Annual Air Temperature Research Articles

Temperature and nutrients control the presence and distribution of long-chain diols in Swiss lakes

Long-chain diols are biomarkers commonly used in the marine realm to reconstruct several environmental parameters such as sea surface temperature and salinity. However, they are also produced in lacustrine and slow-flowing river environments, a characteristic that has proved to be useful to trace past riverine inputs in coastal sedimentary records. So far, their use in lacustrine settings is sparse as their controls are not well-known. Previous studies in two lakes have shown that long-chain diol distribution is linked to changes in temperature (in a small Spanish alpine lake), but also to water column stratification (in a large deep Swiss lake). To understand the controls on i) the presence of long-chain diols in lakes, and ii) the distribution of long-chain diol isomers, surface sediments from 52 Swiss lakes were studied. Long-chain diols are present in 57% of the lakes, and machine learning (i.e., random forest model) showed that their presence is mainly controlled by mean annual air temperature, sodium and potassium concentrations and area of the lakes. Long-chain diol isomer relative distribution seems to react to temperature, nutrient (here nitrate) and oxygen concentrations in the lakes. This new insight was tested on a short sedimentary core from Lake Zurich, and compared with other biomarker proxies (based on branched and isoprenoid glycerol dialkyl glycerol tetraethers), as well as with historical record of nutrient contents and temperature. Variations in the long-chain diol index (LDI) mirror measured temperature, but also reacted to changes in nutrients and oxygenation in the lake. This study highlights the potential of long-chain diols as a proxy to trace both nutrients and temperature in lakes, potentially on geological timescales.

Assessment of branched glycerol monoalkyl glycerol tetraether (brGMGT)-based paleothermometry in the 250,000-year sediment record of Lake Chala, equatorial East Africa

Branched glycerol monoalkyl glycerol tetraethers (brGMGTs), a relatively understudied group of bacterial membrane lipids structurally similar to branched glycerol dialkyl glycerol tetraethers (brGDGTs), appear to be strongly influenced by temperature in terrestrial settings. In surficial bottom sediments of East African lakes, the abundance of brGMGTs relative to the sum of brGMGTs and brGDGTs (%brGMGT) and brGMGT distribution are strongly related to local mean annual air temperature (MAAT), stimulating development of new paleothermometers. However, applications of these methods to lake-sediment records are currently lacking. Here we investigate brGMGT concentrations and distributions in 916 samples throughout the 250,000-year (250-kyr) sediment sequence from Lake Chala, a presently fresh and permanently stratified (meromictic) tropical crater lake. All seven previously identified brGMGTs occur abundantly, reflected in a relatively high average %brGMGT of 19%. BrGMGTs and brGDGTs concentrations throughout the sequence are strongly correlated (R = 0.83, p < 0.001), suggesting that their producers and/or associated ecological niches substantially overlap. Clear distinction can be made between brGMGTs produced predominantly in the bottom sediments (H1034a and H1034c) versus the anoxic lower water column (H1020a-c and H1034b). Although a 17-month monitoring study of Lake Chala suggested brGMGTs are primarily produced in the sediments, down-core data assign greater importance to aquatic production than previously estimated. Instead of reflecting temperature, %brGMGT variations showed greatest similarity to GDGT proxies reflecting lake depth and/or mixing regime. BrGMGT-based temperature models produce ambiguous reconstructions, showing little similarity to known global temperature trends or the brGDGT-based mean summer temperature (MST) reconstruction from the same sediments.

State of China's climate in 2023

China witnessed a warm and dry climate in 2023. The annual surface air temperature reached a new high of 10.71°C, with the hottest autumn and the second hottest summer since 1961. Meanwhile, the annual precipitation was the second lowest since 2012, at 615.0 mm. Precipitation was less than normal from winter to summer, but more in autumn. Consistent with the annual condition, precipitation in the flood season from May to September was also the second lowest since 2012, which was 4.3% less than normal, with the anomalies in the central and eastern parts of China being higher in central areas and lower in the north and south. On the contrary, the West China Autumn Rain brought much more rainfall than normal, with an earlier start and later end. Although there was less annual precipitation in 2023, China suffered seriously from heavy precipitation events and floods. In particular, from the end of July to the beginning of August, a rare, extremely strong rainstorm caused by Typhoon Dussuri hit Beijing, Tianjin, and Hebei, causing an abrupt alteration from drought to flood conditions in North China. By contrast, Southwest China experienced continuous drought from the previous autumn to current spring. In early summer, North China and the Huanghuai region experienced the strongest high-temperature process since 1961. Nevertheless, there were more cold-air processes than normal impacting China, with the most severe of the year occurring in mid-January. Unexpectedly, in spring, there were more sand and dust occurrences in northern China.摘要2023年, 我国气候暖干特征明显, 全国平均气温10.71°C, 为1951年以来最暖; 全国平均降水量615.0 mm, 较常年偏少3.9%, 为2012年以来第二少. 汛期 (5–9月), 全国平均降水量为2012年以来第二少, 中东部降水总体呈“中间多南北少”的分布. 2023年, 我国区域性气象干旱多发, 西南地区遭遇冬春连旱; 春季北方沙尘天气过程偏多; 夏季前期, 华北和黄淮遭受1961年以来最强高温过程; 7月底至8月初, 受台风杜苏芮影响, 京津冀地区发生历史罕见极端强降雨过程, 华北地区出现“旱涝急转”; 华西秋雨开始早, 结束晚, 雨量多.

Projections of the start of the airborne pollen season in Barcelona (NE Iberian Peninsula) over the 21st century

The effects of global warming are numerous and recent studies reveal that they can affect the timing of pollination. Temperature is the meteorological variable that presents a clearer relationship with the start of the pollination season of most of the observed airborne pollen taxa. In Catalonia, in the last fifty years, the average annual air temperature has increased by +0.23 °C/decade, and the local warming has been slightly higher than the one on a global scale. Projections point to an increase in temperature in the coming decades, which would be more marked towards the middle of the century.To analyse the effect of the increase in temperature due to global warming on the starting date of pollen season in Barcelona, a forecasting model has been applied to a set of projected future temperatures estimated by the European RESCCUE project. This model, largely used in the literature, is based on determining the thermal needs of the plant for the pollen season to begin. The model calibration to obtain the initial parameters has been made by using 20 years of pollen data (2000–2019), and the model effectiveness has subsequently been tested through an internal evaluation over the period of the calibration and an external evaluation on 4 years not included in the calibration (2020−2023). The mean bias error in the internal calibration ranged between −0.4 and − 0.6 days, and between +0.5 and − 8.3 in the external one, depending on the taxon. The results of the application of the model to the temperature projections over the 21st century point to a progressive advancement in the pollination dates of several pollen types abundant in the city, allergenic most of them. These advances ranged, at the end of the century, between 15 and 27 days, depending on the climate model, for the scenario of the highest concentrations (RCP8.5) and between 7 and 12 days for the emissions stabilization scenario (RCP4.5).

Relation between soil glycerol dialkyl glycerol tetraethers and temperature in different climatic regions in China

AbstractTemperature variation in the past periods can provide valuable insights into the characteristics and driving mechanisms of current global warming and future changes. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are commonly used to as a temperature proxy to quantitatively reconstruct past temperature changes. However, it still remains unclear whether the relation between brGDGTs and temperature is influenced by other environmental factors, thereby affecting the accuracy of quantitative reconstructions. A comprehensive analysis of the relation between brGDGTs and temperature across various climate regions can greatly enhance the accuracy of reconstructing past temperature changes. Here, we investigate the distribution patterns of soil brGDGTs using 28 new topsoils collected from altitudes ranging from 2100 to 4000 m.a.s.l. in the Hengduan Mountains in the southeastern margin of the Tibetan Plateau (TP), compiled previously published soil brGDGT data in China. Our results reveal distinct distribution patterns of soil brGDGTs between humid and arid regions. Furthermore, we further investigated the correlation between brGDGT indices and various environmental factors from both altitudinal and regional scales. At the altitudinal scale, brGDGT indices exhibit a stronger correlation with mean annual air temperature (MAAT) in alkaline soils (pH &gt; 7) than that in acidic soils (pH &lt; 7). At the regional scale, this correlation is higher in alkaline soils than that in acidic soils as well and is stronger in humid soils (mean annual precipitation [MAP] &gt; 800 mm) than that in semi‐humid and semi‐arid soil (400 &lt; MAP &lt; 800 mm) and arid soil (MAP &lt; 400 mm). In addition, brGDGT‐inferred temperature is more affected by MAP in humid alkaline soils but less affected in humid acidic soils. Therefore, caution is needed to use suitable brGDGT index for palaeotemperature reconstructions in various climate regions.

Distributions of bacterial branched tetraether lipids associated with bacterial communities in hummock and hollow soils from Southern Tibetan peatland

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), special membrane-spanning lipids derived from some bacteria, are widely used as molecular tools in paleoenvironmental studies to reconstruct terrestrial temperature and pH conditions. However, the impact of microtopography discrepancies on the accuracy and applicability of brGDGT-based proxies remains unclear. Here we investigated the distributional patterns of brGDGTs and bacterial communities within the hummock-hollow microtopography in the mid-southern Tibetan peatlands. Our results show that the methylation index of C5-methyl brGDGTs (MBT′5ME) values are significantly correlated with the local mean annual air temperature (MAAT). However, the peat-specific temperature calibration exhibits an underestimation of MAATpeat compared to the present MAAT. We find the MBT′5ME values are significantly lower in the moist hollows than that in the drier hummocks. This discrepancy could be primarily attributed to the shifts in bacterial communities and the physiological adaptation of brGDGT-producing bacteria driven by the high soil water content. These findings highlight the remarkable variability of MBT′5ME values at small spatial scales, which holds profound implications for paleotemperature reconstruction in alpine peatlands.

A climate-driven, altitudinal transition in rock glacier dynamics detected through integration of geomorphological mapping and synthetic aperture radar interferometry (InSAR)-based kinematics

Abstract. In dry southwestern South Tyrol, Italy, rock glaciers are dominant landforms of the high-mountain cryosphere. Their spatial distribution and degree of activity hold critical information on the current state of discontinuous permafrost and consequently on the response potential to climate warming. Traditional geomorphologic mapping, however, owing to the qualitative expert-based nature, typically displays a high degree of uncertainty and variability among operators with respect to the dynamic classification of intact (permafrost-bearing) and relict (permafrost-devoid) rock glaciers. This limits the reliability of geomorphologic rock glacier inventories for basic and applied purposes. To address this limitation, (i) we conduct a systematic evaluation of the improvements that synthetic aperture radar interferometry (InSAR) can afford to the detection and dynamic classification of rock glaciers and (ii) build an integrated inventory that combines the strengths of geomorphologic- and InSAR-based approaches. To exploit fully InSAR-based information towards a better understanding of the topo-climatic conditions that sustain creeping permafrost, we further explore how velocity and the spatial distribution of moving areas (MAs) within rock glaciers may vary as a function of simple topographic variables known to exert first-order controls on incoming solar radiation, such as elevation and aspect. Starting from a geomorphologic inventory (n=789), we characterize the kinematics of InSAR-based MAs and the relevant hosting rock glaciers on 36 Sentinel-1 interferograms in the 2018–2019 period. With respect to the original inventory, InSAR analysis allowed us to identify 14 previously undetected rock glaciers. Further, it confirmed that 246 (76 %) landforms, originally interpreted as intact, do exhibit detectable movement (i.e., ≥1 cm yr−1) and that 270 (60 %) of the relict labeled counterparts do not, whereas 144 (18 %) were kinematically undefined due to decorrelation. Most importantly, InSAR proved critical for reclassifying 121 (15 %) rock glaciers, clarifying that 41 (13 %) of those interpreted as being intact do not exhibit detectable movement and that 80 (17 %) of the original relict ones do move. Reclassification (i) allowed us to identify a cluster of intact rock glaciers below 2000 m a.s.l. associated with positive mean annual air temperature (MAAT), and (ii) by increasing the altitudinal overlap between intact and relict rock glaciers, it depicts a broad transition belt in the aspect–elevation space, which varies from 50 m on west-facing slopes to 500 m on easterly ones. This finding deteriorates the significance of elevation and aspect as topographic proxies for modeling permafrost occurrence and highlights the importance of using InSAR to inform such models. From a process-oriented standpoint, InSAR information proves fundamental for imaging how this altitudinal transition manifests through changing rates and styles of rock glacier surface deformation. Specifically, we find that, as rock glaciers move faster, an increasingly larger proportion of their surface becomes kinematically involved (i.e., percent MA cover) and that this proportion increases with elevation up to 2600–2800 m, beyond which an inflection occurs and consistent average values are attained. Considering that the inflection falls between the −1 and −2 °C MAAT – the lower boundary for discontinuous permafrost – and is independent of slope gradient, we conclude that this altitudinal pattern represents a geomorphic signature: the dynamic expression of increasing permafrost distribution, from sporadic to discontinuous.

Autochthonous grape varieties in the Lower Don Region

This article describes modifi cation changes in the phenotypic traits of grape varieties, including the number of normally developed shoots and infl orescences, the average bunch weight, and grape yield under the infl uence of unstable weather conditions. The research was carried out in the moderate continental climate of the Lower Don region in the period from 2013 to 2022. The average annual air temperature ranged from +10.2 to +11.6 °C, with the climatic norm being +10.4 °C. In the period of active vegetation (May–September), the temperature ranged from +21.2 to +22.7 °C, with the norm being 18.1 °C. The maximum temperature ranged from +37.2 to +40.0 °C, with the norm being +40.0 °C. In winter, during the plant dormancy period (December–February), the average air temperature varied from 0.6 to minus 2.6 °С, with the norm being about minus 2.4 °С. The annual precipitation varied from 292 to 693 mm, with the norm being 548 mm. During the vegetation period of grapes, atmospheric precipitation by the years of observation varied from 99 to 359 mm, with the norm being 177 mm. The aim was to establish the limits of modifi cation variability of phenotypic traits under the infl uence of the unstable moderate continental climate of the Lower Don Region. The research objects were autochthonous grape varieties, including ‘Varyushkin’, ‘Krasnostop’ ‘Zolotovsky’, ‘Kumshatsky Belyi’, ‘Plechistik’, ‘Sibirkovy’, and ‘Tsimlyansky Chernyi’. The reaction norm and modifi cation changes of the phenotypic traits of grape plants under the infl uence of natural conditions in their habitats were studied. The autochthonous grape varieties in contrasting weather conditions exhibited individual and varietal specifi city in terms of reaction norm and adaptability. According to the variability of phenotypic traits and adaptive potential, the varieties were ranked in the following descending order: ‘Plechistik’, ‘Krasnostop Zolotovsky’, ‘Varyushkin’, ‘Kumshatsky Belyi’, ‘Sibirkovy’, and ‘Tsimlyansky Chernyi’. The genotypes ‘Plechistik’, ‘Krasnostop Zolotovsky’, ‘Varyushkin’, and ‘Kumshatsky Belyi’ with their high adaptive potential for formation of stable vine plantations are recommended for developing stable grape plantations in the conditions of the Lower Don region.

Diversity and distribution of chironomids in Central European ponds.

Ponds are common freshwater habitats in the European landscape that substantially contribute to local and regional biodiversity. Chironomids often dominate invertebrate communities in ponds but are usually disregarded in ecological studies due to relatively complicated taxonomy and identification issues. We present a comprehensive overview of the chironomid diversity in 246 ponds spanning a wide range of conditions extending from the Pannonian Plain to the Carpathians. Altogether, we recorded 225 taxa including 192 species from six subfamilies (Podonominae, Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae). However, the chironomid taxa inventory is far from complete and about 16% of the total diversity of pond-dwelling chironomids remains undetected. Chironomid alpha diversity showed a significant unimodal pattern along the elevation gradient with the highest number of taxa per pond expected around 790 m a.s.l. Gamma diversity also peaked in mid-elevations (600-800 m), and the common chironomid taxa partitioned the 2100-m long altitudinal gradient relatively evenly. The heterogeneity of chironomid communities among ponds measured as beta diversity was significantly higher in elevations below 800 m. Temperature and the proportion of surrounding forests significantly influenced alpha diversity of chironomid communities, while urban land cover and pond size had no significant effect. Ponds with a mean annual air temperature of approximately 4.8°C and a low proportion of surrounding forests are expected to harbour the most diverse chironomid communities. Our study showed that chironomids represent a very diverse and often exceptionally rich group of pond-dwelling macroinvertebrates. Given the high diversity and broad range of occupied niches, chironomids should not be overlooked in pond ecology studies. On the contrary, they should be considered a potential model group.

Traces of Local Adaptive Acclimatization Response in the Tracheid Anatomical Traits between Dry and Wet Mesic Norway Spruce (Picea abies) Forests in Moravia, Czech Republic?

Norway spruce (Picea abies) forests in temperate zones are already reacting to short-term extreme summer heatwaves, threatening the vitality of trees and forest productivity, and can even lead to local and regional dieback events. Examining quantitative wood anatomy can provide helpful information in terms of understanding the physiology mechanisms and related responses of conifer trees to local environmental interactions in relation to tracheid adaptive capacity. This study analysed the tracheid functional anatomical traits (FATs) plasticity of six young Norway spruce trees growing in two mesic research plots with high annual precipitation (~43%) and air temperature differences during 2010–2017. The research plots are located in the sub-mountainous (Rájec Němčice) and mountainous (Bílý Kříž) belts of the Moravia region, Czech Republic. Vapour pressure deficit and cell wall reinforcement index (CWRI) were shown to be the most representative environmental parameters as proxies of dry conditions. Tracheid FATs indicated latewood phenological plasticity sensitivity, with more pronounced variability in the warmer and drier plots. Latewood tracheids of Norway spruce trees grown in the RAJ formed significantly thicker cell walls than BK during the studied period. The observed differences between the two research plots indicate additional support for tracheid cells’ hydraulic safety against cavitation and potential traces of adaptive acclimatization response.

Role of climate change on Oriental spruce (Picea orientalis L.): Modeling and mapping

Global climate change is a process with dramatic consequences for ecosystems, and changes that may occur in the potential distribution of plant communities especially draw attention. This study aimed to reveal the potential distribution modeling and mapping of the Oriental spruce (Picea orientalis L.), distributed in a limited area, using current and future (year 2100) climate scenarios in Turkey. The maximum entropy method for potential distribution and Chelsa V2.1 technical specification IPSL-CM6A-LR scenarios (SSP126-SSP370-SSP585) were preferred to reveal the effect of climate change. Results for the current were in the “excellent” category with training and test data AUC 0.981 and 0.977, respectively. The variables contributing to the model were the precipitation amount of the driest month, mean diurnal air temperature range, annual precipitation amount, and mean annual air temperature. Variables contributing to the current model were analysed using the SSP126, SSP370, and SSP585 scenarios of the year 2100. It was assessed that the potential distribution for 2100 decreases according to SSP126, was fragmented according to SSP370, and decreased according to the SSP585 scenario. As a result, the authors determined that the high potential distribution is reduced 61% when the current mapping of Oriental spruce is compared with the SSP585 mapping.

A century-long tendency of change in surface air temperature on the territory of Ukraine

A century-long tendency of change in surface air temperature on the territory of Ukraine

The Effect of the Temperature Increase on Heat Demand Calculation for Building in the Polish Climatology

Heat demand calculation procedures for buildings are currently being conducted based on the Polish Standard grounded on the European Standard for heat losses methodology. Poland was divided into several climatic zones with given calculations and annual average external air temperature values. In each zone, the technical committee gives the temperature that must be considered. The data included in the Polish Standard preparation concern several years backwards. However, throughout the previous years, we have observed the tendency of the temperature to increase throughout the year, not only in Poland. The phenomenon provides scientists with the conclusion that the temperatures will continue to increase yearly. The low temperatures in the winter season will no longer occur. Therefore, it is necessary to analyse the possibility of lowering the heat demand calculation, including the actual prevailing temperature values. The study was conducted regarding possible economic benefits for the building users due to the lower temperature difference between the internal and external temperatures. Three types of heating systems were analysed. The calculations were conducted for air to water heat pump, pellet boiler and gas condensing boiler, proving that regarding the actual meteorological data, the average annual cost reduction will be in the range of 858 PLN to 1,035 PLN.

ГОДОВОЙ СТОК РЕК БАССЕЙНА ОБЫ И СЕВЕРНОГО СКЛОНА ХРЕБТА КАЛБА В УСЛОВИЯХ КЛИМАТИЧЕСКИХ ИЗМЕНЕНИЙ

The patterns of formation of the average annual runoff in the basin of the Oba River and the rivers of the Kalbinsky Range were studied, meteorological characteristics were analyzed - average annual air temperatures and annual precipitation according to weather stations in Eastern Kazakhstan. Trends in changes in hydrometeorological indicators, and primarily the norms of these characteristics in conditions of climate warming, have been identified. The average annual water consumption of various water supplies in the modern period has been calculated. The analysis showed that over the long-term period since 1980, the annual flow of the rivers in question has decreased in the river basin. Both are 10.6% and 2.7% of the left bank tributaries of the Ertis. It should be noted that the emerging trend of increasing annual precipitation and average annual water flows of the rivers on the left bank of the Ertis since the beginning of 2010 may subsequently become stable, and in the future should lead to an increase in precipitation in the territory and the flow of the right-bank tributaries of the Ertis.

Greenness, air pollution, and temperature exposure effects in predicting premature mortality and morbidity: A small-area study using spatial random forest model

BackgroundAlthough studies have provided negative impacts of air pollution, heat or cold exposure on mortality and morbidity, and positive effects of increased greenness on reducing them, a few studies have focused on exploring combined and synergetic effects of these exposures in predicting these health outcomes, and most had ignored the spatial autocorrelation in analyzing their health effects. This study aims to investigate the health effects of air pollution, greenness, and temperature exposure on premature mortality and morbidity within a spatial machine-learning modeling framework. MethodsYears of potential life lost reflecting premature mortality and comparative illness and disability ratio reflecting chronic morbidity from 1673 small areas covering Greater Manchester for the year 2008–2013 obtained. Average annual levels of NO2 concentration, normalized difference vegetation index (NDVI) representing greenness, and annual average air temperature were utilized to assess exposure in each area. These exposures were linked to health outcomes using non-spatial and spatial random forest (RF) models while accounting for spatial autocorrelation. ResultsSpatial-RF models provided the best predictive accuracy when accounted for spatial autocorrelation. Among the exposures considered, air pollution emerged as the most influential in predicting mortality and morbidity, followed by NDVI and temperature exposure. Nonlinear exposure-response relations were observed, and interactions between exposures illustrated specific ranges or sweet and sour spots of exposure thresholds where combined effects either exacerbate or moderate health conditions. ConclusionAir pollution exposure had a greater negative impact on health compared to greenness and temperature exposure. Combined exposure effects may indicate the highest influence of premature mortality and morbidity burden.

Climate‐Driven Increases in Stream Metal Concentrations in Mineralized Watersheds Throughout the Colorado Rocky Mountains, USA

AbstractIncreasing stream metal concentrations apparently caused by climate warming have been reported for a small number of mountain watersheds containing hydrothermally altered bedrock with abundant sulfide minerals (mineralized watersheds). Such increases are concerning and could negatively impact downstream ecosystem health, water resources, and mine‐site remediation efforts. However, the pervasiveness and typical magnitude of these trends remain uncertain. We aggregated available streamwater chemistry data collected from late summer and fall over the past 40 years for 22 mineralized watersheds throughout the Colorado Rocky Mountains. Temporal trend analysis performed using the Regional Kendall Test indicates significant regional upward trends of ∼2% of the site median per year for sulfate, zinc, and copper concentrations in the 17 streams affected by acid rock drainage (ARD; median pH ≤ 5.5), equivalent to concentrations roughly doubling over the past 30 years. An examination of potential load trends utilizing streamflow data from eight “index gages” located near the sample sites provides strong support for regionally increasing sulfate and metal loads in ARD‐affected streams, particularly at higher elevations. Declining streamflows are likely contributing to regionally increasing concentrations, but increasing loads appear to be on average an equal or greater contributor. Comparison of selected site characteristics with site concentration trend magnitudes shows the highest correlation for mean annual air temperature and mean elevation (R2 of 0.42 and 0.35, respectively, with all others being ≤0.14). Future research on climate‐driven controlling mechanisms should therefore focus on processes such as melting of frozen ground directly linked to site mean temperature and elevation.

Impact of permafrost degradation on the extreme increase of dissolved iron concentration in the Amur river during 1995–1997

Primary production in the Sea of Okhotsk is largely supported by dissolved iron (dFe) transported by the Amur river, indicating the importance of dFe discharge from terrestrial environments. However, little is known about the mechanisms of dFe discharge into the Amur river, especially in terms of long-term change in dFe concentration. In the Amur river, extreme increase in dFe concentration was observed between 1995 and 1997, the cause of which remains unclear. As a cause of this iron anomaly, we considered the impact of permafrost degradation. To link the permafrost degradation to long-term variation in dFe concentration, we examined the changes in annual air temperature (Ta), accumulated temperature (AT), and net precipitation for three regions (northeast, south, and northwest) of the basin between 1960 and 2006. Ta and AT were relatively high in one out of every few years, and were especially high during 1988–1990 continuously. Net precipitation in late summer (July to September) has increased since 1977 and has stayed positive until 2006 throughout the basin. Most importantly, we found significant correlations between Ta and late summer dFe concentration with a 7-year lag (r = 0.54–0.69, p < 0.01), which indicate a close relationship between high Ta in year Y and increased late summer dFe concentration in year Y + 7. This correlation was the strongest in northeastern Amur basin where permafrost coverage is the highest. Similar 7-year lag correlation was also found between AT in the northeastern basin and late summer dFe concentration (r = 0.51, p < 0.01). Based on our findings, we propose the following hypothesis as a cause of iron anomaly. (1) Increased net precipitation since 1977 has increased soil moisture, which created suitable conditions for microbial dFe generation; (2) permafrost degradation during the warm years of 1988–1990 promoted iron bioavailability and led to the intensive dFe generation in the deeper part of the active layer; and (3) dFe took approximately 7 years to reach the rivers and extremely increased dFe concentration during 1995–1997. This is the first study to suggest the time-lagged impact of permafrost degradation on iron biogeochemistry in the Amur river basin.

Long-term changes in qualitative composition of the Buzuluk Pine Forest avifauna (Orenburg Province area) based on retrospective and present-time observations

We conducted a comparative analysis of qualitative composition of the Buzuluk Pine Forest avifauna, mainly based on data collected by ornithologist E.P. Knorre for the period 1928–1941, and modern observations done between 2000 and the present. Retrospective data were obtained from the now-defunct Buzuluk Bor Reserve with an area of 10 503 hectares (now Borovoye-Opytnoe Forestry in the Orenburg Province). Present-time personal avifaunistic observations (using standard methods with referring to literature sources) were carried out on an area of 49 000 hectares, both in Borovoye-Opytnoe and in several adjacent forestries that were part of the Buzuluk Bor National Park within the Orenburg Province. Comparing the historical and current bird lists, we used a relative assessment of changes in the composition of various bird groups based on the observed and expected frequencies according to the χ2 test. Long-term data on average annual temperatures and precipitation from a nearby state weather station were also used. As a result, it is shown that by now the list of birds of E.P. Knorre decreased from 153 to 109 species (28.8%). When comparing by orders, the water birds were found to be the most affected group. The number of species in orders Podicipediformes, Ciconiiformes, Gruiformes decreased by 80–100%, and it dropped by more than 50% in orders Anseriformes and Charadriiformes. There was also a slightly smaller decrease in the number of species in orders Falconiformes and Strigiformes – by about 40%. An assessment of the relative changes in various bird groups from Knorre’s list based on expected and observed frequencies showed significant differences in the portion of avifauna associated with water. It decreased between 23.5% and 9% in the group ‘Limnophiles’ (χ2 = 11.7, df = 1, p = 0.0006) and between 24.8% and 9% in the group of orders represented by waterfowl and waterbird species (χ2 = 13.4, df = 1, p = 0.0002). The change in the portion of birds of prey was statistically non-significant. The same portion assessment method did not statistically confirm the decrease in the rest ecological and order groups. Comparison of groups by occurrence status found no significant changes in the portions of all groups of birds in the past and present, but the largest reduction was recorded in the group of migrating species. The portion of migrants decreased from 8.7% to 3.0% (χ2 = 3.2, df = 1, p = 0.07, Yates corrected χ2 = 2.2, p = 0.1). A dramatic decline in group of bird species associated with wetlands was suggested to be due, among other factors, to the progressive desiccation of the Buzuluk Pine Forest, as E. Knorre himself wrote in his report. The ongoing aridization of the climate, as shown by the graph of average annual air temperatures, has been taking place since at least the 20s of the twentieth century and led to the drying-up of wetlands, and also to migration of groundwater to deeper horizons. The emerging trend towards a reduction in the portion of migrants could be explained by the fact that a number of migratory bird species, mainly ducks and waders, disappeared in the study area, and several other migrants began breeding species. In addition, large-scale fires and logging led to formation of burned wasteland areas inside the forest at the beginning of the twentieth century and also probably contributed to fragmentation and desiccation of this biome.

Modeling the Link Between Air Convection and the Occurrence of Short‐Term Permafrost in a Low‐Altitude Cold Talus Slope

ABSTRACTWe extend a numerical modeling approach developed to explicitly model convective heat transfer in periglacial landforms to represent the ground thermal regime of low‐altitude talus slopes. Our model solves for heat conduction and accounts explicitly for air convection adopting a Darcy term with a Boussinesq approximation for air circulation in the porous ground. Numerical model experiments for the low‐altitude talus slope Dreveneuse, Switzerland, confirm that air convection is the key to forming and maintaining ground ice. In the model, the porous talus slope is underlain by a layer of water‐bearing morainic material. In years, where the gradient between air and talus temperature is sufficiently large to result in increased convection and therefore cooling, ground ice forms due to air convection within the porous material and lasts for more than a year. It is only by considering convection that the model is able to represent the occurrences of ground ice, in accordance with temperature observations on‐site. These findings are important, as they confirm that ground ice can be formed and maintained in landforms with a mean annual air temperature &gt; 0°C if ground air convection is present combined with the presence of water.

Change and influence of agroclimatic conditions on oat yield in Yakutia

The results of the dynamics analysis of multi-year meteorological indicators and study of their influence on the yield of the released oat varieties in different agroclimatic zones of Yakutia are presented. It is shown that in the period from 1960 to 2021 the mean annual air temperature in Central Yakutia (Pokrovsk meteorological station) increased annually by 0.045 °C, from 1999 to 2021 – by 0.088 °C, the number of dry years in June increased from 67 to 92% due to a 21% increase in years with medium (HTC = 0.41-0.60) and very strong (HTC &lt; 0.21) drought. In July, drought was recorded in 50% of the years, in August – in 38%. In all agroclimatic zones in the period from 2014 to 2021 for June – August the average daily air temperature annually increased by 0.16...0.34 °С and their sum by 14...28 °С, with precipitation decreasing by 3-16 mm and HTC value by 0.04-0.12 units. Climate change from 2014 to 2021 was 3 to 8 times more intense than from 1999 to 2022. There was a strong variability of yields of the released oat varieties in each agroclimatic zone: Central – from 0.38 to 2.14 t/ha (V = 60–73%), Zarechnaya – from 0.31 to 3.55 t/ha (V = 41–49%), Srednelenskaya – from 1.51 to 4.66 t/ha (V = 30–36%). The greatest annual decrease in grain yield of oat varieties (by 0.25–0.26 t/ha) was observed in arid agroclimatic zones – Central (Yakutsk SCTS) and Zarechnaya (Megino-Kangalassky SCTS) – compared to the wetter Srednelenskaya zone (Olyokminsky SCTS – by 0.10 t/ha). More significant influence on the yield in the Central and Zarechnaya zones was made by precipitation and HTC of the growing season (r = 0.77...0.84), in the Srednelenskaya zone – by temperature (r = – 0.79). Negative effect of temperature on the yield in the Central zone was observed in June (r = – 0.83), Zarechnaya zone - in July (r = – 0.83), in the Srednelenskaya zone – in August (r = –0.86). Precipitation and HTC had the greatest influence on the yield in the Central zone in June and July (r = 0.56...0.59), Zarechnaya zone – July and August (r = 0.60...0.76). In the Srednelenskaya zone the relationship of the yield with precipitation and HTC in June and July was positive (r = 0.23...0.37), in August – negative (r = – 0.57...– 0.71). Significant variability in grain yields of the released oat varieties indicates the variability of weather conditions and the need to cultivate oat varieties that provide a more stable yield in different agroclimatic zones of Yakutia.