Winter Climatic Conditions Research Articles

Changes in waterbird occurrence and abundance at their northern range boundaries in response to climate warming: importance of site area and protection status

AbstractClimate warming is driving changes in species distribution, but habitat characteristics can interact with warming temperatures to affect populations in unexpected ways. We investigated wintering waterbird responses to climate warming depending on habitat characteristics, with a focus on the northern boundary of their non‐breeding distributions where winter climatic conditions are more extreme. At these Nordic latitudes, climate warming is expected to drive positive changes in species occurrence and abundance, with likely differences in species‐specific responses. We analyzed the occurrence and abundance of 18 species of waterbirds monitored over 2,982 surveys at 245 inland wetlands over a 25‐year period in Sweden. We used hierarchical modeling of species communities (HMSC) which enabled us to relate species‐specific changes to both functional traits and phylogenetic relatedness. We investigated occurrence and abundance changes in response to average temperature, temperature anomalies, site area, site protection status (Natura 2000), and land use in agricultural and urban surfaces. Unsurprisingly, both average temperatures and temperature anomalies were the most important variables influencing positively waterbird occurrence and abundance. For 60% of the species, the effect of temperature anomalies was even stronger in large or protected wetlands. Geese and mallard occurred more often at sites surrounded by agricultural and urban surfaces, respectively, but their occurrence in these habitats was not affected by interactive effects with climate warming. Species abundance was greater inside protected areas only for 11% of the species, but occurrence probability was higher inside protected areas for 44% of the species. Overall, we observed that species thermal affinity was a strong predictor for positive species response to temperature anomalies, and that species sharing similar phylogenetic history had similar relationships with environmental variables. Protection of large wetlands and restoration of the surrounding habitats are two targets for climate change adaptation strategies to facilitate future responses of waterbirds to climate warming.

A self-satisfying cooling system based on cold energy storage for the locomotive in a high geothermal tunnel

Effective thermal management of locomotive systems is crucial for ensuring the safe operation of trains through high geothermal tunnels. By taking advantage of the frequent alternation of high-temperature tunnels and cold climate environment, a self-satisfying cooling system based on cold energy storage is proposed, in which a phase change heat exchanger between air and phase change material (succinic acid with 20 wt% expanded graphite) is developed to store cold energy outside tunnels and improve air-cooling efficiency inside tunnels. Numerical models are established to examine the thermal environment in a typical tunnel and the effectiveness of the proposed cooling system. The results indicate that because of the heat exhausted from the train and the thermal dissipation from the surrounding hot rock, the air temperature in the tunnel can rise above 50 °C. The proposed cooling system can release the cold energy from phase change material to keep the air outlet temperature below 40 °C, increasing the energy efficiency and reliability of locomotive operation. By examining the effects of locomotive operating conditions and orthogonal analysis of multi-factors, the heat exchanger structure and other operating conditions are recommended for the self-satisfying cooling system. Finally, the cooling system’s effectiveness is confirmed for the full-line operation of the locomotive along the Ya’an-Nyingchi section of the Sichuan-Tibet Railway in both summer and winter climatic conditions. This study is significant because it provides a novel design scheme for locomotive’s thermal management in high geothermal tunnels and other similar engineering conditions with natural cold sources.

Regional variation in branch morphological and physical traits in Abies sachalinensis associated with winter climatic conditions

ABSTRACT In boreal forests, overwintering strategies, including snow adaptation, can be expected in the branches of coniferous trees. Although it is difficult to detect resistance to snow disturbances and few studies have quantified the functional traits related to snowfall resistance, the regional variation associated with winter conditions may provide cues for identifying adaptive traits against snow damage. In common garden trials, we examined the regional variation in branch functional traits in Abies sachalinensis, one of the most important conifers in boreal forest silviculture. Morphological traits reflecting susceptibility to snow accumulation, such as branch estimated area, Young’s modulus and flexural rigidity, which represent deformability to snow loads, and base diameter and xylem density were evaluated in five-year-old branches from eight provenances. The length and estimated area of a branch showed regional variation. Significant regional variation in flexural rigidity rather than Young’s modulus and no significant correlation between xylem density and mechanical traits indicated that the physical properties of branches depend on their size rather than on their materials. A significant correlation with winter climatic conditions was observed between flexural rigidity and total monthly precipitation in January. Our results showed that the thicker the branch is, the larger the branch area and the more rigid it is. This indicates that the branch size-dependent resistance to snow loads might be associated with winter adaptation to local snowfall conditions.

ISOSCAPES AND PALEOISOTHERMS OF THE HOLOCENE MEAN JANUARY AIR TEMPERATURE IN THE NORTHWESTERN SIBERIA (BASED ON STABLE OXYGEN ISOTOPE COMPOSITION OF ICE WEDGES)

Holocene ice wedges at 16 sites in the Northwestern Siberia were studied, the age of ice wedges was determined, and stable isotope data ( 18O and 2Н values) for all studied ice wedges have been summarized. The δ2H-δ18O ratio and the dexc values for ice wedge ice indicate good preservation of the isotope signal of winter precipitation in ice, which allows to use the obtained δ18O values for paleotemperature reconstructions. The isoscapes (lines of equal 18O values) created for the Holocene ice wedges and modern ice veinlets are generally submeridional; the 18O values decrease from west to east of the study area. Taking into account a new Holocene tripartite division scheme it was shown that the mean January air temperature (TmJ) in the Northwestern Siberia ranged approximately from -21 to -30°С during Greenlandian and the first half of the Northgrippian stage of the Holocene (11,4 to 6 cal ka BP) and approximately from -24 to -27°С from the end of the Northgrippian - to the Meghalayan stage of the Holocene (5,2 to 0,9 cal ka BP). The Holocene isotherms are close to the modern sub-meridional position and show an eastward decrease in TmJ values. Winter climatic conditions in the Northwestern Siberia were generally stable during the Holocene, meanwhile TmJ was on average 1-2°C lower than modern ones.

An improved crop calendar model for winter wheat incorporating vernalization and winter survival to project changes in phenology

Crop phenology and associated crop calendars are necessary for designing breeding goals and for developing effective management practices. Winter wheat is a representative biennial, the cultivation schedule of which is constrained by winter climate conditions, particularly the processes of vernalization and winter survival. Here, we present improvements to a rule-based crop calendar model by incorporating these factors so that it can be used to accurately estimate the phenological events of winter wheat from daily meteorological data. We tested the improved model in Hokkaido, the northernmost Japanese island, which is characterized by seasonal snow cover and a wet summer. The results confirmed that implementing these factors contributed to accurate estimates of peak occurrence dates of winter wheat phenological events. Furthermore, we applied the improved model to simulate wheat phenology under 2 K and 4 K warmer scenarios. The results showed a delayed sowing period up to approximately one month and slight advancements in both flowering and harvesting, leading to a shorter growth period. While this shortened period may be largely compensated by a decrease in the snow-covered period, the shifts in the vegetative and reproductive phases may modify sink-source balance of wheat. We also assessed the risks of pollination failure and preharvest sprouting, both of which are associated with the timing of precipitation, based on the number of rainy days around flowering, and the incidence of precipitation over two consecutive days around the time of harvesting. Our simulations suggested increased risk of pollination failure and reduced risk of preharvest sprouting, leading to an increase in the probability of crop failure. These findings underscore the importance of implementing adaptation measures to mitigate precipitation-related risk under future climates. Further, the findings provide valuable insights for winter wheat breeders and agronomists, thereby facilitating crop production adaptation.

Целесообразность применения цифровых трамваев на шинах в городах России

Objective: show the prospects of using an innovative type of public urban transport - a digital tram on tires with optical guidance along a strip marked on the road or using magnetic markers along the route, as attractive to passengers, cheaper in the arrangement of lines, as well as requiring less time to build than rail tram for urban transportation, allowing to relieve city roads from traffic jams and improve their ecology. Methods: an analysis and generalization of the operating experience of new digital trams built by the Chinese company CRRC, operated in the cities of China: Zhuzhou, Yibin, Yongxiu, Yancheng and Shanghai, as well as the most advanced designs of the operating rolling stock. Results: the operation of the tire tram revealed a number of problems: after a year of operation, severe rutting appeared on a dedicated lane of the road, speeds and capacity were lower than declared. The construction of new tire tram lines required costs for strengthening the roadway, which was not originally intended by the manufacturer. The possibility of their use in winter climate conditions on roads covered with ice and snow has not been proven. Further testing is required to identify and eliminate emerging deficiencies. Practical significance: despite a number of identified shortcomings, it is advisable to use a digital tire tram for cities with a warm climate, with complex terrain and narrow streets as a medium-capacity vehicle that can improve the mobility and quality of life of citizens, as well as reduce the negative impact on the environment. It is advisable to lay it in new residential areas and industrial zones under construction, as well as to use it for mass transportation of passengers in the event of any major one-time events: major exhibitions, forums, Olympic Games, world football championships, etc.

Taking the beat of the Arctic: are lemming population cycles changing due to winter climate?

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.

Design and Performance Analysis of an Air-Based Photovoltaic/Thermal Collector in Winter

The most basic needs of the buildings in which we spend almost all of our time are electricity and heat demands. Especially in cold climatic regions, it is very important that both electrical energy and heating energy demand are met through the same system. The use of photovoltaic (PV), is increasing rapidly. Photovoltaic panels can transform solar energy into electrical energy with less than 20% performance. Photovoltaic-thermal(PV/T) collectors which can be mounted on facades of buildings or used as building envelopes, are one of the solar energy applications. With this collector, both electric energy and thermal energy demand is produced from solar energy. In our work, Photovoltaic panel and some kind of solar air collector have been taken into consideration. In order to determine the behavior of the air-based photovoltaic-thermal collector, an experimental setup and a measurement system have been established. The experimental setup consists of this measurement system, sensors that obtain data, and a data storage unit that can transmit temperature, humidity, and radiation data to the computer at the desired frequency. In order to determine the performance of the air-based PV/T collector, the efficiencies of both the PV and the solar air collector were calculated separately. To determine the performance of this collector, calculation criteria’s and model has been determined. When creating this model, the problem has been considered as time-dependent under irregular conditions. The theoretical analysis model, which was established to determine the performance of the air-based PV/T collector, was evaluated according to the winter climatic conditions of Izmir-Turkey.

Local factors and sources affecting freshwater chloride concentrations in the Toronto region

Increasing chloride concentrations in freshwater streams throughout many areas of North America have raised concern over freshwater salinization. Road salt has been implicated; however, chloride source identification is lacking in the Toronto region. We assessed trends in chloride concentrations in streams and groundwater between 2000 and 2021 within the Toronto region and identified factors contributing to trends. Chloride concentrations increased in 36 of 47 streams and in 5 of 13 groundwater wells. There were no significant relationships between changes in stream chloride concentrations and changes in winter climatic conditions over the study period; however, changes in stream chloride concentrations were positively related to changes in road density. Chloride:bromide ratios indicated that road salt and/or septic effluent was the dominant source of chloride in streams. Inputs varied throughout the year with road salt and/or septic effluent having a higher proportion of inputs during the salting season compared to the non-salting season where a higher proportion of inputs were from basin brines and/or animal waste, landfill leachate, and pristine aquifer. Commercial, industrial, institutional, and medium density residential land uses were also positively correlated with stream chloride. Parking lot cover increased in several catchments suggesting that these too may contribute to trends. These results highlight the importance of continued and enhanced investment in long-term monitoring of freshwater ecosystems. It also highlights the need for urgent action to better control and monitor road salt usage by public and private applicators since urban growth continues to drive increasing chloride trends.

Do city lockdowns effectively reduce air pollution?

Severe air pollution remains a problem in developing countries such as India and China owing to unfavourable winter climate conditions that encourage the diffusion of air pollutants. Although city lockdowns can alleviate serious air pollution, they incur significant social costs. This study explored the effect of China's COVID-19 lockdown on air pollution. Machine learning was utilised to eliminate weather-related fluctuations in air pollutant concentrations, and two difference-in-difference models were employed to estimate the effects of general epidemic prevention and enhancement measures on air pollution and evaluate the total impact of city lockdown on air pollutant concentrations. By carefully examining the proportion of these effects in the overall impact, this study analysed the cost-effectiveness of city-level lockdown measures on air pollution. Results indicate that city lockdowns significantly reduced the concentrations of five air pollutants: NO2 (−28.3 %), PM10 (−21.41 %), PM2.5 (−15.83 %), CO (−8.66 %), and SO2 (−4.2 %). The contributions of the enhancement measures are 41.82 % for PM2.5, 42.66 % for PM10, −4.04 % for CO, and 31.83 % for NO2. This suggests that city lockdowns may not be cost-effective compared to general epidemic prevention measures. Thus, this study recommends limited city lockdown measures for severe air pollution, similar to the general epidemic prevention measures.

Heat load-carrying capacity of surface water source and its heating load matching characteristics

Meteorological parameter changes not only affect the heat load-carrying capacity of the surface water, but also affect the heat load demand of the building, thus changing the heat load matching between the water source heat pump system and the users. In order to study the climatic adaptation of the heat load-carrying capacity, this paper establishes an analytical model of the water body's heat load-carrying capacity and the building's heat load with the solar radiation intensity, the change of the water body and the heat extraction time as variables. Experimental and simulation studies on the heat load-carrying capacity of lake water were carried out under the winter climate conditions in hot summer and cold winter areas. The results show that increasing the depth or area of the lake can improve the heat load-carrying capacity. Solar radiation is an important factor affecting the temperature of surface water body, the stronger the solar radiation the greater the temperature rise of the water body. Changes in outdoor air temperature have a significant impact on water temperature, and a sudden drop in outdoor air temperature will result in a sharp drop in water temperature. When the water body area was 3000 m2 and 50000 m2, the maximum integrated temperature drop of the water body was 15.0℃ and 9.7℃, which was 2.02 and 4.85 times of the temperature drop of heat extraction, respectively. Reduced heat load-carrying capacity of the surface water body or decreased COP of the heat pump is an important reason why the surface water source heat pump heat supply fails to meet the user's heat demand in winter.

Frost Resistance of Redispersible Polymer Powder–Modified Fast-Hardening Cement Mortars under Simulated Climatic Conditions

Polymer-modified fast-hardening cement mortar is widely used as road repair material due to its excellent performance attributes of shorter setting time and good workability as well as high adhesive strength. However, in the complex actual service environment, whether it can still maintain stable performance has become a concern. Therefore, this study performed an indoor freeze–thaw cycle test to investigate the frost resistance of polymer-modified fast-hardening cement mortar under winter climate conditions in Lanzhou. The macro properties of the fabricated mortar were characterized by compressive strength and flexural strength, and the microstructures were investigated by MIP, FTIR, and SEM. It was found that with increasing polymer doses, the frost resistance of the fast-hardening cement mortar was improved, and the flexural strength increased gradually, but the compressive strength showed an opposite evolutionary trend. The overall performance of mortars was best when the content of polymer admixture was 4%, by mass, of the cementitious material. In addition, the polymer significantly refined the pore structure in the range of 3–10 nm, which made the total porosity of the system increase. Meanwhile, the polymer could be involved in the chemical reaction to generate polymer film and interlap with the needlelike ettringite (AFt) to form a spatial network structure, as shown by FTIR and SEM analysis. This means that incorporating polymer 5010N improved the microstructure of the fast-hardening cement mortar, leading to improved frost resistance.

Ecological and life‐history traits predict temporal trends in biomass of boreal moths

Abstract Dramatic insect declines, and their consequences for ecosystems globally, have received considerable attention recently. Yet, it is still poorly known if ecological and life‐history traits can explain declines and whether insect decline occurs also at high latitudes. Insects' diversity and abundance are dramatically lower at high latitudes compared to the tropics, and insects might benefit from climate warming in high‐latitude environments. We adopted a trait‐ and biomass‐based approach to estimate temporal change between 1993 and 2019 in Finnish macro‐moth communities by using data from 85 long‐running light traps. We analysed spatio‐temporal variation in biomass of moth functional groups with Joint Dynamic Species Distribution Models while accounting for environmental variables. We did not detect any declining trends in total moth biomass of moth functional groups, and most groups were stable over time. Moreover, biomass increased for species using coniferous trees, lichens, or mushrooms as hosts, multivoltine species, as well as monophagous and oligophagous species feeding on trees. We found that length and temperature of the growing season, winter climatic conditions, and habitat structure all partially explained variation in moth biomass. Although boreal moth communities are rapidly changing due to species turnover, in terms of total biomass they seem to contradict the trend of dramatic insect declines observed globally. This may lessen the immediate possibility of negative bottom‐up trophic cascades in boreal food webs.

RMIc-3.0 Program Development to Prioritize Concrete Pavement Sections for Large-scale Repair Works

Large-scale repair works (LSRW) are expensive and time-consuming, and therefore cannot be carried out simultaneously for all deteriorated pavements; hence, they are performed based on urgency. In Korea, the re-modeling index (RMI) program versions 1.0 and 2.0 were developed to predict the urgency of the LSRW on expressway concrete pavements. In this study, version 3.0 of the RMI program was developed to address the drawbacks found in version 2.0 of the program. The model used in the program was improved by using the equivalent single-axle load instead of the annual average daily traffic used in the previous version, to consider the damage to pavement caused by heavy vehicles. In addition, another model was modified by combining the winter climate conditions with the annual deicing salt usage, which was used as the only variable considering the environmental factors in the previous version. The international roughness index and surface distress prediction models, which were not separated by pavement type in version 2.0 of the program, were separated into jointed concrete pavement and continuously reinforced concrete pavement. The logic for predicting future RMI was also reasonably improved. In addition, the logic of categorizing the entire expressway concrete pavement section into homogeneous sections was objectively improved for more effective LSRW. Consequently, for 2023, the Korea Expressway Corporation selected for LSRW those homogeneous sections that were evaluated as urgent by the RMI3.0 program.

Enhancing the performance of an unglazed solar air collector using mesh tubes and Fe3O4 nano-enhanced absorber coating

In the current article, it is intended to improve the performance of an unglazed solar air collector using mesh tubes as extended heat transfer surfaces and nano-enhanced black paint as a thermal conductivity booster of the absorber coating material. In this regard, three types of unglazed solar air collectors have been designed, produced and simultaneously tested containing a conventional (unmodified) system, a system with only mesh tube modification and a system with combined usage of mesh tubes and nano-enhanced absorber coating. It should be stated that Fe3O4 nanoparticles have been utilized within the scope of this work. Integrating nanoparticles to the absorber coating material (industrial matt black paint) averagely improved the thermal conductivity as 0.031 W/mK. The experimental process was tested at fixed air flow rate (0.0115 kg/s) in winter climatic conditions. As result of the experimental analysis, average thermal efficiency values were attained between 45.11 and 63.36%. Combined usage of mesh tubes and nano-enhanced black paint upgraded the mean thermal performance as 40.45% in comparison to the unmodified system. Also, obtained exergetic efficiencies are in the range of 5.49–9.96%. In addition to the energy-exergy analysis, enviro-economic survey was performed within the scope of the current work. Payback periods of the analyzed systems were found between 0.31 and 0.34 years.

Winter survival of adults of two geographically distant populations of Aedes albopictus in a microclimatic environment of Athens, Greece

Overwintering capacity is a major step towards establishment of invasive mosquitoes from the tropics in temperate zone areas and one of the main elements determining next seasons’ population size that regulates disease transmission of competent invasive vector species. The Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culiciidae) is an aggressive invasive species that has greatly expanded its geographical boundaries over the last few decades. The species’ ability to induce photoperiodic-based egg diapause allows its overwintering in temperate regions, which favors its establishment in higher latitudes. In warmer temperate areas winter survival can be accomplished in the adult stage as well especially in human-made shelters. Aedes albopictus is already showing signs of adaptation to colder climates which may result in disease transmission in new areas. Although the Asian tiger mosquito has invaded Greece since 2003–4, little is known regarding its overwintering capacity in the country, especially as far as adults are regarded. We studied the survival of Ae. albopictus adults during winter in a protected shelter in Athens, the capital city of Greece. The study involved two geographically isolated populations originating from Chania (Crete, most southern part of Greece), and Palaio Faliro (Athens, Central Greece). We exposed different cohorts of F3 adults of the above two populations that emerged from field collected eggs to “winter condition” from November 2018 to beginning of January 2019. in a protected microclimatic environment. Adult mortality was recorded systematically until the death of the last individual in the cohort. Results demonstrated evidence of winter survival of adults for both populations. Longevity of both females and males of the Palaio Faliro population was longer than that of the Chania population for almost all installation dates. Survival curves, regardless of the date of installation, were steeper for females of the Chania population compared to those from Palaio Faliro. In conclusion, overwinter survival of both populations in the adult stage highlights the need for future studies, considering local and microclimatic condition that vary significantly between regions. Winter climatic conditions play vital role in adult survival of this highly important public health species concerning distribution limits and knowledge on winter survival of Ae. albopictus transmitted viruses.

Chytridiomycosis and climate change: exposure to Batrachochytrium dendrobatidis and mild winter conditions do not increase mortality in juvenile agile frogs during hibernation

AbstractHibernation is often associated with high mortality, especially during early life stages, and losses can be exacerbated by unusual winter conditions or if animals enter hibernation carrying a disease. Here, we examined how overwintering amphibians may be affected by the combined effects of mild winters, which are projected to increase in frequency due to climate change, and of chytridiomycosis, a disease that has contributed to the decline of hundreds of species worldwide. We exposed juvenile agile frogs Rana dalmatina to Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, and subsequently subjected them to either a long, cold winter (1.5°C for 91 days) or a short, mild winter (4.5°C for 61 days) under laboratory conditions. Agile frogs proved to be highly resistant to Bd as only 37% of Bd‐exposed individuals became infected as determined before hibernation, and prevalence further decreased to 8% by the end of hibernation, with individuals showing very low infection intensity values. We observed lack of mortality in control and Bd‐exposed groups also, in both types of winter. The two types of winter we simulated did not result in differing body mass loss either alone or in combination with experimental infection. In the Bd‐exposed group, the two types of winter also did not cause differences in prevalence and infection intensity. However, among Bd‐exposed frogs, individuals that were Bd negative when entering hibernation lost more body mass than their conspecifics that carried the fungus at the onset of overwintering. Based on our results, warming winter climate conditions, with or without Bd infection, do not decrease body mass and survival rate of hibernating agile frogs, and do not increase susceptibility of individuals to chytridiomycosis. It remains to be seen to what extent the relatively weak effects of milder winters can be generalized to other amphibians of the temperate climate zone.

Holocene January paleotemperature of northwestern Siberia reconstructed based on stable isotope ratio of ice wedges

AbstractIce wedges are considered as a paleoarchive of winter air temperatures as their stable isotope composition has been widely used to reconstruct winter climatic conditions in the Arctic regions. Ice wedge stable isotope records, obtained in recent decades for many Arctic permafrost areas of Russia and North America, demonstrate a clear shift from lower to higher values between the Late Pleistocene and Holocene (by 5–10‰ for δ18O values in some regions of the Russian Arctic), which is widely accepted as evidence of winter air temperature increase. However, the evolution of winter air temperatures during the Holocene is less clear and, according to proxy reconstructions, winter climate trends are not synchronous and may significantly vary throughout the Arctic. In this study, we investigate the stable isotope composition of Holocene syngenetic ice wedges and modern ice veinlets of northwestern Siberia. Radiocarbon dating of enclosing sediments and a few dates of organic material from ice wedges demonstrate that ice wedges grew constantly within the study area during the Holocene though early–mid‐Holocene in northwestern Siberia is often considered as a thermal optimum. In fact, many proxy records indicate an increase of summer air temperatures followed by thermokarst activity, peatland formation, and northward advance of the treeline. According to our data, winter climate conditions in terms of mean air temperature of the coldest winter month (January) did not change significantly during the key Holocene stages, and during the Greenlandian and most of the Northgrippian stages (between 11.4 and 6 cal ka BP) mean January air temperature (TmJ) varied between −21 and −30°C, and from the end of the Northgrippian, during the Meghalayan stages of Holocene (5.2–0.9 cal ka BP), TmJ varied between −24 to −28°C. Mean January air temperature during the Holocene was generally 1–2°C lower than the modern one, meanwhile the submeridional direction of TmJ isotherms and eastward decrease of TmJ values in Holocene are similar to the modern pattern.

Changing winter climate and snow conditions induce various transcriptional stress responses in Scots pine seedlings.

In northern boreal forests the warming winter climate leads to more frequent snowmelt, rain-on-snow events and freeze-thaw cycles. This may be harmful or even lethal for tree seedlings that spend even a half of the year under snow. We conducted a snow cover manipulation experiment in a natural forest to find out how changing snow conditions affect young Scots pine (Pinus sylvestris L.) seedlings. The ice encasement (IE), absence of snow (NoSNOW) and snow compaction (COMP) treatments affected ground level temperature, ground frost and subnivean gas concentrations compared to the ambient snow cover (AMB) and led to the increased physical damage and mortality of seedlings. The expression responses of 28 genes related to circadian clock, aerobic and anaerobic energy metabolism, carbohydrate metabolism and stress protection revealed that seedlings were exposed to different stresses in a complex way depending on the thickness and quality of the snow cover. The IE treatment caused hypoxic stress and probably affected roots which resulted in reduced water uptake in the beginning of the growing season. Without protective snowpack in NoSNOW seedlings suffered from cold and drought stresses. The combination of hypoxic and cold stresses in COMP evoked unique transcriptional responses including oxidative stress. Snow cover manipulation induced changes in the expression of several circadian clock related genes suggested that photoreceptors and the circadian clock system play an essential role in the adaptation of Scots pine seedlings to stresses under different snow conditions. Our findings show that warming winter climate alters snow conditions and consequently causes Scots pine seedlings various abiotic stresses, whose effects extend from overwintering to the following growing season.

Performance analysis of a solar-driven integrated direct-contact membrane distillation and humidification–dehumidification system

Despite significant advantages of solar-driven membrane-based distillation systems, their large-scale application is limited due to high energy losses, and low technical and economic feasibility. To overcome the mentioned issues, a Direct-Contact Membrane Distillation (DCMD) module (as the primary distillation stage) was coupled with a hollow-fibre membrane-based air humidification–dehumidification (HD) unit (as the secondary distillation stage) to increase the water productivity of the system by recovering some of the lost energy in the first stage. The membrane-based humidifier was designed and implemented instead of the conventional packed columns to avert their drawbacks of being bulky, complex, less durable, and less reliable. An accurate and effective multi-step model was developed for modelling the integrated system considering the changing nature of thermo-physical properties. The suggested system was then built and tested in Perth, Western Australia. Experiments were conducted to determine the technical efficacy of incorporating the distillation from the second stage and its effects on freshwater production rate, gained output ratio, and overall efficiency of the integrated system. The results clearly indicated that the proposed two-stage system outperformed the conventional standalone solar DCMD and HD systems. The energy recovery unit was effective by increasing the average freshwater production by 34 % and 33 % for the replicated temperatures representing typical summer and winter climate conditions of Perth, respectively. The improvement in gained output ratio and coefficient of performance were observed to be 36 % and 38 %, and 26 % and 28 % for summer and winter temperatures, respectively. Moreover, the optimised air velocity of HD systems was found to be 1 m/s and the results indicated that the water production of the HD system at the considered flow rates (2–5 Lpm) was not sensitive to feed temperature at low values (<50 °C).