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Many global climate models (GCMs) have difficulty in simulating climate variabilities over high northern latitudes. One of the main reasons is the inability of GCMs to simulate proper cloud fraction and the amount of liquid-containing cloud over the region. This study assessed the impact of cloud simulation in high latitudes by comparing the long-term parallel simulations of Community Atmosphere Model version 6 (CAM6) and CAM5, the previous version. The results show that the CAM6 simulation exhibits a considerable improvement in the Arctic, especially by reducing the cold bias of CAM5 throughout the year. Over the sub-Arctic region, however, CAM6 produces an excessive cold bias in summer and a warm bias in winter compared to the observation, which is closely related to the overestimation of cloud fraction and the amount of cloud liquid. In summer, the overestimation of the cloud in CAM6 tends to alleviate the cold bias compared to CAM5 due to an increase in downward longwave radiation over the high latitudes, while causing the excessive cold bias by blocking downward shortwave radiation over the sub-Arctic land area. In winter, when there is little incidence of shortwave radiation, the overestimation of the cloud in CAM6 increases the downward longwave radiation, which alleviates the cold bias in CAM5 over the Arctic but induces an excessive warm bias over the sub-Arctic land. The excessive cloudiness in CAM6 could weaken the high-latitude internal variability, exacerbating the deteriorating climate variability and long-term trend simulations in the region. [ABSTRACT FROM AUTHOR]

Arctic regions support a wide variety of freshwater ecosystems. These naturally oligotrophic and cold‐water streams, rivers, ponds and lakes are currently being impacted by a diverse range of anthropogenic pressures, such as accelerated climate change, permafrost thaw, land‐use change, eutrophication, brownification and the replacement of northern biota with the range expansion of more southern species.Multiple stressors are rapidly changing Arctic freshwater systems as aquatic habitats are becoming more suitable for species originating from more southerly regions and thereby threatening biota adapted to cold waters. The livelihoods of Indigenous Peoples of the north will be altered when ecosystem services associated with changes in biodiversity are affected. Unfortunately, monitoring of biodiversity change in Arctic freshwaters is currently inadequate, making it difficult, if not impossible, to predict changes in ecosystem services.Synthesis and applications. We propose a three‐step approach to better address and facilitate monitoring of the rapid ecological changes that Arctic freshwater ecosystems are currently experiencing as a result of climate change. First, we should increase our efforts in the monitoring of freshwaters across all Arctic countries by setting up a network of monitoring sites and devoting more effort to a broad‐scale baseline survey using standardized methods. Second, we should enhance modelling efforts to include both ecological change and socio‐economic development. These models should help pinpoint species, ecosystems and geographical areas that are likely to show abrupt changes in response to any changes. Third, we should increase interaction among scientists, policymakers and different stakeholder groups. In particular, Indigenous Peoples must be involved in the leadership, planning and execution of monitoring and assessment activities of Arctic freshwaters. The proposed approach, which is critical to detecting the effects of climate change in the circumpolar region, has broader applications for global coordination of Arctic freshwater biomonitoring. Through routine monitoring, standardization of methods, enhanced modelling of integrated scientific and socio‐economic change, and increased collaboration within and among sectors, more effective monitoring and management of climate change impacts on freshwater biodiversity will be possible in the Arctic and globally. [ABSTRACT FROM AUTHOR]

The paper aimed at estimating the significance of paleoenvironmental changes in the process of the prehistorical human dispersals over Northern Eurasia, and particularly his penetration to the High Latitudes. As follows from the recent investigations, the northeastern part of Europe appears to be settled earlier than it has been supposed until recently. The traces left by the early man in the European Arctic may be dated to 40 000 to 35 000 years BP (43096 to 40159 cal. BP). The Siberian North was colonized in the Late Pleistocene. The materials recovered from the Yanskaya site (71°N) provide evidence of human survival in the Arctic regions of Eastern Siberia at least ca. 28 to 27 ka BP (32780 ± 660 to 31170 ± 520 cal. BP). Valleys in the middle reaches of the Lena and Aldan rivers were populated after 24 000 yr BP (28165 cal. BP). We may identify two main directions in the High Latitude colonization between 40 000 to 12 000 yr BP [43096 to 13907 cal. BP], namely along the basins of the Kama and Pechora rivers in Eastern Europe and by way of the Lena and Yana basins in Northern Asia. West Siberia and the Northeastern Asia were actively populated at the Late Glacial time; the same period was marked by the first human penetration from the Eastern to Western hemisphere (from the Chukchi Peninsula to Alaska) by the 'Bering Land Bridge'. The northernmost regions of the East Siberia, such as Taymyr Peninsula and the New Siberian Islands (Zhokhov Island), were inhabited in the early and middle Holocene. [ABSTRACT FROM AUTHOR]

Different components of global change (e.g., climate change, land use, pollution, and introduced species) continue to alter biodiversity worldwide. As northern regions are still relatively undisturbed and will likely face clear increases in temperature in the near-future, we examined the signs of biodiversity change due to anthropogenic stressors using a systematic review of previous studies. Our aim was to map where, in which way, and owing to which stressor biodiversity in northern regions has changed. We made a systematic literature search covering the years between 2000 and 2015 to obtain a comprehensive selection of recent research. As species richness was clearly the most commonly used indicator of biodiversity, we only concentrated on this aspect of biodiversity. We compared different biological groups, regions, and ecosystems. In the majority of the cases, anthropogenic stressors had decreased species richness, or had no effects on it, while increasing or multiple effects of stressors on species richness were less common. Freshwater ecosystems were most sensitive to anthropogenic stressors, as species richness often decreased owing to these stressors. The effects of land use on richness were covered relatively widely in the selected set of articles, but the effects of other components of global change on species richness require further attention. Despite the fact that pollution was not as commonly studied stressor as land use, it was the most harmful stressor type affecting species richness. Geographically, most studies were located in boreal Canada or Fennoscandia, while no studies were executed in vast circumpolar areas where the temperature rise has been greatest and the projected climate change is likely to be fast. Overall, we could find an alarmingly small set of studies that described the effects of actual anthropogenic stressors in real-life circumstances in northern high latitudes. [ABSTRACT FROM AUTHOR]

Abstract: We compared tree-ring width (TRW) and maximum latewood density (MXD) chronologies to remotely sensed indices of productivity (NDVI) and snowmelt since 1981 and to the instrumental temperature record at four arctic treeline sites in North America. Our results show that at these sites, TRW chronologies reflect temperatures less consistently than the MXD chronologies do and that the NDVI does not correlate significantly with TRW at high-frequency, i.e. when comparing yearly values. In contrast, the MXD chronologies correlate positively and significantly with NDVI and temperature during the growing season at all sites. Neither TRW or MXD chronologies appeared consistently influenced by the annual timing of snowmelt. A comparison of tree-ring chronologies and temperatures since 1900 confirms that MXD has tracked growing season temperature at these treeline sites throughout the past century. A spatial evaluation of the correlations further reveals that each of the MXD chronologies investigated here reflects interannual variation in NDVI and growing season temperatures across a large geographic region. As a result, they collectively provide a spatially comprehensive record of historic early-season canopy status as well as growing season temperatures for the high latitudes of North America. [Copyright &y& Elsevier]

The article discusses a paper which examines the climatic and related environmental changes in the Arctic regions and its impacts in Eurasia, as well as to human activities, economic development, and national security. It outlines various manifestations of Arctic climate warming such as the reduction of the permafrost zone and reduced Arctic ice cap thickness. It suggests that climate change directly affect Eurasia and thus need to respond economically and socially to environmental changes.