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Reports of fading vole and lemming population cycles and persisting low populations in some parts of the Arctic have raised concerns about the spread of these fundamental changes to tundra food web dynamics. By compiling 24 unique time series of lemming population fluctuations across the circumpolar region, we show that virtually all populations displayed alternating periods of cyclic/non-cyclic fluctuations over the past four decades. Cyclic patterns were detected 55% of the time (n = 649 years pooled across sites) with a median periodicity of 3.7 years, and non-cyclic periods were not more frequent in recent years. Overall, there was an indication for a negative effect of warm spells occurring during the snow onset period of the preceding year on lemming abundance. However, winter duration or early winter climatic conditions did not differ on average between cyclic and non-cyclic periods. Analysis of the time series shows that there is presently no Arctic-wide collapse of lemming cycles, even though cycles have been sporadic at most sites during the last decades. Although non-stationary dynamics appears a common feature of lemming populations also in the past, continued warming in early winter may decrease the frequency of periodic irruptions with negative consequences for tundra ecosystems. [ABSTRACT FROM AUTHOR]

We analyzed long-term measurements of organic carbon, elemental carbon, and source-specific organic tracers from 2017 to 2020 to constrain carbonaceous aerosol sources in the rapidly changing Arctic. Additionally, we used absorption photometer (Aethalometer) measurements to constrain equivalent black carbon (eBC) from biomass burning and fossil fuel combustion, using positive matrix factorization (PMF). Our analysis shows that organic tracers are essential for understanding Arctic carbonaceous aerosol sources. Throughout 2017 to 2020, levoglucosan exhibited bimodal seasonality, reflecting emissions from residential wood combustion (RWC) in the heating season (November to May) and from wildfires (WFs) in the non-heating season (June to October), demonstrating a pronounced interannual variability in the influence of WF. Biogenic secondary organic aerosol (BSOA) species (2-methyltetrols) from isoprene oxidation was only present in the non-heating season, peaking in July to August. Warm air masses from Siberia led to a substantial increase in 2-methyltetrols in 2019 and 2020 compared to 2017 to 2018. This highlights the need to investigate the contribution of local sources vs. long-range atmospheric transport (LRT), considering the temperature sensitivity of biogenic volatile organic compound emissions from Arctic vegetation. Tracers of primary biological aerosol particles (PBAPs), including various sugars and sugar alcohols, showed elevated levels in the non-heating season, although with different seasonal trends, whereas cellulose had no apparent seasonality. Most PBAP tracers and 2-methyltetrols peaked during influence of WF emissions, highlighting the importance of measuring a range of source-specific tracers to understand sources and dynamics of carbonaceous aerosol. The seasonality of carbonaceous aerosol was strongly influenced by LRT episodes, as background levels are extremely low. In the non-heating season, the organic aerosol peak was as influenced by LRT, as was elemental carbon during the Arctic haze period. Source apportionment of carbonaceous aerosol by Latin hypercube sampling showed mixed contributions from RWC (46 %), fossil fuel (FF) sources (27 %), and BSOA (25 %) in the heating season. In contrast, the non-heating season was dominated by BSOA (56 %), with lower contributions from WF (26 %) and FF sources (15 %). Source apportionment of eBC by PMF showed that FF combustion dominated eBC (70±2.7 %), whereas RWC (22±2.7 %) was more abundant than WF (8.0±2.9 %). Modeled BC concentrations from FLEXPART (FLEXible PARTicle dispersion model) attributed an almost equal share to FF sources (51±3.1 %) and to biomass burning. Both FLEXPART and the PMF analysis concluded that RWC is a more important source of (e)BC than WF. However, with a modeled RWC contribution of 30±4.1 % and WF of 19±2.8 %, FLEXPART suggests relatively higher contributions to eBC from these sources. Notably, the BB fraction of EC was twice as high as that of eBC, reflecting methodological differences between source apportionment by LHS and PMF. However, important conclusions drawn are unaffected, as both methods indicate the presence of RWC- and WF-sourced BC at Zeppelin, with a higher relative BB contribution during the non-heating season. In summary, organic aerosol (281±106 ng m -3) constitutes a significant fraction of Arctic PM 10 , although surpassed by sea salt aerosol (682±46.9 ng m -3), mineral dust (613±368 ng m -3), and typically non-sea-salt sulfate SO 42- (314±62.6 ng m -3), originating mainly from anthropogenic sources in winter and from natural sources in summer. [ABSTRACT FROM AUTHOR]

Our current understanding of Arctic carbonaceous aerosol (CA) is rudimentary and there is a lack of long-term observations for many components, such as organic aerosol (OA), exceptions to this include equivalent black carbon (eBC) and methane sulfonic acid (MSA). To address this, we analyzed long-term measurements of organic carbon (OC), elemental carbon (EC), and source-specific organic tracers from 2017 to 2020 to constrain CA sources in the rapidly changing Arctic. We also used absorption photometer (aethalometer) measurements to constrain equivalent BC from biomass burning (eBCBB) and fossil fuel combustion (eBCFF) using Positive Matrix Factorization (PMF). Our analysis showed that organic tracers are essential to understand Arctic CA sources. For 2017 to 2020, levoglucosan had a bimodal seasonality, with a signal from residential wood combustion (RWC) in the heating season (H-season; November to May) and from wildfires (WF) in the non-heating season (NH-season; June to October), demonstrating a pronounced inter-annual variability in the WF influence. Biogenic secondary organic aerosol (BSOA) species (2-methyltetrols) from isoprene oxidation appeared only in the NH-season, peaking in July to August. Intrusions of warm air masses from Siberia in summer caused three- and ninefold increases in 2-methyltetrols compared to 2017 to 2018, in 2019 and 2020, respectively, warranting investigation of the local vs. the long-range atmospheric transport (LRT) contribution, as certain Arctic vegetation has highly temperature sensitive biogenic volatile organic compounds (BVOC) emission rates. Primary biological aerosol particles (PBAP) tracers (various sugars and sugar-alcohols) were elevated in the NH-season but evolved differently, whereas cellulose was completely decoupled from the other PBAP tracers. Peak levels of most PBAP tracers and of 2-methyltetrols were associated with WF emissions, demonstrating the importance of measuring a broad spectrum of source specific tracers to understand sources and dynamics of CA. Finally, CA seasonality is heavily influenced by long-range atmospheric transport (LRT) episodes, since background levels are extremely low. E.g., we find the OA peak in the NH-season is as strongly influenced by LRT as is EC during Arctic Haze (AH). Source apportionment of CA by Latin Hypercube Sampling (LHS) showed a mixed contribution from RWC (46 %), fossil fuel (FF) sources (27 %), and BSOA (25 %) in the H-season, whereas BSOA (56 %) prevailed over WF (26 %) and FF (15 %) in the NH-season. Source apportionment of eBC by PMF showed that FF combustion dominated eBC (70 ± 2.7 %), whereas RWC (22 ± 2.7 %) was more abundant than WF (8.0 ± 2.9 %). Modeled BC concentrations from FLEXPART attributed an almost equal share to FF (51 ± 3.1 %) and BB. Both FLEXPART and the PMF analysis concluded that RWC is a more important source than WF. However, with a modeled RWC of 30 ± 4.1 % and WF of 19 ± 2.8 %, FLEXPART suggests relatively higher contributions to eBC from these sources. We find that OA (281 ± 106 ng m−3) is a significant fraction of the Arctic PM10 aerosol particle mass, though less than sea salt aerosol (SSA) (682 ± 46.9 ng m−3) and mineral dust (MD) (613 ± 368 ng m−3) as well as typically non-sea-salt sulfate (nssSO42−) (314 ± 62.6 ng m−3), originating mainly from anthropogenic sources in winter and from natural sources in summer. FF combustion was the prevailing source of eBC, whereas RWC made a larger contribution to eBCBB than WF. [ABSTRACT FROM AUTHOR]

The Greater Barents Sea Basin (GBSB) in Arctic Russia and Norway is an intracratonic basin that accommodated an enormous amount of sediment during the Triassic. These deposits are up to 4.5 km thick over an area 2,500,000 km2, and consist of marine mudstones and mudstone-rich fluvio-deltaic topsets with sandstone-dominated fluvial channels. The basin is well-studied and data-rich, but regional correlation between different parts is lacking. Provenance data from adjacent Arctic basins have been interpreted to imply sediment transport from the Ural orogen across the GBSB, but these are disputed because of great transport distances, poorly constrained sediment-transport directions and unknown timing of bypass. We integrated data from 3,238 seismic lines, 257 wells and palynostratigraphy, as well as published outcrop data, to create the first unified stratigraphic framework for the Triassic deposits across the entire GBSB. Results show that (1) sediment was transported northwest by one linked sedimentary system stretching across the entire basin; (2) sediment was derived from a source in the east comprising the Urals and West Siberia; (3) the main stratigraphic boundaries are major flooding surfaces which can be traced throughout the basin; and (4) significant amounts of sediment overspilled from the Barents Sea into adjacent sedimentary basins, starting with the Lomonosov Ridge from the Early Triassic, and into basins to the northwest (e.g. Sverdrup, Chukotka) during the late Carnian. These results provide a better understanding of geodynamics and provenance data in the Arctic, to improve the prediction of reservoirs in the area, and indicate a protracted uplift-history of the northernmost Urals that started in the Carnian ~237 Ma. Furthermore, it shows how large intracratonic basins interact with uplands and subside over tens of millions of years. [ABSTRACT FROM AUTHOR]

The Arctic sea-ice is retreating faster than predicted by climate models and could become ice free during summer this century. The reduced sea-ice extent may effectively "unlock" the Arctic Ocean to increased human activities such as transit shipping and expanded oil and gas production. Travel time between Europe and the north Pacific Region can be reduced by up to 50 % with low sea-ice levels and the use of this route could increase substantially as the sea-ice retreats. Oil and gas activities already occur in the Arctic region and given the large undiscovered petroleum resources increased activity could be expected with reduced sea-ice. We use a bottom-up shipping model and a detailed global energy market model to construct emission inventories of Arctic shipping and petroleum activities in 2030 and 2050 given estimated sea-ice extents. The emission inventories are on a 1 x 1 degree grid and cover both short-lived components (SO2, NOx, CO, NMVOC, BC, OC) and the long-lived greenhouse gases (CO2, CH4, N2O). We find rapid growth in transit shipping due to increased profitability with the shorter transit times compensating for increased costs in traversing areas of sea-ice. Oil and gas production remains relatively stable leading to reduced emissions from emission factor improvements. The location of oil and gas production moves into locations requiring more ship transport relative to pipeline transport, leading to rapid emissions growth from oil and gas transport via ship. Our emission inventories for the Arctic region will be used as input into chemical transport, radiative transfer, and climate models to quantify the role of Arctic activities in climate change compared to similar emissions occurring outside of the Arctic region. [ABSTRACT FROM AUTHOR]

The rapidly changing Arctic marine ecosystems face new challenges and opportunities that are increasing and shifting governance needs in the region. A group of economists, ecologists, biologists, political scientists and resource managers met in Stockholm, SE, Sept 4–6, 2014 to discuss the governance of Arctic marine resources in a spatial context. We report on the findings here. [ABSTRACT FROM AUTHOR]

More than a quarter of the world's carnivores are threatened, often due to multiple and complex causes. Considerable research efforts are devoted to resolving the mechanisms behind these threats in order to provide a basis for relevant conservation actions. However, even when the underlying mechanisms are known, specific actions aimed at direct support for carnivores are difficult to implement and evaluate at efficient spatial and temporal scales., We report on a 30-year inventory of the critically endangered Fennoscandian arctic fox Vulpes lagopus L., including yearly surveys of 600 fox dens covering 21 000 km2. These surveys showed that the population was close to extinction in 2000, with 40-60 adult animals left. However, the population subsequently showed a fourfold increase in size., During this time period, conservation actions through supplementary feeding and predator removal were implemented in several regions across Scandinavia, encompassing 79% of the area. To evaluate these actions, we examined the effect of supplemental winter feeding and red fox control applied at different intensities in 10 regions. A path analysis indicated that 47% of the explained variation in population productivity could be attributed to lemming abundance, whereas winter feeding had a 29% effect and red fox control a 20% effect., This confirms that arctic foxes are highly dependent on lemming population fluctuations but also shows that red foxes severely impact the viability of arctic foxes. This study also highlights the importance of implementing conservation actions on extensive spatial and temporal scales, with geographically dispersed actions to scientifically evaluate the effects. We note that population recovery was only seen in regions with a high intensity of management actions., Synthesis and applications. The present study demonstrates that carnivore population declines may be reversed through extensive actions that target specific threats. Fennoscandian arctic fox is still endangered, due to low population connectivity and expected climate impacts on the distribution and dynamics of lemmings and red foxes. Climate warming is expected to contribute to both more irregular lemming dynamics and red fox appearance in tundra areas; however, the effects of climate change can be mitigated through intensive management actions such as supplemental feeding and red fox control. [ABSTRACT FROM AUTHOR]

Lemmings are involved in several important functions in the Arctic ecosystem. The Arctic fox ( Vulpes lagopus) can be divided into two discrete ecotypes: 'lemming foxes' and 'coastal foxes'. Crashes in lemming abundance can result in pulses of 'lemming fox' movement across the Arctic sea ice and immigration into coastal habitats in search for food. These pulses can influence the genetic structure of the receiving population. We have tested the impact of immigration on the genetic structure of the 'coastal fox' population in Svalbard by recording microsatellite variation in seven loci for 162 Arctic foxes sampled during the summer and winter over a 5-year period. Genetic heterogeneity and temporal genetic shifts, as inferred by STRUCTURE simulations and deviations from Hardy-Weinberg proportions, respectively, were recorded. Maximum likelihood estimates of movement as well as STRUCTURE simulations suggested that both immigration and genetic mixture are higher in Svalbard than in the neighbouring 'lemming fox' populations. The STRUCTURE simulations and AMOVA revealed there are differences in genetic composition of the population between summer and winter seasons, indicating that immigrants are not present in the reproductive portion of the Svalbard population. Based on these results, we conclude that Arctic fox population structure varies with time and is influenced by immigration from neighbouring populations. The lemming cycle is likely an important factor shaping Arctic fox movement across sea ice and the subsequent population genetic structure, but is also likely to influence local adaptation to the coastal habitat and the prevalence of diseases. [ABSTRACT FROM AUTHOR]

In Svalbard, Norway, the only intermediate host for Echinococcus multilocularis, the sibling vole, has restricted spatial distribution. A survey of feces from the main host, the arctic fox, showed that only the area occupied by the intermediate host is associated with increased risk for human infection. [ABSTRACT FROM AUTHOR]

The changing climate in the Arctic opens new shipping routes. A shift to shorter Arctic transit will, however, incur a climate penalty over the first one and a half centuries. We investigate the net climate effect of diverting a segment of Europe-Asia container traffic from the Suez to an Arctic transit route. We find an initial net warming for the first one-and-a-half centuries, which gradually declines and transitions to net cooling as the effects of CO2 reductions become dominant, resulting in climate mitigation only in the long term. Thus, the possibilities for shifting shipping to the Arctic confront policymakers with the question of how to weigh a century-scale warming with large uncertainties versus a long-term climate benefit from CO2 reductions. [ABSTRACT FROM AUTHOR]