/cold seasons.

Vulnerability of Permafrost Carbon to Climate Change: Implications for the Global Carbon Cycle

2008-09-01

Edward A. G. Schuur , James G. Bockheim , Josep G. Canadell +7 more

Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing … Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. In this article we present an overview of the global permafrost C pool and of the processes that might transfer this C into the atmosphere, as well as the associated ecosystem changes that occur with thawing. We show that accounting for C stored deep in the permafrost more than doubles previous high-latitude inventory estimates, with this new estimate equivalent to twice the atmospheric C pool. The thawing of permafrost with warming occurs both gradually and catastrophically, exposing organic C to microbial decomposition. Other aspects of ecosystem dynamics can be altered by climate change along with thawing permafrost, such as growing season length, plant growth rates and species composition, and ecosystem energy exchange. However, these processes do not appear to be able to compensate for C release from thawing permafrost, making it likely that the net effect of widespread permafrost thawing will be a positive feedback to a warming climate.

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Ecological Dynamics Across the Arctic Associated with Recent Climate Change

2009-09-10

Eric Post , Mads C. Forchhammer , M. Syndonia Bret‐Harte +7 more

Assessing the Arctic The Arctic is experiencing some of the most rapid climate change currently under way across the globe, but consequent ecological responses have not been widely reported. At … Assessing the Arctic The Arctic is experiencing some of the most rapid climate change currently under way across the globe, but consequent ecological responses have not been widely reported. At the close of the Fourth International Polar Year, Post et al. (p. 1355 ) review observations on ecological impacts in this sensitive region. The widespread changes occurring in terrestrial, freshwater, and marine systems, presage changes at lower latitudes that will affect natural resources, food production, and future climate buffering.

Plant community responses to experimental warming across the tundra biome

2006-01-20

Marilyn D. Walker , C.-H. Wahren , Robert D. Hollister +7 more

Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to … Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3°C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.

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The Circumpolar Arctic vegetation map

2005-02-24

Donald A. Walker , Martha K. Raynolds , Fred J.A. Daniëls +7 more

Abstract. Question: What are the major vegetation units in the Arctic, what is their composition, and how are they distributed among major bioclimate subzones and countries? Location: The Arctic tundra … Abstract. Question: What are the major vegetation units in the Arctic, what is their composition, and how are they distributed among major bioclimate subzones and countries? Location: The Arctic tundra region, north of the tree line. Methods: A photo‐interpretive approach was used to delineate the vegetation onto an Advanced Very High Resolution Radiometer (AVHRR) base image. Mapping experts within nine Arctic regions prepared draft maps using geographic information technology (ArcInfo) of their portion of the Arctic, and these were later synthesized to make the final map. Area analysis of the map was done according to bioclimate subzones, and country. The integrated mapping procedures resulted in other maps of vegetation, topography, soils, landscapes, lake cover, substrate pH, and above‐ground biomass. Results: The final map was published at 1:7 500 000 scale map. Within the Arctic (total area = 7.11 × 106 km 2 ), about 5.05 × 10 6 km 2 is vegetated. The remainder is ice covered. The map legend generally portrays the zonal vegetation within each map polygon. About 26% of the vegetated area is erect shrublands, 18% peaty graminoid tundras, 13% mountain complexes, 12% barrens, 11% mineral graminoid tundras, 11% prostrate‐shrub tundras, and 7% wetlands. Canada has by far the most terrain in the High Arctic mostly associated with abundant barren types and prostrate dwarf‐shrub tundra, whereas Russia has the largest area in the Low Arctic, predominantly low‐shrub tundra. Conclusions: The CAVM is the first vegetation map of an entire global biome at a comparable resolution. The consistent treatment of the vegetation across the circumpolar Arctic, abundant ancillary material, and digital database should promote the application to numerous land‐use, and climate‐change applications and will make updating the map relatively easy.

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Hydrologic Impacts of Thawing Permafrost—A Review

2016-06-01

Michelle A. Walvoord , Barret L. Kurylyk

Core Ideas This review synthesizes the state of the science in permafrost hydrology. Observed and projected hydrologic impacts of permafrost thaw are discussed. Characterization, modeling, and knowledge gaps of permafrost … Core Ideas This review synthesizes the state of the science in permafrost hydrology. Observed and projected hydrologic impacts of permafrost thaw are discussed. Characterization, modeling, and knowledge gaps of permafrost systems are identified. Translating results between multiple scales in cold regions presents a challenge. Opportunities for advancement in the field of permafrost hydrology are described. Where present, permafrost exerts a primary control on water fluxes, flowpaths, and distribution. Climate warming and related drivers of soil thermal change are expected to modify the distribution of permafrost, leading to changing hydrologic conditions, including alterations in soil moisture, connectivity of inland waters, streamflow seasonality, and the partitioning of water stored above and below ground. The field of permafrost hydrology is undergoing rapid advancement with respect to multiscale observations, subsurface characterization, modeling, and integration with other disciplines. However, gaining predictive capability of the many interrelated consequences of climate change is a persistent challenge due to several factors. Observations of hydrologic change have been causally linked to permafrost thaw, but applications of process‐based models needed to support and enhance the transferability of empirical linkages have often been restricted to generalized representations. Limitations stem from inadequate baseline permafrost and unfrozen hydrogeologic characterization, lack of historical data, and simplifications in structure and process representation needed to counter the high computational demands of cryohydrogeologic simulations. Further, due in part to the large degree of subsurface heterogeneity of permafrost landscapes and the nonuniformity in thaw patterns and rates, associations between various modes of permafrost thaw and hydrologic change are not readily scalable; even trajectories of change can differ. This review highlights promising advances in characterization and modeling of permafrost regions and presents ongoing research challenges toward projecting hydrologic and ecologic consequences of permafrost thaw at time and spatial scales that are useful to managers and researchers.

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Quantifying global soil carbon losses in response to warming

2016-11-29

Thomas W. Crowther , Katherine EO Todd-Brown , C. W. Rowe +7 more

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Permafrost is warming at a global scale

2019-01-10

Boris K. Biskaborn , Sharon L. Smith , Jeannette Noetzli +7 more

Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature … Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across permafrost regions for the period since the International Polar Year (2007-2009). During the reference decade between 2007 and 2016, ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 ± 0.15 °C. Over the same period, discontinuous permafrost warmed by 0.20 ± 0.10 °C. Permafrost in mountains warmed by 0.19 ± 0.05 °C and in Antarctica by 0.37 ± 0.10 °C. Globally, permafrost temperature increased by 0.29 ± 0.12 °C. The observed trend follows the Arctic amplification of air temperature increase in the Northern Hemisphere. In the discontinuous zone, however, ground warming occurred due to increased snow thickness while air temperature remained statistically unchanged.

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Key indicators of Arctic climate change: 1971–2017

2019-04-08

Jason E. Box , William Colgan , Torben R. Christensen +7 more

Key observational indicators of climate change in the Arctic, most spanning a 47 year period (1971–2017) demonstrate fundamental changes among nine key elements of the Arctic system. We find that, … Key observational indicators of climate change in the Arctic, most spanning a 47 year period (1971–2017) demonstrate fundamental changes among nine key elements of the Arctic system. We find that, coherent with increasing air temperature, there is an intensification of the hydrological cycle, evident from increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage. Downward trends continue in sea ice thickness (and extent) and spring snow cover extent and duration, while near-surface permafrost continues to warm. Several of the climate indicators exhibit a significant statistical correlation with air temperature or precipitation, reinforcing the notion that increasing air temperatures and precipitation are drivers of major changes in various components of the Arctic system. To progress beyond a presentation of the Arctic physical climate changes, we find a correspondence between air temperature and biophysical indicators such as tundra biomass and identify numerous biophysical disruptions with cascading effects throughout the trophic levels. These include: increased delivery of organic matter and nutrients to Arctic near‐coastal zones; condensed flowering and pollination plant species periods; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased ignition of wildfires; increased growing season CO2 uptake, with counterbalancing increases in shoulder season and winter CO2 emissions; increased carbon cycling, regulated by local hydrology and permafrost thaw; conversion between terrestrial and aquatic ecosystems; and shifting animal distribution and demographics. The Arctic biophysical system is now clearly trending away from its 20th Century state and into an unprecedented state, with implications not only within but beyond the Arctic. The indicator time series of this study are freely downloadable at AMAP.no.

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Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale

2019-04-25

Jaroslav Obu , Sebastian Westermann , Annett Bartsch +7 more

Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost … Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016 period, driven by remotely-sensed land surface temperatures, down-scaled ERA-Interim climate reanalysis data, tundra wetness classes and landcover map from the ESA Landcover Climate Change Initiative (CCI) project. Subgrid variability of ground temperatures due to snow and landcover variability is represented in the model using subpixel statistics. The results are validated against borehole measurements and reviewed regionally. The accuracy of the modelled mean annual ground temperature (MAGT) at the top of the permafrost is ±2 °C when compared to permafrost borehole data. The modelled permafrost area (MAGT <0 °C) covers 13.9 × 106 km2 (ca. 15% of the exposed land area), which is within the range or slightly below the average of previous estimates. The sum of all pixels having isolated patches, sporadic, discontinuous or continuous permafrost (permafrost probability >0) is around 21 × 106 km2 (22% of exposed land area), which is approximately 2 × 106 km2 less than estimated previously. Detailed comparisons at a regional scale show that the model performs well in sparsely vegetated tundra regions and mountains, but is less accurate in densely vegetated boreal spruce and larch forests.

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Carbon release through abrupt permafrost thaw

2020-02-01

M. R. Turetsky , Benjamin W. Abbott , Miriam C. Jones +7 more

Distinct changes in carbon, nitrogen, and phosphorus cycling in the litter layer across two contrasting forest–tundra ecotones

2025-06-25

Frank Hagedorn , Josephine Imboden , Pavel Moiseev +6 more | Biogeosciences

Abstract. At treeline, plant life forms and species change abruptly from low-stature plants in the tundra to trees in forests. Our study assesses how the vegetation shift affects the quality … Abstract. At treeline, plant life forms and species change abruptly from low-stature plants in the tundra to trees in forests. Our study assesses how the vegetation shift affects the quality and elemental composition of the litter layer and consequently the microbial processing and nutrient release during decomposition. We sampled litter layers along elevation gradients across conifer- and broadleaf-dominated treelines in the Russian subarctic Khibiny Mountains and hemiboreal South Urals. Using microlysimeters at 5 and 15 °C, we measured carbon (C) mineralization and the release of inorganic nitrogen (N) and phosphorus (P), reflecting net N and P mineralization. Additionally, we quantified releases of dissolved organic C and N and analysed the stoichiometry and ecophysiology of microbial biomass. Our findings showed significant shifts in the chemical characteristics of the litter layer across both treeline ecotones. On average, C:N and C:P ratios decreased by 56 % and 65 %, while lignin contents increased by 110 % from tundra to forest. The consistent decrease in C:N:P ratios in the litter layer was paralleled by pronounced increases in net N and P mineralization from tundra to lower-elevation forest in both treeline ecotones. The negligible nutrient release from tundra litter was likely due to immobilization of mineralized N and P at molar C:N and C:P ratios exceeding 35 and 1100, respectively. In contrast to net nutrient mineralization, C mineralization and the release of dissolved organic C and N remained largely unchanged. Microbial biomass colonizing the litter layer showed average decreases of C:N and C:P ratios by 26 % and 74 % from tundra to forest, while potential activities of C–N–P-acquiring extracellular enzymes showed no consistent pattern. Mineralization of 13C-labelled glucose-6-phosphate decreased with decreasing C:N:P ratios from tundra to forest. As the 13C incorporation into microbial biomass remained unaffected, substrate-use efficiency (SUE) increased along the same trajectory. Overall, our results give evidence that the vegetation shift from tundra to forest is associated with an abrupt increase in net N and P mineralization in the litter layer, accelerating nutrient cycling and increasing N and P availability. In contrast, experimental warming by 10 °C was less important for net N and P mineralization than litter composition. This indicates that indirect effects of climatic warming through changes in plant community composition with treeline advances seem to be more important for soil N and P cycling than direct temperature effects.

Numerical Research on Mitigating Soil Frost Heave Around Gas Pipelines by Utilizing Heat Pipes to Transfer Shallow Geothermal Energy

2025-06-24

Peng Xu , Y BAI | Energies

Frost heave in seasonally frozen soil surrounding natural gas pipelines (NGPs) can cause severe damage to adjacent infrastructure, including road surfaces and buildings. Based on the stratigraphic characteristics of seasonal … Frost heave in seasonally frozen soil surrounding natural gas pipelines (NGPs) can cause severe damage to adjacent infrastructure, including road surfaces and buildings. Based on the stratigraphic characteristics of seasonal frozen soil in Beijing, a soil–natural gas pipeline–heat pipe heat transfer model was developed to investigate the mitigation effect of the soil-freezing phenomenon by transferring shallow geothermal energy utilizing heat pipes. Results reveal that heat pipe configurations (distance, inclination angle, etc.) significantly affect soil temperature distribution and the soil frost heave mitigation effect. When the distance between the heat pipe wall and the NGP wall reaches 200 mm, or when the inclined angle between the heat pipe axis and the model centerline is 15°, the soil temperature above the NGP increases by 9.7 K and 17.7 K, respectively, demonstrating effective mitigation of the soil frost heave problem. In the range of 2500–40,000 W/(m·K), the thermal conductivity of heat pipes substantially impacts heat transfer efficiency, but the efficiency improvement plateaus beyond 20,000 W/(m·K). Furthermore, adding fins to the heat pipe condensation sections elevates local soil temperature peaks above the NGP to 274.2 K, which is 5.5 K higher than that without fins, indicating enhanced heat transfer performance. These findings show that utilizing heat pipes to transfer shallow geothermal energy can significantly raise soil temperatures above the NGP and effectively mitigate the soil frost heave problem, providing theoretical support for the practical applications of heat pipes in soil frost heave management.

Bending Stress and Deformation Characteristics of Gas Pipelines in Mountainous Terrain Under the Influence of Subsidence

2025-06-24

Guozhen Zhao , Jiadong Li , Hengchang Liang | Energies

Aiming at the problem that the surface subsidence caused by coal mining in mountainous areas will pose a potential threat to the safe operation of gas pipelines in goaf subsidence … Aiming at the problem that the surface subsidence caused by coal mining in mountainous areas will pose a potential threat to the safe operation of gas pipelines in goaf subsidence areas, taking the geological conditions of Mugua Coal Mine in Shanxi Province as the research background, through the combination of similar simulation and finite element simulation, the deformation and stress characteristics of gas pipelines affected by subsidence in mountainous terrain are analyzed, and the failure law of gas pipelines in different terrains of the coal mining area is revealed. The results demonstrate that topographic stress convergence creates a maximum compression zone at the valley base of the central subsidence basin, causing significant pipeline depression. Hillslope areas primarily experience tension from soil slippage, while slope–valley transition zones exhibit a high-risk shear–tension coupling. Analysis via the pipe–soil interaction model reveals concentrated mid-subsidence pipeline stresses with subsequent relaxation through redistribution. Accordingly, the following zoned protection strategy is proposed: enhanced compression monitoring in valley segments, tensile reinforcement for slope sections, and prioritized shear prevention in transition zones. The research provides a theoretical basis for the safe operation and maintenance of gas pipeline networks in mountainous areas.

Uneven future greening across the northern high latitudes: Regional responses to rising CO2

2025-06-24

Katherine Power | Ecological Modelling

Utilizing Machine Learning Algorithms and Regression Techniques to Develop Pavement Performance Indices for Dry Freeze Climate Regions

2025-06-24

Abdualmtalab Abdualaziz Ali , Abdalrhman Milad , Abdulnaser M. Al-Sabaeei +2 more | Iranian Journal of Science and Technology Transactions of Civil Engineering

Microstructural Investigation of the Effect of Freeze-Thaw Cycles on Engineering Characteristics of Southern Iran Marl Soil

2025-06-24

Mohammad Amiri , S Shahriari , Fatemeh Porhonar | International Journal of Geosynthetics and Ground Engineering

Observations of methane net sinks in the upland Arctic tundra

2025-06-23

Antonio Donateo , Daniela Famulari , Donato Giovannelli +4 more | Biogeosciences

Abstract. This study focuses on direct measurements of CO2 and CH4 turbulent eddy covariance fluxes in tundra ecosystems on the Svalbard islands over a 2-year period. Our results reveal dynamic … Abstract. This study focuses on direct measurements of CO2 and CH4 turbulent eddy covariance fluxes in tundra ecosystems on the Svalbard islands over a 2-year period. Our results reveal dynamic interactions between climatic conditions and ecosystem activities such as photosynthesis and microbial activity. During summer, pronounced carbon uptake fluxes indicate increased photosynthesis and microbial methane consumption, while during the freezing seasons very little exchange was recorded, signifying reduced activity. The observed net summertime methane uptake is correlated with the activation and aeration of soil microorganisms, and it declines in winter due to the presence of snow cover and because of the negative soil temperature which triggers the freezing process of the active layer water content but then rebounds during the melting period. The CH4 fluxes are not significantly correlated with soil and air temperature but are instead associated with wind velocity, which plays a role in the speed of soil drying. Non-growing-season emissions accounted for about 58 % of the annual CH4 budget, characterized by large pulse emissions. The analysis of the impact of thermal anomalies on CO2 and CH4 exchange fluxes underscores that high positive (>5 °C) thermal anomalies may contribute to an increased positive flux in both summer and winter periods, effectively reducing the net annual uptake. These findings contribute valuable insights to our understanding of the dynamics of greenhouse gases in tundra ecosystems in the face of evolving climatic conditions. Further research is required to constrain the sources and sinks of greenhouse gases in dry upland tundra ecosystems in order to develop an effective reference for models in response to climate change.

Permafrost-Affected Gleyzems of the Subpolar Urals: Morphology, Cryogenic Structure, Temperature Regime, and Physicochemical Properties

2025-06-23

Е. В. Жангуров , Dmitry Kaverin , А. А. Дымов +1 more | Eurasian Soil Science

Analysis of formation environments and prediction features of freezing rain and glaze in the Moscow region

2025-06-23

T.G. Dmitrieva , Е.V. Vasil’ev | Hydrometeorological research and forecasting

Formation environments of freezing rain and glaze, methods for their forecasting are considered. The analysis of the cases of these phenomena observed in the Moscow region in the cold seasons … Formation environments of freezing rain and glaze, methods for their forecasting are considered. The analysis of the cases of these phenomena observed in the Moscow region in the cold seasons of 2023‒2024 is performed. Approaches to operational forecasting of the events using the available modern set of information, in particular, the results of the high-resolution ICON-Ru, COSMO-Ru2.2, and COSMO-Ru6 numerical weather prediction models are analyzed. Recommendations for operational forecasters and an algorithm for forecasting freezing rain and glaze for a period up to 3 days are proposed by the example of the Moscow region.

Уникальные асимметричные каменные глетчеры Куртатинского ущелья Республики Северная Осетия-Алания

2025-06-22

Р.А. Тавасиев | Вестник Владикавказского научного центра

В статье изложены результаты исследования уникальных асимметричных каменных глетчеров бассейна реки Фиагдон в верховьях Куртатинского ущелья. The article sets out the results of a study of unique asymmetric stone glaciers … В статье изложены результаты исследования уникальных асимметричных каменных глетчеров бассейна реки Фиагдон в верховьях Куртатинского ущелья. The article sets out the results of a study of unique asymmetric stone glaciers of the Fiagdon River basin in the upper reaches of the Kurtatinsky Gorge.

Comparative analysis of soil thermal conductivity in the permafrost regions of the Qinghai–Tibetan Plateau and the Arctic

2025-06-21

Wenhao Liu , Li Ren , Xiaofan Zhu +7 more | Geoderma

Organic carbon, mercury, and sediment characteristics along a land–shore transect in Arctic Alaska

2025-06-20

Frieda P. Giest , Maren Jenrich , Guido Grosse +4 more | Biogeosciences

Abstract. Climate warming in the Arctic results in thawing permafrost and associated processes like thermokarst, especially in ice-rich permafrost regions. Since permafrost soils are one of the largest organic carbon … Abstract. Climate warming in the Arctic results in thawing permafrost and associated processes like thermokarst, especially in ice-rich permafrost regions. Since permafrost soils are one of the largest organic carbon reservoirs of the world, their thawing leads to the release of greenhouse gases due to increasing microbial activity with rising soil temperature, further exacerbating climate warming. To enhance the predictions of potential future impacts of permafrost thaw, a detailed assessment of changes in soil characteristics in response to thermokarst processes in permafrost landscapes is needed, which we investigated in this study in an Arctic coastal lowland. We analysed six sediment cores from the Arctic Coastal Plain of northern Alaska, each representing a different landscape feature along a gradient from upland to thermokarst lake and drained basin to thermokarst lagoon in various development stages. For the analysis, a multiproxy approach was used, including sedimentological (grain size, bulk density, ice content), biogeochemical (total organic carbon (TOC), TOC density (TOCvol), total nitrogen (TN), stable carbon isotopes (δ13C), TOC/TN ratio, mercury (Hg)), and lipid biomarker (n-alkanes, n-alkanols, and their ratios) parameters. We found that a semi-drained state of thermokarst lakes features the lowest OC content, and TOC and TN are generally higher in unfrozen deposits, hinting at a more intact state of organic matter. Indicated by the average chain length (ACL), δ13C, Paq, and Pwax, we found a stronger influence of aquatic organic matter (OM) in the OM composition in the soils covered by water compared to those not covered by water. Moreover, the results of the δ13C, TOC/TN ratio, and CPI indicate that the saline deposits contain stronger degraded OM than the deposits not influenced by saltwater. Additionally, we found positive correlations between the TOC and TOCvol and the Hg content in the deposits. The results indicate that thermokarst-influenced deposits tend to accumulate Hg during thawed periods and thus contain more Hg than the upland permafrost deposits that have not been impacted by lake formation. Our findings offer valuable insights into the dynamics of carbon storage and vulnerability to decomposition in coastal permafrost landscapes, reflecting the interplay of environmental factors, landform characteristics, and climate change impacts on Arctic permafrost environments.

The thermal conductivity characteristics and prediction models of limestone sand-yellow soil mixtures

2025-06-20

Xiong Liu , Ruiyong Mao , Zujing Zhang +3 more | Case Studies in Thermal Engineering

Influences of the China–Russia Crude Oil Pipelines on the Characteristics of Soil Bacterial and Fungal Communities in Permafrost Regions of the Da Xing’anling Mountains, Northeast China

2025-06-20

Xue Yang , Yanling Shi , Xiaoying Jin +4 more | Forests

Engineering disturbances are increasing in permafrost regions of northeastern China, where soil microorganisms play essential roles in biogeochemical cycling and are highly sensitive to linear infrastructure disturbances. However, limited research … Engineering disturbances are increasing in permafrost regions of northeastern China, where soil microorganisms play essential roles in biogeochemical cycling and are highly sensitive to linear infrastructure disturbances. However, limited research has addressed how microbial communities respond to different post-engineering-disturbance recovery stages. This study investigated the impacts of the China–Russia Crude Oil Pipelines (CRCOPs) on soil microbial communities in a typical boreal forest permafrost zone of the Da Xing’anling Mountains. Soil samples were collected from undisturbed forest (the control, CK); short-term disturbed sites associated with Pipeline II, which was constructed in 2018 (SD); and long-term disturbed sites associated with Pipeline I, which was constructed in 2011 (LD). Pipeline engineering disturbances significantly increased soil clay content and pH while reducing soil water content (SWC), soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) (p < 0.05). No significant differences in these soil properties were observed between SD and LD. Bacterial diversity increased significantly, whereas fungal diversity significantly decreased following pipeline disturbances (p < 0.05). The beta diversity of both bacterial and fungal communities differed significantly among the three disturbance types. At the phylum level, pipeline disturbance increased the relative abundances of Proteobacteria, Acidobacteriota, Actinobacteriota, Ascomycota, and Mortierellomycota while reducing those of Bacteroidota and Basidiomycota. These shifts were associated with disturbance-induced changes in soil properties. Microbial co-occurrence networks in SD exhibited greater complexity and connectivity than those in CK and LD, suggesting intensified biotic interactions and active ecological reassembly during the early recovery phase. These findings suggest that pipeline disturbance could drive soil microbial systems into a new stable state that is difficult to restore over the long term, highlighting the profound impacts of linear infrastructure on microbial ecological functions in cold regions. This study provides a scientific basis for ecological restoration and biodiversity conservation in permafrost-affected areas.

Multiscale Deterioration of Physical and Triaxial Mechanical Behaviors of Fine-Grained Sandstone Under Cyclic Freezing–Thawing: Experimental Observation and Microstructural Interpretation

2025-06-20

Kesheng Li , Long-Xiao Chen , Sheng‐Qi Yang +2 more | Rock Mechanics and Rock Engineering

Improving regional soil water-salt management by modeling soil freezing-thawing processes in a cold-arid irrigation district, upper Yellow River basin

2025-06-20

Lvyang Xiong , Yao Jiang , Junyu Qi +1 more | Journal of Hydrology Regional Studies

Modeling active layer thickness in permafrost rock walls based on an analytical solution of the heat transport equation, Kitzsteinhorn, Hohe Tauern Range, Austria

2025-06-20

Wolfgang Aumer , Ingo Hartmeyer , Carolyn‐Monika Görres +3 more | Earth Surface Dynamics

Abstract. The active layer thickness (ALT) refers to the seasonal thaw depth of a permafrost body and in high alpine environments represents an essential parameter for natural hazard analysis. The … Abstract. The active layer thickness (ALT) refers to the seasonal thaw depth of a permafrost body and in high alpine environments represents an essential parameter for natural hazard analysis. The aim of this study is to model ALT based on bedrock temperature data measured in four shallow boreholes (SBs, 0.1 m deep) in the summit region of the Kitzsteinhorn (Hohe Tauern Range, Austria, Europe). We set up our heat flow model with temperature data (2016–2021) from a 30 m deep borehole (DB) drilled into bedrock at the Kitzsteinhorn north face. For modeling purposes, we assume one-dimensional conductive heat flow and present an analytical solution of the heat transport equation through sinusoidal temperature waves resulting from seasonal temperature oscillations (damping depth method). The model approach is considered successful: in the validation period (2019–2021), modeled and measured ALT differed by only 0.1 ± 0.1 m, with a root mean square error (RMSE) of 0.13 m. We then applied the DB-calibrated model to four SBs and found that the modeled seasonal ALT maximum ranged between 2.5 m (SB 2) and 10.6 m (SB 1) in the observation period (2013–2021). Due to small differences in altitude (∼200 m) within the study area, slope aspect had the strongest impact on ALT. To project future ALT deepening due to global warming, we integrated IPCC climate scenarios SSP1-2.6 and SSP5-8.5 into our model. By mid-century (∼2050), ALT is expected to increase by 48 % at SB 2 and by 62 % at DB under scenario SSP1-2.6 (56 % and 128 % under scenario SSP5-8.5), while permafrost will no longer be present at SB 1, SB 3, and SB 4. By the end of the century (∼2100), permafrost will only remain under scenario SSP1-2.6 with an ALT increase of 51 % at SB 2 and of 69 % at DB.

A theoretical thermal conductivity model for petroleum hydrocarbons-contaminated soils under unfrozen and frozen states

2025-06-19

Jun Bi , Mengyun Mao , Wenxuan Mu +4 more | International Communications in Heat and Mass Transfer

Effect of freeze–thaw and chemical washing on heavy metal removal based on three-dimensional soil pore model characterization

2025-06-18

Lulu Wu , Jialong Lv | Water Air & Soil Pollution

Unloading strength and damage properties of deep frozen clay subjected to long-term high-pressure K0 consolidation

2025-06-18

Jinbo Jia , Xingyu Zhang , Peixin Sun +1 more | Geomechanics and Geophysics for Geo-Energy and Geo-Resources

Thermo-hydro-mechanics of thawing permafrost: a phase-field framework with enriched modified Cam-Clay plasticity

2025-06-17

Mahyar Malekzade Kebria , SeonHong Na , Susan Tighe | Acta Geotechnica

Next-generation hybrid precipitation forecasts that integrate Indigenous knowledge

2025-06-16

Samuel Jonson Sutanto , Joep Jonson Bosdijk , Imme Benedict +4 more | Environmental Research Letters

Abstract Many smallholder farmers in the Global South utilize local forecasts based on Indigenous knowledge due to limited reliability and accessibility of scientific weather forecasts. The use of local forecast, … Abstract Many smallholder farmers in the Global South utilize local forecasts based on Indigenous knowledge due to limited reliability and accessibility of scientific weather forecasts. The use of local forecast, however, faces challenges by increasing climate variability, which undermines farmers’ confidence in their forecast. This study addresses these challenges by developing a hybrid forecast that integrates both scientific and local forecast using machine learning techniques to improve precipitation predictions in northern Ghana. Results show that the hybrid forecast improves precipitation forecast accuracy by 23% and 33% compared to scientific forecast and local forecast, respectively. The best performance is achieved by combining two random forests or a voting classifier and a random forest. This research highlights the potential of machine learning to develop more accurate hybrid forecast than other statistical methods. Such enhanced precipitation forecasts could enable smallholder farmers in the Global South to make better-informed agricultural decisions, ultimately enhancing their livelihoods.

Mapping global distributions, environmental controls, and uncertainties of apparent topsoil and subsoil organic carbon turnover times

2025-06-16

Lei Zhang , Lin Yang , Thomas W. Crowther +7 more | Earth system science data

Abstract. The turnover time (τ) of global soil organic carbon is central to the functioning of terrestrial ecosystems. Yet our spatially explicit understanding of the depth-dependent variations and environmental controls … Abstract. The turnover time (τ) of global soil organic carbon is central to the functioning of terrestrial ecosystems. Yet our spatially explicit understanding of the depth-dependent variations and environmental controls of τ at a global scale remains incomplete. In this study, we combine multiple state-of-the-art observation-based datasets, including over 90 000 geo-referenced soil profiles, the latest root observations distributed globally, and large numbers of satellite-derived environmental variables, to generate global maps of apparent τ in topsoil (0–0.3 m) and subsoil (0.3–1 m) layers, with a spatial resolution of 30 arcsec (∼1 km at the Equator). We show that subsoil τ (385203485 years (mean, with a variation range from the 2.5th to 97.5th percentile)) is over 8 times longer than topsoil τ (1511137 years). The cross-validation shows that the fitted machine learning models effectively captured the variabilities in τ, with R2 values of 0.87 and 0.70 for topsoil and subsoil τ mapping, respectively. The prediction uncertainties of the τ maps were quantified for better user applications. The environmental controls on topsoil and subsoil τ were investigated at global, biome, and local scales. Our analyses illustrate the ways in which temperature, water availability, physio-chemical properties, and depth jointly exert impacts on τ. The data-driven approaches allow us to identify their interactions, thereby enriching our comprehension of mechanisms driving nonlinear τ–environment relationships at global to local scales. The distributions of dominating factors of τ at local scales were mapped for purposes of identifying context-dependent controls on τ across different regions. We further reveal that the current Earth system models may underestimate τ by comparing model-derived maps with our observation-derived τ maps. The resulting maps, with new insights, as demonstrated in this study, will facilitate future modelling efforts relating to carbon cycle–climate feedbacks and support effective carbon management. The dataset is archived and freely available at https://doi.org/10.5281/zenodo.14560239 (Zhang, 2025a).

Impact dynamic mechanical properties of frozen-soils with different moisture contents following varying numbers of freeze-thaw cycle

2025-06-16

Bin Li , Zhiwu Zhu , Wurong Jia +2 more | International Journal of Damage Mechanics

Frozen-soils with different moisture contents (MCs) often experience freeze-thaw cycles (FTCs) owing to fluctuations in seasonal or day-night temperature. The influence of FTC on the impact dynamic mechanical properties of … Frozen-soils with different moisture contents (MCs) often experience freeze-thaw cycles (FTCs) owing to fluctuations in seasonal or day-night temperature. The influence of FTC on the impact dynamic mechanical properties of frozen-soils with different MCs was investigated in this study. The impact dynamic compression tests on frozen-soils with different MCs (20%, 25%, and 30%) following varying numbers of FTC (0, 1, 3, 5, and 7) using a split Hopkinson pressure bar apparatus were conducted. The experimental results revealed that the impact dynamic strength of the frozen-soil was related to the number of FTC and MC. A threshold exists for the number of FTC for the frozen-soil. Before reaching this threshold, the impact dynamic strength of the frozen-soil progressively decreased with an increasing number of FTC. Further, the threshold decreased as the MC decreased. Analyzing the energy of frozen-soil during impact process, an expression for the FTC damage in frozen-soils with different MCs was established using the energy density. The reinforcing effect of ice particles on the impact dynamic mechanical properties of frozen-soil was examined, and the elastic constants for the frozen-soils with different MCs were evaluated using micromechanical theory. Furthermore, a finite element numerical model of frozen-soil was developed by integrating cohesive elements into solid elements via Python scripting using the cohesive zone model. The impact dynamic mechanical behavior and crack evolution behavior of frozen-soils with different MCs following varying numbers of FTCs were simulated by considering the mechanisms of FTC degradation and ice particles reinforcement. The validity of the model was confirmed by comparing simulation and experimental results.

To Study the Impact of Chloride Compounds on the Characteristics of Clay Soil

2025-06-16

Vikas Gautam | International Journal for Research in Applied Science and Engineering Technology

This study investigates the impact of chloride compounds (CaCl2, MgCl2 and NaCl) on clay soil, aiming to provide valuable insights into the behavior and potential consequences of introducing chloride-based materials … This study investigates the impact of chloride compounds (CaCl2, MgCl2 and NaCl) on clay soil, aiming to provide valuable insights into the behavior and potential consequences of introducing chloride-based materials into clay-rich soil. Clay soils are prevalent in various regions worldwide and are known for their unique properties, including high plasticity and low permeability. Understanding how chloride compounds interact with clay soils is crucial for numerous fields, including geotechnical engineering, environmental science, and agriculture. The research involved laboratory experiments on clay soil samples added with varying concentrations (1%, 3%, and 5%) of chloride compounds (CaCl₂, MgCl₂, NaCl). Tests assessed physical and chemical changes in the soil, including consistency limits, optimum moisture content, maximum dry density, and unconfined compressive strength. Results showed that increasing chloride concentration led to a decrease in liquid limit, plastic limit, plasticity index, and optimum moisture content. Conversely, maximum dry density and unconfined compressive strength increased. Where, CaCl₂ consistently produced the greatest improvement in strength and reduction in plasticity, while NaCl had the mildest effect. These findings are relevant for both soil stabilization practices and understanding the environmental impact of saline intrusion.

Climate change adaptation in the Arctic through sustainable socio-ecological innovation: Creating opportunities for local communities while preserving ecological value

2025-06-15

I Bianco | Deleted Journal

The Arctic is heating at 4 times the rate than any other region in the planet. Climate change has been so rapid that many species and the native communities that … The Arctic is heating at 4 times the rate than any other region in the planet. Climate change has been so rapid that many species and the native communities that depend on them have been severely affected. Climate change adaptation must be a priority for arctic communities and can be supported by initiatives that are beneficial to both local communities and the ecosystems at risk. This paper presents a framework of conservation using sustainable business models that preserve and augment natural capital to create resilience the Arctic. This model can be used also for other regions vulnerable regions to rapid climate change. In this paper we review the actors and solutions that might be most effective on decarbonization and preservation of natural and social capital in the Arctic. Our results show that the oil and gas industry possess the technology, mechanisms and expertise to more effectively transfer capabilities from high carbon intensity to carbon sequestration activities. These mechanisms go beyond conservation, aiding energy and nutrients transfers and integrate ecology, biodiversity and community building through rural renewal and innovative business models.

Understanding the influence of thermal properties and surface conditions on thermal modelling results at two permafrost sites

2025-06-13

Konstantin Ozeritskiy , Jocelyn L. Hayley | Canadian Geotechnical Journal

This study evaluates the thermal behavior of permafrost under varying surface boundary conditions at a specific site on the Yamal Peninsula, focusing on the impact of snow cover depth, wind … This study evaluates the thermal behavior of permafrost under varying surface boundary conditions at a specific site on the Yamal Peninsula, focusing on the impact of snow cover depth, wind speed, and soil thermal properties through one-dimensional thermal modeling. For comparison purposes, a site at the Hudson Bay Lowland with lower snow accumulation was also included to assess the influence of differing snow conditions on thermal dynamics. The analysis highlights the sensitivity of thermal models to surface condition measurements, emphasizing that even small errors in snow cover estimation can significantly affect simulated ground temperatures. While soil thermal properties remain influential, their impact is comparatively less pronounced than variations in snow cover. Results indicate that inaccuracies in snow cover measurements, particularly during atypical winters, can lead to substantial deviations in modeled thermal fields. These findings underscore the importance of refining surface condition measurements to enhance the reliability of thermal modeling in permafrost regions.

Early season precipitation addition offsets warming effect on carbon and water use efficiency in Qinghai-Xizang Plateau

2025-06-13

Ayisha Oyont , Zheng Li , Guozheng Hu +5 more | Ecosystem Health and Sustainability

Machine Learning and Morphometric Analysis for Evaluating the Vulnerability of Tundra Landscapes to Thermokarst Hazards in the Lena Delta: A Case Study of Arga Island

2025-06-13

Andrei Kartoziia | GeoHazards

Analyses of thermokarst hazard risk are becoming increasingly crucial in the context of global warming. A significant aspect of thermokarst research is the mapping of landscapes based on their vulnerability … Analyses of thermokarst hazard risk are becoming increasingly crucial in the context of global warming. A significant aspect of thermokarst research is the mapping of landscapes based on their vulnerability to thermokarst processes. The exponential growth of remote sensing data and the advent of novel techniques have paved the way for the creation of sophisticated techniques for the study of natural disasters, including thermokarst phenomena. This study applies machine learning techniques to assess the vulnerability of tundra landscapes to thermokarst by integrating supervised classification using random forest with morphometric analysis based on the Topography Position Index. We recognized that the thermokarst landscape with the greatest potential for future permafrost thawing occupies 20% of the study region. The thermokarst-affected terrains and water bodies located in the undegraded uplands account for 13% of the total area, while those in depressions and valleys account for 44%. A small part (6%) of the study region represents areas with stable terrains within depressions and valleys that underwent topographic alterations and are likely to maintain stability in the future. This approach enables big geodata-driven predictive modeling of permafrost hazards, improving thermokarst risk assessment. It highlights machine learning and Google Earth Engine’s potential for forecasting landscape transformations in vulnerable Arctic regions.

A novel approach to assess the cumulative impacts of thawing permafrost on aquatic systems using both Indigenous knowledge and western scientific knowledge

2025-06-13

Jackie A. Ziegler , Trevor C. Lantz , Mike Newton +3 more | Canadian Journal of Fisheries and Aquatic Sciences

Increased temperatures and precipitation are intensifying mass wasting caused by the thawing of ice-rich permafrost in the western Canadian Arctic. Specifically, disturbances known as retrogressive thaw slumps deliver large quantities … Increased temperatures and precipitation are intensifying mass wasting caused by the thawing of ice-rich permafrost in the western Canadian Arctic. Specifically, disturbances known as retrogressive thaw slumps deliver large quantities of sediment and dissolved materials into adjacent waterbodies, thereby negatively affecting culturally and ecologically important fish habitat. Very little information exists regarding the impacts of thaw slump expansion on fish habitat in northern Canada. To understand the risk of these potential impacts, we combined spatial data on cumulative thaw slump impacts in the Teetł’it Gwinjik (Peel River) Watershed, Gwich’in Settlement Region, with detailed information about fish habitat derived from Gwich’in knowledge and western scientific knowledge using a mixed methods approach. Areas at high risk of experiencing the cumulative impacts of slumping were found along the mainstem of the Peel River and its major tributaries. Gwich’in knowledge holders were concerned about the impacts of slumping on future access to fish. These findings raise concerns about the impact of permafrost thaw on Indigenous fishing livelihoods in the region and highlights the need for additional research.

Propagation characteristics of thermo-elastic waves in saturated frozen soil

2025-06-13

Jie Xu , Liang Li , Hongyun Jiao +2 more | Computers and Geotechnics

Unconfined compressive strength prediction of lime-stabilised clayey soils under freeze-thaw conditions

2025-06-12

Youssouf Toualbia , Billal Sari-Ahmed , Giulia La Porta +3 more | Environmental Geotechnics

In cold regions, and considering the increasing concerns regarding climate change, it is crucial to assess soil stabilisation techniques under adverse environmental conditions. The study addresses the challenge of forecasting … In cold regions, and considering the increasing concerns regarding climate change, it is crucial to assess soil stabilisation techniques under adverse environmental conditions. The study addresses the challenge of forecasting geotechnical properties of lime-stabilised clayey soils subjected to freeze-thaw conditions. A model is proposed to accurately predict the unconfined compressive strength (UCS) of lime-stabilised clayey soils exposed to freeze-thaw cycles. As the prediction of UCS is essential in construction engineering, the use of the model is a viable early-phase alternative to time-consuming laboratory testing procedures. This research aims to propose a robust predictive model using readily accessible soil parameters. A comprehensive statistical model for predicting UCS was developed and validated using data sourced from the scientific literature. An extensive parametric analysis was conducted to assess the predictive performance of the developed model. The findings underscore the capability of statistical models to predict UCS of stabilised soils demonstrating their valuable contribution to this area of study.

The role of catchment characteristics, discharge, and active- layer thaw in seasonal stream chemistry across 10 permafrost catchments

2025-06-12

Arsh Grewal , Erin M. Nicholls , Sean K. Carey | Hydrology and earth system sciences

Abstract. High-latitude catchments are rapidly warming, leading to altered precipitation regimes, widespread permafrost degradation, and shifts in stream chemistry across major arctic rivers. In headwater catchments, seasonal deepening of flow … Abstract. High-latitude catchments are rapidly warming, leading to altered precipitation regimes, widespread permafrost degradation, and shifts in stream chemistry across major arctic rivers. In headwater catchments, seasonal deepening of flow paths due to active-layer thaw and declining discharge post-snowmelt drive variability in stream chemistry during the open-water period. In North American permafrost regions, activation of deeper mineral layers as the season progresses typically increases major-ion concentrations while decreasing dissolved organic carbon (DOC) concentrations. Despite decades of research on seasonality in stream chemistry within permafrost regions, the relative influence of active-layer thaw and discharge remains unresolved. Additionally, the role of permafrost extent and topography in driving seasonality of these solutes is poorly constrained. To address these knowledge gaps, we measured discharge and sampled major-ion and dissolved organic carbon (DOC) concentrations across 10 permafrost catchments in Yukon Territory, Canada. We analyzed concentration–discharge relationships using generalized additive models to resolve the distinct influence of discharge and seasonal active-layer thaw on stream chemistry and to identify the role of watershed characteristics on the magnitude and seasonality of solute concentrations. After accounting for seasonal variations in discharge, we found that both major ions and DOC were highly seasonal across all catchments, with DOC declining and major-ion concentrations increasing post-freshet. Seasonal variability in major-ion concentrations was primarily driven by active-layer thaw, whereas DOC seasonality was strongly influenced by flushing of soil organic carbon during freshet. While average major-ion concentrations were geologically mediated, greater permafrost extent led to enhanced seasonality in concentrations. Catchments with strong topographical gradients and thinner organic soils had higher specific discharge and lower DOC concentrations but greater relative seasonality. Our results highlight the important role catchment characteristics play in shaping the seasonal variations in and magnitude of solute concentrations in permafrost-underlain watersheds.

Dynamic tensile mechanical properties and damage fracture mechanisms of saturated frozen sandstone

2025-06-12

Ming Li , Fuqiang Zhu , Yiwen Mao +5 more | Geomechanics and Geophysics for Geo-Energy and Geo-Resources

Assessment of the impacts of climate change on cold region pavement design and operation

2025-06-11

Yusheng Jiang , Shafi Ullah , Claudia E. Zapata +1 more | Journal of Infrastructure Preservation and Resilience

Abstract Cold region pavements are subjected to climate impacts, as frost heave and thaw settlement can significantly deteriorate the pavement surface conditions and reduce its service life. Due to the … Abstract Cold region pavements are subjected to climate impacts, as frost heave and thaw settlement can significantly deteriorate the pavement surface conditions and reduce its service life. Due to the freezing/thawing behaviors, the smoothness of the flexible pavement surface usually shows seasonal fluctuations, i.e., an increases or decreases of international roughness index (IRI) during freezing season or thawing season, respectively. However, few existing models capture such season-dependent mode of IRI variations. In this study, calibrated models for flexible pavement are proposed for evaluating the IRI on seasonal scales through both global and local calibrations. The globally calibrated model successfully links the freezing–thawing processes to flexible pavement performance. The performance of both the global and local calibrations are verified by field measurements at selected road sections and Mechanistic Empirical Pavement Design Guide (MEPDG) model predictions. The proposed model connects climatic factors with pavement performance, and therefore offering a tool to assess the pavement IRI response to future climate changes. Based on the globally calibrated model, a series of analyses were conducted to forecast the impacts of climate change on IRI at sites located in different cold climate zones. The effects of climate change on pavement construction and operation are investigated. From this, the impacts of climate change on pavement design adaptation as well as the environmental footprint of vehicle operations are estimated.