Cold Years Research Articles

Monitoring of Pinus sylvestris L. and P. nigra Arn. from Maleshevska Mountain Using Dendrochronology and Climatic Data

The conducted analysis is related to the stress periods, the functional type of trees, as well as climatic types of years and climatic patterns identification to obtain the existing risk for the forest stands. Thirty-nine Scots pine trees and ninety-six black pine trees were sampled from the Sokolata reserve and the area near the village of Igralishte in Maleshevska Mountain, Southwest Bulgaria (longitude 23.1–23.13; latitude 41.5–41.6 and altitude 860–950 m). The obtained common stress years for Scots pine were 1980, 1991, 1993, 1994, 2004, 2007, 2012, and for the black pine – 1988, 1996, 2003, 2012, 2013, 2015. The received average functional types for Scots pine were, respectively, trees with very rare eustress occurrence, very short duration, and normal or deep amplitude. There is some risk for the trees from Igralishte village due to the available deep eustress. The obtained average functional types for the black pine were, respectively, trees with very rare eustress occurrence, very short duration and very small depth or very deep amplitude – A1 and A5. There is à risk for the black pine trees from Igralishte village due to the available very deep eustress. For Scots pine, two consecutive cold years and a third cold and wet one, as well as three consecutive cold and wet years, led to the onset of eustress. Other critical situations included the alternation of cold and wet years with warm and wet ones and vice versa, or the alternation of warm and dry two-year periods with a cold and wet climate. For the black pine consecutive dry years exert a stressful influence, as well as the alternation from dry to wet and warm years. Cold years and cold and wet years had a critical influence.

Relationship between temperature and relative humidity with CO2 and CH4 concentration and ectoparasite abundance in blue tit (Cyanistes caeruleus) nests.

The presence of nestlings influences the microclimate inside avian nesting cavities. We explored the relationship between temperature and relative humidity and the abundance of ectoparasites and gas concentrations in blue tit nest boxes during the nestling period by comparing two years with differing climatic conditions. In the second year, we also manipulated the temperature and humidity inside the nest boxes. The average temperature in nest boxes was colder during 2016 than 2017; in the latter, even warmer conditions were attained due to the experimental manipulation of temperature. Carbon dioxide (CO2) concentration in the forest air was slightly lower in 2016 than 2017. However, in both years, the CO2 concentration of nest box air was higher than that of forest air, with 2017 showing a greater difference. Differences in brood size, larger in 2016, did not explain the difference in CO2 concentration. However, CO2 concentration was higher in nestboxes in the warmer year implying that at higher temperatures, organic matter decomposition likely accelerates, releasing more CO2 into the atmosphere. By contrast, CH4 concentration in nest-box air, which was similar in both years, was lower than that in forest air, particularly in the wettest and coldest year. Different relationships were found between the abundance of different ectoparasites and the temperature, relative humidity, and gas concentration measured at different days of nestling age. For example, a positive association is observed between flea larval abundance and temperature at nestling day 8, but a negative one is observed for mites under the same microclimate conditions. Moreover, a negative relationship was observed between the abundance of mites, midges, and blackflies and CH4 concentration at different nestling ages. These results suggest that changes in climatic conditions can also affect the concentrations of CH4 and CO2 inside and outside nest boxes, which in turn differentially affect ectoparasite abundance.

Reconstruction of Minimum May Temperatures in Northeast China Since 1797 AD Based on Tree Ring Width in Pinus sylvestris var. mongolica

We developed a tree ring width chronology from 1797 to 2020 (224 years) for the northwestern foothills of the Greater Khingan Mountains (GKMs) in northeastern China using 51 tree ring sample cores from 24 Pinus sylvestris var. mongolica (PSM). Pearson’s correlation analysis was used to analyze the relationship between tree ring width and regional climate factors. The standardized chronology was positively associated with the minimum temperature (Tmin) in the previous May (r = 0.721, p < 0.01), indicating that this parameter was the main climatic factor limiting PSM growth in the region. We established a secure reconstruction equation for the May Tmin from 1797 to 2020. There were 31 warm and 43 cold years in the 224-year reconstructed temperature series, accounting for 13.8% and 19.2% of the total years, respectively. Warm periods were observed in 1820–1829, 1877–1898, 1947–1958, and 1991–2020, whereas cold periods occurred in 1820, 1829–1870, 1899–1927, 1934–1947, and 1960–1988. The observed temperature sequence was highly consistent with the reconstructed sequence from the tree rings, which verified the reliability of the reconstructed results. The spatial correlation analysis indicated that the reconstructed temperature sequence accurately represented the temperature changes in the northwestern foothills of the GKM and surrounding areas. Multi-window spectral analysis and wavelet analysis revealed significant periodic fluctuations from 2 to 6 years, 21.2 years, 48.5 years, and 102.2 years. These periodic variations may be related to the El Niño–Southern Oscillation (ENSO), the Atlantic Multi-Year Intergenerational Oscillation (AMO), the Pacific Decadal Oscillation (PDO), and solar activity. This study expands the existing climate records in the region and provides valuable data support for understanding climate change patterns in the GKM and the scientific predictions of future climate changes.

Tree-ring maximum latewood density reveals unprecedented warming and long-term summer temperature in the upper Indus Basin, northern Pakistan

Understanding long-term temperature variability in the Upper Indus Basin (UIB), northern Pakistan, and its driving mechanisms is challenging due to the scarcity of long observational records and available literature. In this study, we reconstructed a 651-year (1370–2020 CE) warm-season (March–September) temperature record using the tree-ring maximum latewood density (MXD) of blue pine (Pinus wallichiana). The reconstruction explains 57 % of the variance in actual temperature during the common calibration period (1972–2020 CE). Our analysis identified ten high-temperature periods (temperature > 20.9 °C) and nineteen low-temperature periods (temperature < 19.8 °C), with the coldest years being 1392, 1707, 1817, and 1837, and the warmest years being 2013, 2016, 2017, and 2018. Spatial correlation analysis reveals a significant positive correlation with field temperature, predominantly in neighboring regions, and a significant negative correlation with relative humidity and precipitation. Multi-taper spectral analysis shows inter-annual (1.9, 2.5, 2.7, 5.5 years) and interdecadal (11, 18, 23, 25, 40, 71 years) cycles, suggesting a potential linkage with the Atlantic Multidecadal Oscillation (AMO). The negative linkage between our reconstruction and the region's standardized Palmer Drought Severity Index (scPDSI) indicates that continued temperature increase could result in severe drought in northern Pakistan in the near future. During the 20th century, the UIB experienced two distinct warming phases: 1948–1970 CE and 1994–2020 CE. The warming rate during 1994–2020 CE was 0.5 °C higher, indicating unprecedented recent warming. The reconstructed temperature record also demonstrates a large-scale spatiotemporal signal and a strong connection with most recorded volcanic eruptions. These findings enhance our understanding of long-term temperature variability in the region, highlighting the significance of MXD in reconstructing past temperature patterns.

Long-term climate-based sizing and economic assessment of air-water heat pumps for residential heating

This study presents a novel methodology for sizing air–water heat pumps (ASHP) for space heating and hot water supply in buildings. Utilizing long-term local climatic data, the developed tool determines the coefficient of performance (COP) and feasibility of ASHP. The sizing algorithm incorporates peak heat demand, unitary final energy demand, and seasonal heat demand across various detached house sizes. Annual local heating system operation time and key economic indicators are derived for each case across 3 European countries. A new approach is precise investigation of 10-year outdoor temperatures and apply it to heat pump (HP) modeling, which enabled a distinction between so-called warm and cold years. The results underscore substantial variations in net present value (NPV) between warm and cold years, illustrating the critical influence of precise climate data on the performance of HPs. The study revealed that for a 160 m2 house in Poland, annual electricity consumption by HPs ranged from 3736 kWh during warm years to 12,908 kWh during cold years, showing a significant variation in performance based on climate conditions. The comprehensive tool allows for precise adjustments of heating systems to actual local climate conditions, improving both economic and environmental outcomes. This comparative assessment aids in the optimal selection of HPs, ensuring energy efficiency and sustainability in residential heating systems. Building on studies from various climatic regions, this work addresses the knowledge gap in performance and explores the feasibility of HP in a changing climate using precise modeling techniques.

Interannual and seasonal variability of the air–sea CO2 exchange at Utö in the coastal region of the Baltic Sea

Abstract. Oceans alleviate the accumulation of atmospheric CO2 by absorbing approximately a quarter of all anthropogenic emissions. In the deep oceans, carbon uptake is dominated by aquatic phase chemistry, whereas in biologically active coastal seas the marine ecosystem and biogeochemistry play an important role in the carbon uptake. Coastal seas are hotspots of organic and inorganic matter transport between the land and the oceans, and thus they are important for the marine carbon cycling. In this study, we investigate the net air–sea CO2 exchange at the Utö Atmospheric and Marine Research Station, located at the southern edge of the Archipelago Sea within the Baltic Sea, using the data collected during 2017–2021. The air–sea fluxes of CO2 were measured using the eddy covariance technique, supported by the flux parameterization based on the pCO2 and wind speed measurements. During the spring–summer months (April–August), the sea was gaining carbon dioxide from the atmosphere, with the highest monthly sink fluxes typically occurring in May, being −0.26 µmol m−2 s−1 on average. The sea was releasing the CO2 to the atmosphere in September–March, and the highest source fluxes were typically observed in September, being 0.42 µmol m−2 s−1 on average. On an annual basis, the study region was found to be a net source of atmospheric CO2, and on average, the annual net exchange was 27.1 gC m−1 yr−1, which is comparable to the exchange observed in the Gulf of Bothnia, the Baltic Sea. The annual net air–sea CO2 exchanges varied between 18.2 (2018) and 39.1 gC m−1 yr−1 (2017). During the coldest year, 2017, the spring–summer sink fluxes remained low compared to the other years, as a result of relatively high seawater pCO2 in summer, which never fell below 220 µatm during that year. The spring–summer phytoplankton blooms of 2017 were weak, possibly due to the cloudy summer and deeply mixed surface layer, which restrained the photosynthetic fixation of dissolved inorganic carbon in the surface waters. The algal blooms in spring–summer 2018 and the consequent pCO2 drawdown were strong, fueled by high pre-spring nutrient concentrations. The systematic positive annual CO2 balances suggest that our coastal study site is affected by carbon flows originating from elsewhere, possibly as organic carbon, which is remineralized and released to the atmosphere as CO2. This coastal source of CO2 fueled by the organic matter originating probably from land ecosystems stresses the importance of understanding the carbon cycling in the land–sea continuum.

The weather of 1740, the coldest year in central Europe in 600 years

Abstract. The winter of 1739/40 is known as one of the coldest winters in Europe since early instrumental measurements began. Many contemporary sources discuss the cold waves and compare the winter to that of 1708/09. It is less well known that the year 1740 remained cold until August and was again cold in October and that negative temperature anomalies were also found over Eurasia and North America. The 1739/40 cold season over northern mid-latitude land areas was perhaps the coldest in 300 years, and 1740 was the coldest year in central Europe in 600 years. New monthly global climate reconstructions allow us to address this momentous event in greater detail, while daily observations and weather reconstructions give insight into the synoptic situations. Over Europe, we find that the event was initiated by a strong Scandinavian blocking in early January, allowing the advection of continental cold air. From February until June, high pressure dominated over Ireland, arguably associated with frequent eastern Atlantic blocking. This led to cold-air advection from the cold northern North Atlantic. During the summer, cyclonic weather dominated over central Europe, associated with cold and wet air from the Atlantic. The possible role of oceanic influences (El Niño) and external forcings (eruption of Mount Tarumae in 1739) are discussed. While a possible El Niño event might have contributed to the winter cold spells, the eastern Atlantic blocking is arguably unrelated to either El Niño or the volcanic eruption. All in all, the cold year of 1740 marks one of the strongest, arguably unforced excursions in European temperature.

Warming events and their causes at the Bering Sea section B in summer of 1999–2019

Based on hydrological data for the Bering Sea from 1999 to 2019 during the Chinese National Arctic Research Expeditions (CHINAREs), along with oceanographic and meteorological data from the National Centers for Environmental Information (NCEI) and the European Centre for Medium-Range Weather Forecasts (ECMWF), we investigated trends in summer at the Bering Sea section B over the past 20 years and their underlying causes. The results revealed a pronounced rise in temperature at the Bering Sea section B in 2003, 2014, 2016, 2018, and 2019, suggesting a shift towards a new phase of warmth starting in 2014. In warm years (2003, 2014, 2016, 2018, and 2019), the mean maximum temperature in the upper layer in the basin north of 57°N and on the continental shelf were roughly 2.7 °C, 2.6 °C higher than that in cold years (1999, 2008, 2010, and 2012). Additionally, the mean minimum temperature of the cold water in the middle layer in the basin was roughly 0.7 °C higher in the warm years compared to the cold years. This difference between the warm and cold years was evident in the heat content: the average heat content in the upper to middle layers in the basin north of 57°N and on the continental shelf were about 1.2 and 0.9 GJ/m2 higher, respectively, in the warm years than the cold years. However, there was a modest warming trend in the basin south of 57°N, and the temperature in the mid-layer on the continental shelf showed year-to-year stability, in contrast to the significant warming observed elsewhere. Further study suggested that temperature fluctuation in the basin was closely tied to seasonal 2-m air temperature. In addition, the southern basin, divided at 57°N, experienced larger positive or negative anomalous wind stress curl compared to the northern basin. This discrepancy resulted in differing causes of temperature variation between the two regions. Temperature change in the upper layer on the continental shelf was attributed to an increase in cumulative net heat flux resulting from reduced sea ice, while the temperature in the middle layer on the continental shelf was limited by the enhanced density gradient between the upper and middle layer caused by melt ice, preventing significant warming. Overall, the thermal state for the Bering Sea section B was influenced by a combination of factors, including net heat flux, sea ice, and atmospheric conditions, contributing to the year-to-year variation characterized by alternating cold and warm regimes.

Food system adaptation and maintaining trade could mitigate global famine in abrupt sunlight reduction scenarios

After a major nuclear war, volcanic eruption or asteroid or comet impact that causes an abrupt sunlight reduction scenario, agricultural yields would plummet. We analyzed a nuclear winter scenario involving the injection of 150 Tg of soot in the stratosphere using a linear optimization model with and without global food trade. We investigated the effects of loss of global food trade, some simple adaptations like rationing and storage of excess food for the coldest years, and rapid, large-scale deployment of food sources which are less dependent on present day climate (so called resilient foods) including cool tolerant crops, methane single cell protein, lignocellulosic sugar, greenhouse crops, and seaweed. In the worst case of no global food trade and no adaptations, the model predicts a global famine. However, scaling up resilient foods quickly could mitigate this for many countries. Maintaining global food trade would further alleviate pressure on local food systems, unlocking the potential to feed the entire global population. However, insufficient preparation, post-disaster conflict, or economic collapse would worsen outcomes and hinder adaptation.

Assessing Past and Future Heat and Cold Waves over Iraq Using CMIP6 Model

The United Nations classified Iraq as one of the most vulnerable countries to climate change. Temperatures continue to rise leading to more heat waves, droughts, sandstorms, and desertification. This study aims to investigate the characteristics of heat waves over Iraq from 1982 to 2050 using CMIP6 model at RCP4.5 scenarios. The results clearly showed that the effects of climatic changes were evident in the maximum and minimum temperatures inside Iraq. Average temperature increased of 1.9°C between 1982 and 2020. During 1999, there was a sharp increase in summer days for all stations. The annual number of summer days for the stations (Basra, Nasiriyah, Baghdad, Rutba, Sulaymaniyah, and Mosul) was (195, 193, 177, 108, 106, and 142), while in 2039 the number of summer days was found to be (212, 206, 194, 143, 144, and 149), respectively. The increase in the number of discrete heat wave events began in 2020 and will continue until 2050 for almost the entire territory of Iraq. The warmest day in Basra was in July 2016 with 53.2°C, while the projection of the warmest day was found in July 2046 with 55.7°C. The coldest daily temperature reached -5.03 °C for Baghdad in 1997 and -10.1°C for Sulaymaniyah in 1985, while the projection of the coldest day was -16.2°C over Sulaymaniyah in 2039. The trend of the number of days contributing to cold wave events was decreasing for all stations whereas the coldest year for all stations was 1992 for the entire period (1982 to 2020). Heat waves accelerated from the beginning of the study period in 1982 and continued to increase until the end of the study in 2050 in Iraq.

Different climate conditions drive variations in gross primary productivity and woody biomass accumulation in a temperate and a boreal conifer forest in Canada

Understanding the complex relationships between climate, forest carbon (C) uptake and biomass growth has become a research priority, crucial for assessing the climate change impacts on forest C sequestration. Such associations are expected to vary across biomes, due to different climate constraints on tree physiology. However, our understanding of the seasonal dynamics of long-term C sequestration and how climate influences them in different forest biomes is still limited.We investigated a boreal Pinus banksiana forest (Old Jack Pine, OJP) and a temperate Pinus strobus plantation (Turkey Point, TP39) in Canada. We aimed to assess the link between C uptake and above-ground woody biomass growth, and the effects of climate inter-annual variability on them. We used daily records of climate and gross primary productivity (GPP, period 1999–2019 at OJP and 2003–2018 at TP39), and investigated xylem biomass proxies at cell (cell wall area) and tree-ring level (ring wall area) from 1970 to 2019 at OJP, and from 1970 to 2018 at TP39.In both forests, the direct link between C sink and C source was revealed by the common inter-annual variability of GPP and xylem biomass. GPP and xylem biomass were mostly influenced by spring and late summer temperature at OJP. However, at both sites, summer drought negatively influenced GPP, and biomass growth especially in recent decades. Analysis of dry and cold years evidenced short-term negative effects of low temperature on GPP and xylem biomass in OJP, and of drought in TP39.Long-term intra-annual analyses are crucial to assess the variable effects of climate on forest C cycle. Warm spring and autumn can benefit both GPP and biomass growth, but even in the boreal forest, summer drought has negative impacts. Increasing dry spells, especially in the temperate site, could reduce future forest capacity to uptake C and fix it in wood biomass.

The impact of vertical mixing on the variability of salinity in the Black Sea pycnocline: Role of winter convection, vertical shear and mediterranean waters injections.

Rapid rise of salinity is observed in the Black Sea in recent years, with the largest positive trend (0.07 psμ per 10 years) detected in the pycnocline. We use long-term hydrological measurements for 1985–2019 to show that salinity of pycnocline has intense seasonal and interannual variability modulated by the mechanical and convective mixing. In the warm period of a year, shear turbulence driven by strong winds and intense geostrophic currents causes the penetration of warm waters into the lower density layers. This is accompanied by the rise in their salinity, the source of which is the deep saline waters situated below the halocline. This process is most intense in the areas of downwelling and intensifies in the autumn period, when thermal stratification is relatively weak. Another important reason is the entrainment of salty Mediterranean waters in the upper part of the Black Sea halocline, which is modulated by the deepening of the seasonal thermocline near the Bosphorus strait and mechanical mixing.The increase of salinity is compensated during cold winters, when convective mixing transports fresher water influenced by river discharge into lower density layers of the basin and causes a decrease in pycnocline salinity. This process is most intense in the center of the cyclonic gyres, where pycnocline is located closer to the surface and winter temperature reaches minimal values.Due to the long-term warming of the Black Sea, the process of freshening of deep layers now is observed only in rare cold years. At the same time, an intensification of wind speed, vorticity, and geostrophic circulation processes promote the blurring of the halocline and the rise of the salinity of the Black Sea upper layers. Such rise begins after 2007 in the upper part of Black Sea halocline (depth 50–100 m) and is traced down to 250 m by 2020.

Modeling the larval growth and survival of Pacific cod (Gadus macrocephalus) in the eastern Bering Sea

The eastern Bering Sea (EBS) is a highly productive ecosystem that supports several important commercial species such as the Pacific cod (Gadus macrocephalus). Climate variability affects the population dynamics of this stock throughout its life stages, especially early life stages, since they are particularly susceptible to environmental changes. In recent decades, warm and cold stanzas (i.e., 3–5 year periods) have been observed in the EBS, and there is evidence that they can modulate the recruitment of this stock, causing important socioeconomic impacts. Using a mechanistic individual-based model, this study investigates the spatial and temporal variability of growth and survival of Pacific cod's early life stages during 2000–2020. We examined changes by year and over space and compared our results with published literature to validate our model. We found that temperature played a key role in modulating the survival of fish larvae, observing an increase in starvation events in warmer years or locations. Periods or areas with low prey density, especially small-bodied copepods, also contributed to increased starvation. The average temperature in the fish habitat was negatively correlated with recruitment estimates from the stock assessment model. Growth was primarily temperature-driven; however, food-limited growth became more frequent when larvae were smaller during cold years. Spatially, we found that the environmental conditions in the southeastern Bering Sea may favor larval survival but reduce growth, and higher mortality may be persistent on the middle and outer shelf. Our model produces results that agree with previous field studies, and it offers a valuable tool to investigate other ecological questions on the impact of the environment on early life stages of fishes.

Preconditioning of mountain permafrost towards degradation detected by electrical resistivity

Warming permafrost has been detected worldwide and is projected to continue during the next century by many modelling studies. In mountain regions, this can lead to potentially hazardous impacts on short time-scales by an increased tendency for slope instabilities. However, time scales of permafrost thaw and the role of the ice content are less clear, especially in heterogeneous mountain terrain, where ice content can vary between zero and supersaturated conditions over small distances. Warming of permafrost near the freezing point shows therefore complex inter-annual behaviour due to latent heat effects during thawing and the influence of the snow-cover, which is governed by highly non-linear processes itself. Here, we demonstrate a preconditioning effect within near-surface layers in mountain permafrost that causes non-linear degradation and accelerates thaw. We hypothesise that a summer heat wave, as has occurred in the Central European summers 2003, 2015 and 2022, will enhance permafrost degradation if the active layer and the top of the permafrost layer are already preconditioned, i.e. have reduced latent heat content. This preconditioning can already be effectuated by a singular warm year, leading to exceptionally strong melting of the ground ice. On sloping terrain this ice-loss can be considered as irreversible, as large parts of the melted water will drain during the process, and an equivalent build-up of ice in cold years does not happen on similar time-scales as the melting. We propose a simple geophysical approach based on electrical resistivity tomography surveys that can assess the state of preconditioning in the absence of boreholes. In addition, we will show that resistivity data from a total of 124 permafrost sites in the Andes, Europe, and Antarctic adhere to a distinct power law behaviour between unfrozen and frozen states, which confirms the consistent electrical behaviour of permafrost and active layer materials over a wide range of landforms and material composition.

Source, preservation and re-suspension of 239,240Pu in a well dated peat core collected from northwest China

Owning to the high radiotoxicity in high concentrations, as well as the irreplaceability in quantifying soil erosion rates, demarcating the Anthropocene, and dating of sediment, anthropogenic 239,240Pu have drawn high attention. However, the source in specific areas, preservation characteristics in different environment media, and re-distribution process after the cessation of atmospheric nuclear weapons tests, have not been fully understood, which obscures the exact start year, temporal variation, and deposition flux of 239,240Pu in sedimentary records, and hinders the wide application of 239,240Pu in environment study. A sediment core from the Yiwu peat bog with dominance of atmospheric deposition in the source material, simple sedimentary environment, and high dust deposition flux, was collected to examine the 239,240Pu, and explore the source, preservation, and re-distribution process. The double peaks of 239,240Pu in 1952 CE and 1963 CE, as well as 240Pu/239Pu ratios of 0.163–0.190 with an average of 0.177 ± 0.010 confirmed that the 239,240Pu source originated predominantly from global fallout. The minimal vertical migration of plutonium in the Yiwu peat core was attributed to the near-neutral pH condition. The high inventory of 128 ± 7 Bq m−2, as well as the atypical negative correlation between 239,240Pu concentrations and organic matter content (r = − 0.79, P < 0.01), was attributed to the contribution of 239,240Pu re-suspended with dust from the neighboring Gobi Desert, particularly in the cold and dry years. The total re-suspended 239,240Pu was estimated to be 77 Bq m−2, exceeding the direct fallout level of 51 Bq m−2 during 1945–2016 CE. In this study, the specified deposition pattern of 239,240Pu after the cessation of atmospheric nuclear weapons was established, providing an important standard for multiple environmental studies, and the re-suspended amount of 239,240Pu in a typical arid area was quantified for the first time.

Features of phytoplankton changes in the Sevastopol and Karadag coastal areas (the Black sea) in spring

Based on field-monitoring and satellite dataset obtained during spring season, we studied the features of phytoplankton changes under effect of hydrometeorological factors in the coastal areas of Sevastopol in 2000–2021 and Karadag in 1989–2021. For these areas, significant positive correlations were observed between phytoplankton biomass and winds causing coastal upwellings which lift nutrients from deep layers to the surface. On the basis of Principal Component Analysis (PCA) and ANOVA, a positive effect of the north wind speed on phytoplankton biomass in the Sevastopol and Karadag coastal areas was established. Different mechanisms of the north wind effect on the nutrient-rich waters rise for two investigated areas were revealed and it was due to peculiarities of these coastal areas. The north wind also contributes to nutrient supply from the river runoff of the northwestern shelf to the Sevastopol coastal area. High values of phytoplankton biomass and chlorophyll a concentration were mainly observed in cold years.

ТИПИЗАЦИЯ ЗИМ В ИЛЕ АЛАТАУ ПО СНЕЖНОСТИ И ЛАВИННОЙ АКТИВНОСТИ

Snow avalanches affect human economic and recreational activities in the mountains. In some avalanche-active winters, they cause significant damage and loss of life. As a result of many years of research, it was found that avalanches strongly depend on the meteorological and synoptic conditions of each individual winter. The main indicator of the danger of the current season is the total and maximum volumes of avalanches in a particular river basin. It strongly depends on the height and water content of the snow cover and the amount of precipitation. The correlation coefficients are 0.36...0.66. In some avalanche-prone winters (1965...66, 1986...87, 2016...17) in the river basin. In Kishi Almaty, the total volume of avalanches reaches 300...500 thousand m3, and in non-avalanche-hazardous winters it does not exceed 20...30 thousand m3. During the years of minimal solar and cyclonic activity in the studied avalanche basin, the highest snow cover heights and avalanche activity are observed. This is probably due to the fact that winter cyclones produce precipitation in the foothill areas in cold years. And the increase in snowfall and avalanche activity is more associated with spring warming and the beginning of snow melting. Studying the meteorological conditions of avalanche formation helps assess the potential danger of the current season. This is of practical importance for planning the work of tourist sites and operational rescue services in the mountains.

Escalating Carbon Export from High-Elevation Rivers in a Warming Climate.

High-elevation mountains have experienced disproportionately rapid warming, yet the effect of warming on the lateral export of terrestrial carbon to rivers remains poorly explored and understood in these regions. Here, we present a long-term data set of dissolved inorganic carbon (DIC) and a more detailed, short-term data set of DIC, δ13CDIC, and organic carbon from two major rivers of the Qinghai-Tibetan Plateau, the Jinsha River (JSR) and the Yalong River (YLR). In the higher-elevation JSR with ∼51% continuous permafrost coverage, warming (>3 °C) and increasing precipitation coincided with substantially increased DIC concentrations by 35% and fluxes by 110%. In the lower-elevation YLR with ∼14% continuous permafrost, such increases did not occur despite a comparable extent of warming. Riverine concentrations of dissolved and particulate organic carbon increased with discharge (mobilization) in both rivers. In the JSR, DIC concentrations transitioned from dilution (decreasing concentration with discharge) in earlier, colder years to chemostasis (relatively constant concentration) in later, warmer years. This changing pattern, together with lighter δ13CDIC under high discharge, suggests that permafrost thawing boosts DIC production and export via enhancing soil respiration and weathering. These findings reveal the predominant role of warming in altering carbon lateral export by escalating concentrations and fluxes and modifying export patterns.

The Evaluation of Sweetcorn (Zea mays saccharata Sturt.) Infestation of Barnyardgrass (Echinochloa crus-galli) Depending on Weather Conditions and Crop Rotation

This paper focuses on the weed species Echinochloa crus-galli, commonly known as barnyardgrass, which is a persistent threat to crop yield and quality, especially in maize (Zea mays) cultivation. It is one of the most problematic weeds in agricultural fields due to its aggressive growth, adaptability to different environmental conditions and prolific seed production. The incidence of Echinochloa crus-galli in maize fields has increased in recent years. This study aims to provide a comprehensive understanding of the characteristics and behavior of Echinochloa crus-galli, and to suggest effective measures to control it. This research on sweetcorn was conducted from 1992 to 2019 at the Research and Education Center Gorzyń, Złotniki branch, which belongs to the Poznań University of Life Sciences. The evaluation of weed infestation was carried out in experiments focusing on chemical weed control in maize. The experiments were designed as a one-factor randomised block design with four field replications. The condition and the degree of weed infestation (number of weeds and fresh weight of weeds) in the control plots was assessed on an annual basis at the end of June and in July. The aim of the study was to evaluate the dynamic changes in the status and extent of barnyardgrass (Echinochloa crus-galli) infestation in maize grown after various other crops in the Wielkopolska region, with a focus on the weather conditions. The study found that barnyardgrass was most likely to occur when maize was sown after winter wheat in a dry and warm year, and least likely when maize was grown in rotation after winter wheat in a cold year with average rainfall. The proportion of barnyardgrass weed mass in the total weed mass was significantly lower after winter rye than after winter wheat, winter oilseed rape and winter triticale. Further research into the biology and ecology of barnyardgrass is key to effectively controlling this weed and safeguarding sweetcorn yields.

Odden Ice Melt Linked to Labrador Sea Ice Expansions and the Great Salinity Anomalies of 1970–1995

AbstractIn each of the last three decades of the 20th century there were unprecedented expansions of sea‐ice over the Labrador Sea basin and influxes of cold fresh water into the subpolar gyre (SPG) which have been described as the Great Salinity Anomalies (GSAs). Employing data for sea surface temperature, salinity, and sea‐ice cover, we propose that these events were downstream consequences of the expansion and subsequent melting of so‐called “Odden” ice formed over the deep basin of the Greenland‐Iceland‐Norway (GIN) Sea in the 1960s, 1970s, and 1980s and additional to the normal East Greenland shelf sea‐ice. We extend previous findings that Odden ice expansions were linked to winter episodes of high atmospheric pressure north of Greenland that directed freezing Arctic winds across the GIN Sea and may also have been associated with increased Arctic sea‐ice volume leading to enhanced ice export through Fram Strait. We show that cold water and ice derived from Odden melting in the summer passed through Denmark Strait and along the East Greenland shelf, and accumulated in the Labrador Sea, creating favorable conditions for winter ice formation during particularly cold years in southwest Greenland. Meltwater from Odden and Labrador Sea ice appeared to break out into the SPG in the fall of 1982 and 1984 respectively and this cold water represents the likely source of the 1982–1985 GSA. These findings further our understanding of the physical processes linking ice formation and melt with ocean circulation in this key component of the climate system.