Cryospheric Changes Research Articles

The impact of climate change on seasonal glaciation in the mountainous permafrost of North-Eastern Eurasia by the example of the giant Anmangynda aufeis

This study examines the evolving dynamics of spring aufeis fields in the mountain permafrost zone of North-Eastern Eurasia, emphasizing their significance as indicators of permafrost-hydrogeological processes. Focusing on the representative Anmangynda river basin giant aufeis field, our research spans 1962 to 2022 and unveils temporal variations in aufeis characteristics.Over the historical period (1963–1990), the aufeis maximum pre-ablation area ranged from 4.3 to 6.8 km2, with a volume of 5.3 to 11.7 million m3. In the present era (2000–2022), these figures decreased to 3.5–5.4 km2 and 5.0–8.2 million m3, respectively. The region experienced heightened air temperatures and precipitation, with the most significant shifts occurring during early winter (October–December). Increased snow cover depth and earlier formation were also observed. Ground temperatures followed suit with an upward trend. Correlation analyses reveal a noteworthy link between average air temperatures from August to November and aufeis characteristics in both historical and current contexts. Moreover, solid precipitation and air temperatures in November and December displayed a moderate yet statistically significant correlation with aufeis size parameters during 2000–2022. Notably, no significant correlation emerged between aufeis characteristics and the Anmangynda River streamflow or liquid precipitation. This research underscores the interplay between climatic variables and aufeis dynamics, offering insights into the impacts of changing climatic conditions on the permafrost-hydrogeological system. The observed reduction of aufeis area and volume, coupled with the altered freezing and melting periods, align with broader cryospheric changes. As aufeis fields continue to evolve, this study highlights the complexities in their responses and their relevance as indicators of climate-driven alterations in the cryosphere. Further research is essential to fully unravel these intricate relationships and assess their implications for regional hydrology and ecosystems.

Dynamic controls of the interannual and interdecadal variations of the freezing level height over the Tibetan Plateau

The variation of freezing level height (FLH) is significantly indicated the cryosphere change under global warming. In this study, the FLH during boreal summer in the TP regions is investigated, with the leading mode of a mono-sign pattern both on interannual and interdecadal timescales. The interannual variation of the summer FLH is dominantly coupled with the summer Arctic Oscillation (AO). When the AO is in positive phase, positive geopotential height anomalies are prolonged in the mid-latitude and negative anomalies are present over the Arctic regions. Meanwhile, the westerly shifts northward and strengthened, preventing the cold air propagating southward. These conditions are beneficial for the surface and free-air temperature increasing and thus enhance the FLH over the TP. On the interdecadal timescale, the Pacific Decadal Oscillation (PDO) has mainly contributed to the variation of summer FLH. In the negative PDO phase, the warming sea surface temperature anomalies appear in the North Pacific, which could drive wave trains propagating eastward and induce high pressure around the northern TP. With the anomalous anticyclone from TP to western North Pacific, the southeasterly wind is prevalent in the TP. Consequently, the northern TP becomes warming remarkably and leads to the rising of FLH. This study provides an insight perspective for understanding the changes of FLH over the TP, which also suggests the influence on the cryosphere processes at multi-timescale variations.

Editorial: Hydrological and chemical effects of a changing cryosphere on mountain freshwaters

Editorial: Hydrological and chemical effects of a changing cryosphere on mountain freshwaters

Inequalities of ice loss: a framework for addressing sociocryospheric change

AbstractCryospheric change occurs in unequal spaces. Societies living near ice are divided by race, class, gender, geography, politics and other factors. Consequently, impacts of ice loss are not shared equally, and everyone experiences cryospheric changes differently. Responsibility for recent ice loss is also driven by a relatively small portion of humanity: those who emit the most greenhouse gases. Additionally, people who study the cryosphere come from institutions and societies where inequality is often systemic, making research on ice and snow a symptom of and contributor to social inequality. To better understand unequal effects of cryospheric change within and across diverse communities, including research communities, this paper focuses on three areas, drawing primarily from glacier-related work: (1) the social context of cryospheric changes; (2) attribution and responsibility for cryospheric changes and (3) imbalances in knowledge about the cryosphere. Addressing these dimensions of ice loss requires transdisciplinary approaches that connect research to societies and link glaciology and other cryospheric sciences with social sciences and humanities. These concepts, cases and suggestions to help address inequalities also reveal that no singular conceptualization of sustainability exists. Different societies, residents and researchers possess distinct understandings of and goals for ‘ice in a sustainable society’.

Arctic and red fox population responses to climate and cryosphere changes at the Arctic's edge.

Responses of one species to climate change may influence the population dynamics of others, particularly in the Arctic where food webs are strongly linked. Specifically, changes to the cryosphere may limit prey availability for predators. We examined Arctic (Vulpes lagopus) and red fox (V. vulpes) population dynamics near the southern edge of the Arctic fox distribution using fur harvest records from Churchill, Manitoba, Canada between 1955 and 2012. Arctic foxes showed a declining population trend over time (inferred from harvest records corrected for trapping effort), whereas the red fox population trend was relatively stable. The positive relationship between the annual Arctic and red fox harvests suggested interspecific competition did not promote the Arctic fox decline. To investigate alternative mechanisms, we evaluated the relative influence of sea-ice phenology, snow depth, snow duration, winter thaws, and summer temperature on the harvest dynamics of both species in the most recent 32years (1980-2012; n = 29) of our data. Arctic fox harvests were negatively related to the length of time Hudson Bay was free of sea ice. Shorter sea ice duration may reduce access to seal carrion as an alternative winter food source when lemming densities decline. Contrary to our prediction, red fox harvest was not related to summer temperature but was positively related to snow depth, suggesting winter prey availability may limit red fox population growth. Predators have an important ecological role, so understanding the influence of changes in the cryosphere on predator-prey interactions may better illuminate the broader influence of climate change on food-web dynamics.

The global change and response special project: using remote sensing data to monitor and invert key components in the cryosphere

It is critical to understand the mechanisms and impacts of global climate change in cryosphere and polar environment. Here we describe the design and progress of the remote sensing products we have developed to monitor these changes. We obtain datasets by combining multi-sensor remote sensing systems with field validation systems, and then develop a methodological system that combines multiple sources and calibration technologies to address the challenges of data heterogeneity in dynamically monitoring key parameters. This global change and response special project supported by the National Key Research and Development Program of China, named “observation and inversion of critical parameters of changes in the cryosphere and polar environment”, providing comprehensive records of essential elements of the cryosphere through long-term satellite records. The multi-team is completing the project and collecting data from multi-sensor to create remote sensing data products that include records of changes in the cryosphere, such as permafrost, glaciers, ice sheet mass balance, seasonal snow accumulation, sea ice, and albedo changes. Finally, the existing ground- and space-based observing system can be improved to provide dynamic monitoring of key parameters in the cryosphere and changes in the polar environment.

Tracing the impacts of recent rapid sea ice changes and the A68 megaberg on the surface freshwater balance of the Weddell and Scotia Seas.

The Southern Ocean upper-layer freshwater balance exerts a global climatic influence by modulating density stratification and biological productivity, and hence the exchange of heat and carbon between the atmosphere and the ocean interior. It is thus important to understand and quantify the time-varying freshwater inputs, which is challenging from measurements of salinity alone. Here we use seawater oxygen isotopes from samples collected between 2016 and 2021 along a transect spanning the Scotia and northern Weddell Seas to separate the freshwater contributions from sea ice and meteoric sources. The unprecedented retreat of sea ice in 2016 is evidenced as a strong increase in sea ice melt across the northern Weddell Sea, with surface values increasing approximately two percentage points between 2016 and 2018 and column inventories increasing approximately 1 to 2 m. Surface meteoric water concentrations exceeded 4% in early 2021 close to South Georgia due to meltwater from the A68 megaberg; smaller icebergs may influence meteoric water at other times also. Both these inputs highlight the importance of a changing cryosphere for upper-ocean freshening; potential future sea ice retreats and increases in iceberg calving would enhance the impacts of these freshwater sources on the ocean and climate. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

Modeling of land use change under the recent climate projections of CMIP6: a case study of Indian river basin.

The aim of the study was to investigate the land use change dynamics under CMIP6 projections using Land Change Modeler(LCM). The Global Sensitivity Analysis (GSA) techniques was applied to quantify the sensitivity of single parameter and combinationof parameters. Land use and land cover (LULC) transitions of the baseline period (2006-2016) was assessed with a model performance accuracy of 80%. Receiver operating characteristic (ROC) analysis shows that the model has performed well for all the LULC classes except builtup land. Prediction under the SSP245 scenario depicts that areal extent of agricultural, forest, and snow, and glacier will decrease by the mid-century (2045). However, the grassland and barren land areawill increase from the baseline period. A similar change pattern with a higher magnitude has also been predicted under SSP585 scenario. The CMIP6 forcing index considers socio-economic effects and LCMpredicted an expansion in barren land which may be attributed to changes in cryosphere in the studied area.

The cryosphere change will intensify the summer drought in Qilian Mountains, northeastern of the Tibetan plateau

Study regionThis study focuses on the upper reaches of Shule river (URSLH) and Heihe river (URHH) basins and Taolai river (URTLH) basin in Qilian Mountains. Study focusThe impact of the cryosphere changes on runoff components in basins with different cryosphere ratios. New hydrological insights for the regionTotal runoff (TR) increased in URSLH and URHH and decreased in URTLH, snowmelt runoff (SR) decreased in each basin, glacier runoff (GR) increased in URSLH and URTLH but decreased in URHH during 1980–2015. In the future, GR will increase under SSP585 and slightly decrease under SSP126 in 2040–2060 in URSLH and decrease in URHH and URSLH. The peak time of SR will advance by a month in each basin. In the future, GR (The ratio of the coefficient of variation (cv) of TR to cv of non-glacial runoff) will decrease, indicating hydrological regulation of glaciers will be weakened in these basins. SR and Rs (The ratio of summer runoff to spring runoff) will show downward trends, the processes of TR increase will be smoother. Rr (The ratio of maximum to minimum monthly runoff) will show downward trends under SSPs. TR will become smoother in each basin. Furthermore, the change of each runoff components will make TR tends to be smoother in the future and reduce TR especially in summer.

Central Asia's spatiotemporal glacier response ambiguity due to data inconsistencies and regional simplifications

Abstract. We have investigated the drivers behind the observed spatiotemporal mass balance heterogeneity in Tien Shan and Pamir, in High Mountain Asia. To study the consistency of the different interpretations derived from the available meteorological reanalysis and remote sensing products, we used correlation analyses between climatic and static drivers with novel estimates of region-wide annual glacier mass balance time series. These analyses were performed both spatially using different spatial classifications of glaciers and temporally for each individual glacier. Our results show that the importance of the variables studied depends strongly on the dataset used and which spatial classification of glaciers is chosen. This extends to opposing results using the different products. Even supposedly similar datasets lead to different and partly contradicting assumptions on dominant drivers of mass balance variability. The apparent but false consistencies across studies using a single dataset are related, according to our results, to the chosen dataset or spatial classification rather than to the processes or involved environmental variables. Without a glaciological, meteorological, and hydrological in situ observation network providing data that allow for the direct calibration and validation of extensive datasets, our understanding of neither the changing cryosphere at the regional scale for Tien Shan and Pamir nor glacier response to climate change or the assessment of water availability for the region’s growing population can improve.

Melting Alpine Water Towers Aggravate Downstream Low Flows: A Stress‐Test Storyline Approach

AbstractDroughts can lead to extreme low flow situations in rivers, with resulting severe impacts. Upstream snow and ice melt in many of the world's mountain water towers can alleviate the hydrological consequences of drought, yet global warming threatens the cryosphere. To improve the understanding of melt water contributions during drought in the case of future glacier retreat, we developed stress‐test storyline scenarios to model streamflow and tested them in the European river Rhine basin. Meteorological conditions of past drought and low flow years in Europe, 1976, 2003, and 2018, were repeated at three future moments in time, representing nowadays, near future and far future conditions. The latter two conditions were obtained by climate projections under the RCP8.5 scenario. Results show that the low flow situations caused by the meteorological drought situations aggravate in future conditions, more so for the far future and for the year 2003 because of the relatively large glacier ice melt contribution in the past. Summer (July–September) streamflow may decline by 5%–25% far downstream and 30%–70% upstream and the duration of extreme low flow situations may double compared to the selected past drought events. These results are relevant for the Rhine as a major European river but stand exemplary for many other river basins and highlight the importance of cryospheric changes for downstream low flow situations in a changing climate. The stress‐test scenarios allow a glimpse into future extreme low flow events aiding adaptation planning, and might be adapted to include other important low flow drivers.

The sensitivity and evolutionary trajectory of the mountain cryosphere: Implications for mountain geomorphic systems and hazards

AbstractGlobal climate change gives rise to changing spatial patterns of snow and ice, especially over mountain blocks where orographic and synoptic circulation effects play significant roles in creating patterns of precipitation and glacier development. The presence of snow and ice results in heat balance changes and other land surface feedbacks that have implications for patterns of mountain glacier retreat and the dynamics of mountain geomorphic systems. This study considers the sensitivity of the mountain cryosphere (snow, ice, permafrost) to global climate change, and the implications of this sensitivity analysis for evaluating mountain surface stability, geomorphic change, and the generation of mountain geohazards. Consideration of these issues is informed by evidence from case studies reported in the literature and by field observations of mountain system dynamics worldwide. Results show that ‘sensitivity’ to climate forcing has been interpreted and defined in different ways in mountain snow, ice, and permafrost systems, with respect to properties such as albedo, mass balance or rapidity of system change. There are also significant spatial differences in sensitivity between different mountain blocks for snow, ice and permafrost, and these regions are therefore likely to follow different trajectories of geomorphic change in response to climate forcing, related to their physiographic properties and the extent of cryospheric coverage. Within glaciated mountains in particular, the relative timing of different geomorphic events, and the interplay between slope, glacier front, and proglacial sediment sources and environments, may vary depending on glacier size, geomorphic setting, and microclimate. By contrast, responses to permafrost warming (increased surface instability and mass movements) and changes in snow patterns (avalanche risk, floods) may have quite different spatial and temporal patterns and influenced by different environmental controls. An integrated evolutionary model for mountain system development under a changing cryosphere is proposed, highlighting the critical role of energy balance as a forcing factor that then triggers downstream mountain system responses. This suggests that different elements of mountain systems exhibit different sensitivities, and furthermore that these sensitivities change over time and space through the period of anthropogenic global warming and paraglacial relaxation.

Contribution of cryosphere to runoff in the transition zone between the Tibetan Plateau and arid region based on environmental isotopes

Abstract. As the transition zone between the Tibetan Plateau and arid region, the Qilian Mountains are important ecological barriers and source regions of inland rivers in northwest China. In recent decades, drastic changes in the cryosphere have had a considerable impact on the formation process of water resources in the Qilian Mountains. In this study, 2164 environmental isotope samples were used to quantify the runoff components of 11 major rivers in the Qilian Mountains and investigate the influence of cryosphere changes on mountain runoff. The results show that the mountain runoff primarily originates in the cryosphere belt, which contributes approximately 82 %, 71 %, and 80 % to the Hexi inland water system, the upper stream of the Yellow River system, and the Qinghai inland river system, respectively. The maximum contribution ratio of glacier and snow meltwater to runoff occurred in May. The contribution of supra-permafrost water to runoff gradually increased from May and reached approximately 40 % in some rivers in October. Cryosphere degradation in the Qilian Mountains after the 1990s has caused a rapid increase in runoff, changes in the peak runoff time, and an increase in winter runoff. These changes in the hydrological processes bring opportunities and challenges to managing inland river water resources, and various adaptive measures to seek advantages and avoid disadvantages have been proposed. The findings from the environmental isotope analysis provide insights into understanding water resources and realizing the nexus of life, agriculture, industry, and ecological water use.

Exploiting the Combined GRACE/GRACE-FO Solutions to Determine Gravimetric Excitations of Polar Motion

Observations from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) missions can be used to estimate gravimetric excitation of polar motion (PM), which reflects the contribution of mass changes in continental hydrosphere and cryosphere to PM variation. Many solutions for Earth’s gravity field variations have been developed by institutes around the world based on GRACE/GRACE-FO data; however, it remains inconclusive which of them is the most reliable for the determination of PM excitation. In this study, we present a combined series of GRACE/GRACE-FO-based gravimetric excitation of PM computed using the three-cornered-hat (TCH) method, wherein the internal noise level in a combined solution is reduced to a minimum. We compare the combined series with results obtained from the combined GRACE/GRACE-FO solution provided by COST-G (International Combination Service for Time-variable Gravity Fields) and from the single solution elaborated by the Center for Space Research (CSR). All the gravimetric excitation series are evaluated by comparison with the sum of hydrological and cryospheric signals in geodetically observed PM excitation (called GAO). The results show that by minimizing the internal noise level in the combined excitation series using the TCH method, we can receive higher consistency with GAO than in the case of COST-G and CSR solutions, especially for the non-seasonal oscillations. For this spectral band, we obtained correlations between GAO and the best-combined series as high as 0.65 and 0.72 for the χ1 and χ2 equatorial components of PM excitation, respectively. The corresponding values for seasonal oscillation were 0.91 for χ1 and 0.89 for χ2. The combined series developed in this study explain up to 68% and 60% of overall GAO variability for χ1 and χ2, respectively.

Snow cover dynamics: an overlooked yet important feature of winter bird occurrence and abundance across the United States

Snow cover dynamics (i.e. depth, duration and variability) are dominant drivers of ecological processes during winter. For overwintering species, changes and gradients in snow cover may impact survival and population dynamics (e.g. facilitating survival via thermal refugia or limiting survival via reduced resource acquisition). However, snow cover dynamics are rarely used in species distribution modelling, especially for overwintering birds. Currently, we lack understanding of how snow cover gradients affect overwintering bird distributions and which functional traits drive these associations at regional and continental scales. Using observations from eBird, a global community science network, we explored the effects of snow cover dynamics on continental patterns of occurrence and counts for 150 bird species. We quantified the relative importance, species‐specific responses and trait‐based relationships of bird occurrence and abundance patterns to ecologically relevant snow cover dynamics across the United States. Snow cover dynamics were important environmental predictors in species distributions models, ranking within the top three predictors for most species occurrence (> 90%) and count (> 79%) patterns across the contiguous United States. Species exhibited a gradient of responses to snow cover from snow association to snow avoidance, yet most birds were limited by long, persistent snow seasons. Duration of winter and percent frozen ground without snow structured species distributions in the eastern USA, whereas snow cover variability was a stronger driver in the western USA. Birds associated with long, persistent snow seasons had traits associated with greater dispersal capacity and dietary diversity, whereas birds inhabiting regions with variable snow cover were generally habitat generalists. Our results suggest that various snow cover dynamics are important ecological filters of species distributions during winter. Global climate change is rapidly degrading key characteristics of seasonal snow cover. A changing cryosphere may elicit variable distributional changes for many overwintering birds, potentially accelerating range shifts and novel community assemblages.

An integrated index of cryospheric change in the Northern Hemisphere

The cryosphere plays an important role in the earth system and has experienced a dramatic and rapid decline due to climate change. Most cryospheric research focuses on changes in individual components, but there is no single metric that quantifies the cryosphere as a whole. We initially investigate 17 parameters representing various cryospheric components, and ultimately use principal component analysis on 13 of these variables to define an integrated index that quantifies cryospheric changes. Based on its strong negative correlation with air temperatures, we reconstruct the cryospheric index back to 1850, and also project it to 2100 using different climate model scenarios. An overall decrease is found in the cryospheric index, with interdecadal variability: an increase during 1940–1970, a subsequent strong decrease during the recent 50 years, and a projected fast decline in the future. We assess the associations between the cryospheric index and vegetation, greenhouse gases, and sea level rise. This cryospheric index represents an important new indicator of cryospheric and climatic change, that will be useful to compare against changes in other environmental variables. • 17 variables are identified to assess the 1984–2016 Northern Hemisphere cryosphere. • Principal component analysis combines 13 of the variables into a cryospheric index. • The index is reconstructed to 1850 and projected to 2100 based on air temperature. • Interdecadal variability dominates the index, with a strong decline starting ∼1970.

Dust dominates the summer melting of glacier ablation zones on the northeastern Tibetan Plateau

Dust and black carbon (BC) can darken snow and ice surface and play pivotal roles in glacier mass loss. Thus, a quantitative assessment of their contributions to glacier summer melting is critical. During the summer of 2018, surface snow and ice were sampled, and the albedo and mass balance were continuously measured in the ablation zone of Laohugou Glacier No. 12 in the western Qilian Mountains. The physical properties of dust and BC were measured in the laboratory, and their impacts on glacier surface albedo reduction and melting were simulated. The results indicate that the ice surface in the ablation zone was enriched with substantial amounts of particles, and the average particle concentrations of these samples were hundreds of times higher than those of fresh snow. The BC mass absorption cross-sections (MACs) ranged from 3.1 m2 g−1 at 550 nm for dirty ice to 4.6 m2 g−1 for fresh snow, largely owing to meltwater percolation and particle collapse. The spectral variations in dust MACs were significantly different in the visible light bands and near-infrared bands from those in the other areas. Moreover, the two-layer surface energy and mass balance model with the new albedo parameterization formula was validated and agreed well with the experimental measurements of spectral albedo, broadband albedo, and mass balance. BC and dust combined resulted in 26.7 % and 54.4 % of the total mass loss on the cleaner and dirtier (particle enriched) surfaces in the ablation zone, respectively, compared to particle-free surfaces, and although both impurities played vital roles, dust was the more prominent factor in accelerating glacier melting on the northeastern Tibetan Plateau. This study emphasizes the importance of dust in cryosphere changes where Tibetan glaciers are strongly affected by Asian dust deposition.

Solar-powered irrigation system as a nature-based solution for sustaining agricultural water management in the Upper Indus Basin

Rapid deglaciation in form of lowering of glacial surface under growing warm temperatures form a major cause of disruption in meltwater flows to cryosphere-fed irrigation network which usually affects the agriculture productivity and livelihoods in the Upper Indus Basin (UIB). In such hotspots of cryosphere change and other vulnerable areas, solar powered irrigation system (SPIS) can be adopted as a nature-based solution to uplift water from the nearby glacio-fluvial streams for irrigation and domestic use. In the present study, solar energy harnessing potential was investigated in the UIB region of Pakistan based on climate and topographic suitability to adopt solar powered irrigation system (SPIS) in the region. Overall mean temperature and elevation were found suitable for harnessing solar energy in major parts of the Hindu Kush-Karakoram-Himalaya (HKH) ranges of the UIB. The slope index indicated high suitability for harnessing solar energy in about 92.5% area, while aspect exhibited high suitability in about 13.3% area and medium in 25.3% area of the HKH region. The slope-aspect (SLA) suitability was found good in about 13.5% area of the Hindu Kush, 12% of the Karakoram and 10.9% area of the Himalaya range, whereas it was observed medium in about 26.7% area of the Hindu Kush, 21.8% of the Karakoram and 22.2% area of the Himalaya range. Overall the SLA suitability was found good in about 12.1% area and medium in about 23.5% area of the three HKH ranges. However, maximum benefits of the SPIS approach can be acquired through linking it with integrated water resource management approach for sustainable agricultural water management in the region.

Understanding Third Pole Atmospheric Dynamics and Land Surface Processes and Their Associations with the Cryosphere, Air Quality, and Climate Change

Understanding Third Pole Atmospheric Dynamics and Land Surface Processes and Their Associations with the Cryosphere, Air Quality, and Climate Change

Climate change and mercury in the Arctic: Biotic interactions

Global climate change has led to profound alterations of the Arctic environment and ecosystems, with potential secondary effects on mercury (Hg) within Arctic biota. This review presents the current scientific evidence for impacts of direct physical climate change and indirect ecosystem change on Hg exposure and accumulation in Arctic terrestrial, freshwater, and marine organisms. As the marine environment is elevated in Hg compared to the terrestrial environment, terrestrial herbivores that now exploit coastal/marine foods when terrestrial plants are iced over may be exposed to higher Hg concentrations. Conversely, certain populations of predators, including Arctic foxes and polar bears, have shown lower Hg concentrations related to reduced sea ice-based foraging and increased land-based foraging. How climate change influences Hg in Arctic freshwater fishes is not clear, but for lacustrine populations it may depend on lake-specific conditions, including interrelated alterations in lake ice duration, turbidity, food web length and energy sources (benthic to pelagic), and growth dilution. In several marine mammal and seabird species, tissue Hg concentrations have shown correlations with climate and weather variables, including climate oscillation indices and sea ice trends; these findings suggest that wind, precipitation, and cryosphere changes that alter Hg transport and deposition are impacting Hg concentrations in Arctic marine organisms. Ecological changes, including northward range shifts of sub-Arctic species and altered body condition, have also been shown to affect Hg levels in some populations of Arctic marine species. Given the limited number of populations and species studied to date, especially within Arctic terrestrial and freshwater systems, further research is needed on climate-driven processes influencing Hg concentrations in Arctic ecosystems and their net effects. Long-term pan-Arctic monitoring programs should consider ancillary datasets on climate, weather, organism ecology and physiology to improve interpretation of spatial variation and time trends of Hg in Arctic biota.