Arctic warming will promote Atlantic–Pacific fish interchange

Brown carbon from biomass burning imposes strong circum-Arctic warming

The strategic partnership between China and Russia is creating solid ground for the cooperative development of the Arctic. These two states'joint development of the Northern Sea Route will not only provide additional impulse to the export-oriented economy of China and allow further diversification of supply routes to China, but will also promote investment into the infrastructure and economic growth of Russian northern territories. Climate change in the Arctic has forced China and Russia to acknowledge the sustainable use of the Arctic. On the one hand, exploration of the region should not harm indigenous people's rights and should help this population improve their standard of living by providing qualified healthcare and opportunities for commercial fulfillment of traditional crafts. On the other hand, this exploration should also include elimination of harmful anthropogenic impact and provide support for environment self-restoration. Sino-Russian Arctic cooperation will help humans discover eco-friendly approaches to use Arctic resources, promote rational use of the Arctic and inspire sustainable development of the region. Citation: Bai J Y, Voronenko A. Lessons and prospects of Sino-Russian Arctic cooperation. Adv Polar Sci, 2016, 27: 185-191, doi: 10.13679/j.advps.2016.3.00185

The behaviour of water between the surface and subsurface is a dynamic and intricate process, involving a complex interplay between surface water and groundwater. This interaction is vital for supporting ecosystems, providing water supplies, and ensuring the sustainable use of water resources. Disruptions in these interactions, such as over-extraction, reduced streamflow, and the impacts of climate change, contribute to water scarcity. An integrated management of surface and groundwater resources is crucial for addressing these challenges and ensuring the long-term availability and sustainability of water supplies. In this study, the spatiotemporal variations of surface and groundwater interactions were analysed using integrated SWAT and MODFLOW model using QSWATMOD plugin in QGIS software. The surface and groundwater interactions were analysed for future periods under climate and land use land cover (LULC) change scenarios. Pre-monsoon, monsoon, post-monsoon kharif, and post-monsoon rabi seasons are considered for analysing the surface and groundwater interactions. The future LULCs are projected using the DynaCLUE model for three user-defined scenarios such as past trend (scenario 1), drastic change in built-up and barren land (scenario 2), and restricted agricultural land (scenario 3). For projecting the interactions under both changing climate and LULC, LULC scenario 1 was used for near-future period, LULC scenario 2 for mid-future period, and LULC scenario 3 for far future period. Under the climate change scenario, the maximum groundwater recharge under SSP5-8.5 scenario is observed to be 20,805 m3/day in the near future, and the maximum discharge under SSP2-4.5 scenario is observed as 9,035 m3/day in the mid-future period. In both climate change and combined scenarios (both climate and user-defined LULC), there was a greater recharge of groundwater during the monsoon season relative to other seasons, while there was a greater discharge of groundwater during the post-monsoon rabi season. In the combined scenarios, the maximum discharge was under SSP5-8.5 with 15,009 m3/day in the mid-future, and the groundwater recharge was greater in the near future period under SSP3-7.0 with 19,556 m3/day. The groundwater–surface water interactions were analysed in four seasons, out of which monsoon season had the maximum recharge and groundwater discharge was more in the post-monsoon rabi season. The results found in this study’ can be used to plan and develop short-and long-term integrated surface and groundwater management strategies of the basin under changing climate and LULC.

Ocean warming and species exploitation have already caused large-scale reorganization of biological communities across the world. Accurate projections of future biodiversity change require a comprehensive understanding of how entire communities respond to global change. We combined a time-dynamic integrated food web modeling approach (Ecosim) with previous data from community-level mesocosm experiments to determine the independent and combined effects of ocean warming, ocean acidification and fisheries exploitation on a well-managed temperate coastal ecosystem. The mesocosm parameters enabled important physiological and behavioral responses to climate stressors to be projected for trophic levels ranging from primary producers to top predators, including sharks. Through model simulations, we show that under sustainable rates of fisheries exploitation, near-future warming or ocean acidification in isolation could benefit species biomass at higher trophic levels (e.g., mammals, birds, and demersal finfish) in their current climate ranges, with the exception of small pelagic fishes. However, under warming and acidification combined, biomass increases at higher trophic levels will be lower or absent, while in the longer term reduced productivity of prey species is unlikely to support the increased biomass at the top of the food web. We also show that increases in exploitation will suppress any positive effects of human-driven climate change, causing individual species biomass to decrease at higher trophic levels. Nevertheless, total future potential biomass of some fisheries species in temperate areas might remain high, particularly under acidification, because unharvested opportunistic species will likely benefit from decreased competition and show an increase in biomass. Ecological indicators of species composition such as the Shannon diversity index decline under all climate change scenarios, suggesting a trade-off between biomass gain and functional diversity. By coupling parameters from multilevel mesocosm food web experiments with dynamic food web models, we were able to simulate the generative mechanisms that drive complex responses of temperate marine ecosystems to global change. This approach, which blends theory with experimental data, provides new prospects for forecasting climate-driven biodiversity change and its effects on ecosystem processes.

The Arctic has witnessed significant sea ice melt and rising temperatures as major indicators of climate system alterations. As a severe weather event conveying heat and moisture from lower latitudes to the higher, atmospheric rivers (ARs) can lead to significant sea ice loss and Arctic warming. Sea ice thickness is applied in this study to quantitatively explore the thermodynamic and dynamic impacts of ARs in winters from 2000 to 2020. ARs from the North Atlantic (AAR) and North Pacific (PAR) account for 44% of AR events and 40% of AR-driven sea ice loss. The AR-induced melting process occurs in three successive stages. In stage I, warm, moist air driven by dipole circulation anomalies ahead of AR causes sea ice melting, with thermal effects accounting for 53% for AAR and 58% for PAR. Stage II starts when the AR enters the Arctic and ends as its moisture transport weakens. Early sea ice loss is driven by wind dynamics, while poleward progression elevates warm, moist air, forming clouds that intensify melting thermodynamically. This stage sees the most significant sea ice melt, dominated by dynamic effects for AAR (59%) and thermodynamic effects for PAR (55%).In stage III, as AR moisture dissipates, sea ice melt continues for about a week, primarily driven by thermodynamic effects. Accompanied by the above three stages, the anticyclonic circulation anomaly on the right side of where AR is headed can also enhance downdrafts and melt perennial ice. By contrast, Pacific-channel ARs have a higher impact on the central Arctic than their Atlantic counterparts, suggesting extensive responses to climate variability. Significance Statement The aim of this study was to clarify the thermodynamic and dynamic effects of atmospheric rivers (ARs) on the melting of Arctic sea ice. We discovered that 44% of AR events, channeled through North Atlantic and Pacific routes, are responsible for 40% of sea ice melting. Notably, the melting process caused by ARs generally comprises three successive stages: Thermal melting is predominant in the first stage, the second stage begins when the main body of the AR enters the Arctic and leads to the most dramatic sea ice melt, which is mainly caused by dynamic effect in Atlantic sector and thermal dynamic effect in Pacific sector. In the last stage, the weakened sea ice decreases mainly caused by the thermodynamic effect with the dispersion of the AR moisture. A dipole-type circulation anomaly was found to exacerbate dynamic melting and sustain thermal melting in both the edge zone of the ice cap and the central Arctic. These findings emphasize the impact of ARs on the climate sensitivity of the Arctic region.

Article reports observations of two Subarctic North Pacific puffin species in the North Atlantic near the coast of north-west Greenland.

Persistent anomalies (PAs) are associated with a variety of impactful weather extremes, prompting research into how their characteristics will respond to climate change. Previous studies, however, have not provided conclusive results, owing to the complexity of the phenomenon and to difficulties in general circulation model (GCM) representations of PAs. Here, we diagnose PA activity in ten years of current and projected future output from global, high-resolution (15-km mesh) time-slice simulations performed with the Model for Prediction Across Scales-Atmosphere (MPAS-A). These time slices span a range of ENSO states. They include high-resolution representations of sea-surface temperatures and GCM-based sea ice for present and future climates. Future projections, based on the RCP8.5 scenario, exhibit strong Arctic amplification and tropical upper warming, providing a valuable experiment with which to assess the impact of climate change on PA frequency. The MPAS-A present-climate simulations reproduce the main centers of observed PA activity, but with an eastward shift in the North Pacific and reduced amplitude in the North Atlantic. The overall frequency of positive PAs in the future simulations is similar to that in the present-day simulations, while negative PAs become less frequent. Although some regional changes emerge, the small, generally negative changes in PA frequency and meridional circulation index indicate that climate change does not lead to increased persistence of midlatitude flow anomalies or increased waviness in these simulations.

Human interference with the climate system is occurring, and climate change poses risks for human and natural systems (IPCC, 2014). In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Evidence of climate-change impacts is strongest and most comprehensive for natural systems. Due to climate change projected by the mid 21st century and beyond, global marine-species redistribution and marine-biodiversity reduction in sensitive regions will challenge the sustained provision of fisheries productivity and other ecosystem services (IPCC, 2014). Spatial shifts of marine species due to projected warming will cause high-latitude invasions and high local-extinction rates in the tropics and semi-enclosed seas. Species richness and fisheries catch potential are projected to increase, on average, at mid and high latitudes and decrease at tropical latitudes (IPCC, 2014). The Benguela Current Large Marine Ecosystem (BCLME) is one of four Eastern Boundary Upwelling Ecosystems (EBUE), highly productive marine subregions. Although they comprise <2% of the global ocean area, they contribute nearly 7% of marine primary production and more than 20% of the world’s marine capture fisheries (IPCC, 2014). Catches in the EBUE are dominated by planktivorous species such as sardine, anchovy, and horse/jack mackerel, and piscivorous demersal species such as hake. Upwelling of nutrient-rich water stimulates primary production which is transferred to mid and upper trophic levels, resulting in substantial fish, seabird, and marine mammal populations. As a result, EBUEs are considered ‘hotspots’ of productivity and biodiversity. Previous research on the BCLME has had little emphasis on climate change. As with the other EBUEs, strong inter-annual and inter-decadal variability in physical oceanography makes it challenging to detect biophysical trends attributed to climate change. Nevertheless, the physical conditions of the BCLME are highly sensitive to climate variability over a range of scales. Despite its apparent sensitivity to environmental variability, there is limited evidence of ecological changes in the BCLME caused by climate change (IPCC, 2014). For example, pelagic fish, benthic crustaceans, and seabirds have demonstrated general shifts in distribution (IPCC, 2014). Even though much of the evidence on the recent climate change comes from remote sensing and outputs from coupled atmosphere-ocean models, it is necessary to link the global trends with local observations to detect the effects of this change on marine living resources in a regional context. In the BCLME region, the combined oceanographic and biodiversity database collected through the Ecosystem Approach to Fisheries (EAF) Nansen Programme is potentially a major source of local data covering climate change and its effect on marine resources in the last 30 yr. However, its contributions to the understanding of climate change effects on the BCLME are rather limited so far, since the huge amount of data collected under the programme has not been fully utilised. Based on data collected through the EAF Nansen programme, together with other relevant data, the NansClim project (2009–2014) was established to identify and describe possible trends and variability in ocean climate and corresponding changes in marine biodiversity and fisheries in the Benguela Current System. Observations of effects of climate variability on marine biota in the past, based on the Nansen database in combination with other data series available from the region, allowed NansClim to document some general responses concerning production and distribution of marine biota to set a baseline of observed effects of climate variability. Some of the species in the region are more poorly studied than others, and one of the tasks of the project was therefore to characterize the life cycle of such species which may be important indicators of future climate change.

Consequent Effects of Parasitism on Population Dynamics, Food Webs, and Human Health Under Climate Change

The Arctic Regions have been a fascinating subject of study for a long time, mainly because of man’s strong desire to conquer the unknown. The military interest in those regions did not develop until recent years. With the straining of relations between the Soviet Union and the United States after World War II, the strategic significance of the Arctic soon became very real. This significance was appreciably diminished with the invention of intercontinental ballistic missiles but the more recent development of the nuclear missile-launching submarine has given the Arctic waters a new military importance. Of course, nuclear submarines could also be of considerable commercial interest. By borrowing the Arctic Ocean, merchant submarines could drastically shorten some of the present maritime trading routes. The exploitation of natural resources in the Arctic regions is already in process of giving new commercial meaning to the old Northwest and Northeast Passages. In the circumstances, an inquiry into the legal regime of the Arctic waters is timely. Two basic principles of the law of the sea are involved: the right of innocent passage, and the freedom of the seas. The present study will concentrate on the right of innocent passage. An investigation will be made into the legal status of the Arctic waters constituting what is commonly known as the Northwest Passage, on the North American side of the Pole, and the Northeast Passage or Northern Sea Route on the Soviet side. The basic question is whether or not the right of free and innocent passage in favour of foreign ships applies to those waters.

Currently, three stocks of sei whales (Balaenoptera borealis) are defined in the North Atlantic; the Nova Scotian, Iceland-Denmark Strait and Eastern North Atlantic stocks, which are mainly based upon historical catch and sighting data. We analyzed mitochondrial control region DNA (mtDNA) sequences and genotypes from 7 to 11 microsatellite loci in 87 samples from three sites in the North Atlantic; Iceland, the Gulf of Maine and the Azores, and compared against the North Pacific using 489 previously published samples. No statistically significant deviations from homogeneity were detected among the North Atlantic samples at mtDNA or microsatellite loci. The genealogy estimated from the mtDNA sequences revealed a clear division of the haplotypes into a North Atlantic and a North Pacific clade, with the exception of one haplotype detected in a single sample from the Azores, which was included in the North Pacific clade. Significant genetic divergence between the North Atlantic and North Pacific Oceans was detected (mtDNA ΦST = 0.72, microsatellite Weir and Cockerham’s ϴ = 0.20; p < 0.001). The coalescent-based estimate of the population divergence time between the North Atlantic and North Pacific populations from the sequence variation among the mtDNA sequences was at 163,000 years ago. However, the inference was limited by an absence of samples from the Southern Hemisphere and uncertainty regarding mutation rates and generation times. The estimates of inter-oceanic migration rates were low (Nm at 0.007 into the North Pacific and at 0.248 in the opposite direction). Although estimates of genetic divergence among the current North Atlantic stocks were low and consistent with the extensive range of movement observed in satellite tagged sei whales, the high uncertainty of the genetic divergence estimates precludes rejection of multiple stocks in the North Atlantic.

Abstract. Streams are natural features in urban landscapes that can provide ecosystem services for urban residents. However, urban streams are under increasing pressure caused by multiple anthropogenic impacts, including increases in human population and associated impervious surface area, and accelerated climate change. The ability to anticipate these changes and better understand their effects on streams is important for developing and implementing strategies to mitigate potentially negative effects. In this study, stream flow was monitored during April–November (2011 and 2012), and the data were used to apply the Storm Water Management Model (SWMM) for five urban watersheds in central Iowa, USA, representing a gradient of percent impervious surface (IS, ranging from 5.3 to 37.1%). A set of three scenarios was designed to quantify hydrological responses to independent and combined effects of climate change (18% increase in precipitation), and land cover change (absolute increases between 5.2 and 17.1%, based on separate projections of impervious surfaces for the five watersheds) for the year 2040 compared to a current condition simulation. An additional set of three scenarios examined stream response to different distributions of land cover change within a single watershed. Hydrological responses were quantified using three indices: unit-area peak discharge, flashiness (R-B Index; Richards–Baker Index), and runoff ratio. Stream hydrology was strongly affected by watershed percent IS. For the current condition simulation, values for all three indices were five to seven times greater in the most developed watershed compared to the least developed watershed. The climate change scenario caused a 20.8% increase in unit-area peak discharge on average across the five watersheds compared to the current condition simulation. The land cover change scenario resulted in large increases for all three indices: 49.5% for unit-area peak discharge, 39.3% for R-B Index, and 73.9% for runoff ratio, on average, for the five watersheds. The combined climate and land cover change scenario resulted in slight increases on average for R-B Index (43.7%) and runoff ratio (74.5%) compared to the land cover change scenario, and a substantial increase, on average, in unit area peak discharge (80.1%). The scenarios for different distributions of land cover change within one watershed resulted in changes for all three indices, with an 18.4% increase in unit-area peak discharge for the midstream scenario, and 17.5% (downstream) and 18.1% (midstream) increases in R-B Index, indicating sensitivity to the location of potential additions of IS within a watershed. Given the likelihood of increased precipitation in the future, land use planning and policy tools that limit expansion of impervious surfaces (e.g. by substituting pervious surfaces) or mitigate against their impacts (e.g. by installing bioswales) could be used to minimize negative effects on streams.

We studied regional effects of alternative climate change and management scenarios on timber production, its economic profitability (net present value (NPV), with 2% interest rate), and carbon stocks over a 90 year simulation period in Norway spruce (Picea abies (L.) Karst.) forests located in southern, central, and northern Finland. We also compared the results of optimised management plans (maximizing incomes) and fixed management scenarios. Business as usual (BAU) management recommendations were used as the basis for alternative management scenarios. The forest ecosystem model SIMA together with a forest optimisation tool was employed. To consider the uncertainties related to climate change, we applied two climate change scenarios (SRES B1 and SRES A2) in addition to the current climate. Results showed that timber production, NPV, and carbon stocks of forests would reduce in southern Finland, opposite to northern Finland, especially under the strong climate change scenario (SRES A2) compared with the current climate. In central Finland, climate change would have little effect. The use of optimised management plans also resulted in higher timber yield, NPV, and carbon stock of forests compared with the use of a single management scenario, regardless of forest region and climate scenario applied. In the future, we may need to modify the current BAU management recommendations to properly adapt to the changing climatic conditions.

Both climate and agricultural policy changes are commonly seen as important drivers for agricultural production. In this study, scena-rios of climate and political change were calculated for the Upper Danube catchment area using the regional optimization model ACRE. Two political scenarios were calculated for the year 2020. One scenario assumes the continuation of the Common Agricultural Policy reform 2003 the other assumes a strong shift away from payments of the first pillar to payments of the second pillar of the CAP. Both scenarios were combined with four different scenarios of climate change and technological progress derived from ICCP SRES assumptions and the ACCELERATES project. The results of the scenario calculations were analysed with respect to their implica-tions for the whole catchment area as well as for selected districts. Climate change and technological progress both cause small changes in agricultural land use: fodder crop area tends to be converted to cash crop area, and intensive grasslands tend to be converted into extensive grasslands. Climate change and technological progress increase crop productivity, and consequently, total gross margin increases. The impact of climate change might get stronger toward the end of the century which is beyond the scope of the investigations presented here. The impact of climate change might thus switch from bringing net benefits in the short to medium term to bringing net losses for the area investigated in the long run.

Production suitability of date palm under changing climate in a semi-arid region predicted by CLIMEX model