Cold Days Research Articles

Climate Change Impact on Rain-Fed Maize Yield Cultivated with Small-Scale Landowners in Wolaita Zone, Ethiopia

Ethiopia is a country that heavily relies on rainfall-aided cultivation which is carried out by small-scale landowners, leaving it very vulnerable to climate change and fluctuation. The primary goal of this research is to investigate how climate change affects maize yield in Wolaita zone of Ethiopia. The authors were employed a linear regression method to evaluate the relationship between climate parameters and maize yield. Sen's slope magnitude estimator and the Mann-Kendal trend test were used to assess the significance of climate change. The outcome demonstrated that the temperature extreme indices of warm days and the length of warm days were considerably higher by 37.5% and 3.7% of days per year, however, cold days and cold spells were significantly decreased. Over the 1981-2021 periods, there was a significant upward pattern in TXx and TNn at an average of 0.033°C and 0.034°C. There was a considerable decline of 2.3% in the simple daily precipitation intensity index and 33% decreased in extremely heavy precipitation, respectively. The correlation analysis's findings indicated that growing period precipitation and maize outputs were positively correlated, but negatively correlated with maximum and minimum temperatures. Extreme temperature and precipitation were more explained a maize yield than average climate patterns. 12.4%, 14.76%, 13.08%, and 7.95% of maize output variability was attributed by the growing season mean climate conditions, which include precipitation, mean, minimum, and maximum temperature. The variability of maize output was explained by combined impact of precipitation and temperature extremes were 67.7% and 45.0%, respectively. Therefore, livelihood diversification and relevant policy formulation are suggested to adapt inevitable climate change by implementing irrigation and resistant varieties to improve maize yield production.

Investigation of Density factor in Urban Morphology on Micro-Climate Parameters in Cold and Dry Areas (Case Study: Tabriz City, Iran)

In recent decades, in third world countries, especially in the Middle East, the concept of urban micro-climate has undergone many changes in the process of development and construction, leading to environmental crises and the discrete structure of energy consumption in urban blocks. The urban form, the product of morphological changes in recent periods, has had significant effects on the micro-climate of the city. The city of Tabriz in the cold and dry areas of Iran has suffered from the inadequacies of the urban form and adverse effects on the micro-climate of the city as a result of unbalanced development. The main aim of research as parametric study on the interactions between urban morphology and microclimate is to investigate density metric to analysis effect amount in micro-climates. The research is analytical-descriptive and method of collecting data in the form of documents includes literature review, modeling and simulation using Envi-met software and density metric explain modes of a hypothetical in 10 scenarios and are presented in the form of two groups. The construction parts of the hypothetical areas are located in the urban area of Tabriz city, Iran. All scenarios were assumed to be in the same area configuration, where buildings are located in 25 plots of 40 m x 40 m. The result shows Investigation the average ratings obtained from microclimatic simulation of the first group of scenarios shows that by keeping FAR constant and changing BSC, one cannot expect a specific sequence of changes in microclimatic parameters in the space around the buildings but in the case of the second scenario group which is presented with constant BSC and variable FAR, there is a significant sequence in the order of the obtained ranks and the change trend in the average parameters. The results show scenario A2 with FAR 1 and BSC 40% with the lowest average value (3.5) of the total of four parameters of simulating the hottest and coldest day has achieved the best result and is introduced as the best scenario. For future researches, it is possible to propose a more focused investigation on each of the mentioned parameters. DOI: https://doi.org/10.52783/pst.544

Extreme Temperatures and Stroke Mortality: Evidence From a Multi-Country Analysis.

Extreme temperatures contribute significantly to global mortality. While previous studies on temperature and stroke-specific outcomes presented conflicting results, these studies were predominantly limited to single-city or single-country analyses. Their findings are difficult to synthesize due to variations in methodologies and exposure definitions. Within the Multi-Country Multi-City Network, we built a new mortality database for ischemic and hemorrhagic stroke. Applying a unified analysis protocol, we conducted a multinational case-crossover study on the relationship between extreme temperatures and stroke. In the first stage, we fitted a conditional quasi-Poisson regression for daily mortality counts with distributed lag nonlinear models for temperature exposure separately for each city. In the second stage, the cumulative risk from each city was pooled using mixed-effect meta-analyses, accounting for clustering of cities with similar features. We compared temperature-stroke associations across country-level gross domestic product per capita. We computed excess deaths in each city that are attributable to the 2.5% hottest and coldest of days based on each city's temperature distribution. We collected data for a total of 3 443 969 ischemic strokes and 2 454 267 hemorrhagic stroke deaths from 522 cities in 25 countries. For every 1000 ischemic stroke deaths, we found that extreme cold and hot days contributed 9.1 (95% empirical CI, 8.6-9.4) and 2.2 (95% empirical CI, 1.9-2.4) excess deaths, respectively. For every 1000 hemorrhagic stroke deaths, extreme cold and hot days contributed 11.2 (95% empirical CI, 10.9-11.4) and 0.7 (95% empirical CI, 0.5-0.8) excess deaths, respectively. We found that countries with low gross domestic product per capita were at higher risk of heat-related hemorrhagic stroke mortality than countries with high gross domestic product per capita (P=0.02). Both extreme cold and hot temperatures are associated with an increased risk of dying from ischemic and hemorrhagic strokes. As climate change continues to exacerbate these extreme temperatures, interventional strategies are needed to mitigate impacts on stroke mortality, particularly in low-income countries.

The study of heat transfers and thermal performance of different types of solar box cookers

Solar fireplaces are important in remote areas with abundant solar radiation, they are a sustainable and environmentally friendly alternative to traditional cooking methods as they do not emit toxic gases. This study aims to experimentally compare solar box cookers of different designs, materials, and features to understand heat transfer and thermal performance to improve overall efficiency. Four different cases with different materials and features of the box structure are studied: Case 1 - non-tinted wooden sides, case 2 - black tinted wooden sides, case 3 - box with glass sides, and Case 4-black tinted wooden sides and coated inside with aluminum foil. Two designs are compared for each case- one with a front flat mirror and one without. All solar fireplaces consist of an inclined glass facing at an angle to the latitude of Baghdad and a base with black fins. The experiments lasted for three months in various weather conditions including cold, hot, dusty, and sunny days in southern Baghdad, Iraq, positioned at Latitude north and longitude East. Factors such as the intensity of incident radiation, wind speed, and ambient air temperature are taken into account during the cooking period. The results indicate that the third glass-sided box achieved the highest thermal efficiency of 93.7% after 120 minutes. The rice was fully cooked in just 97 minutes, the quickest time ever seen with this type of solar cooker, and it had a thermal efficiency of 88%. The fourth box, lined with aluminum foil inside, succeeded the third book with Rice reaching ripeness at 110 minutes with an 80.5% efficiency.

Removal efficiency of restroom ventilation revisited for short-term evaluation

Ventilation efficiency or contaminant removal efficiency is often evaluated using the ratio between the concentrations in the exhaust air and the room air. This ratio does not truly represent the expectation of ventilation in restrooms, where dynamic airflow fields and sources are more typical. This study focuses on a short-term (10 min) pollutant removal percentage in a residential restroom featuring a dynamic airflow field, particularly with the onset of window-induced stack ventilation during toilet uses. Thirteen ventilation scenarios of a residential restroom were studied using the numerical method that was validated by a mock-up experiment. The scenarios differed in the operation of the exhaust fan and window. Results show that the 10-min pollutant removal percentage of a typical exhaust ventilation system at 10 h-1 air change rate (ACH) is only 68.5%. Under exhaust ventilation, opening the window can introduce both adverse short circuit and favorable stack ventilation depending on the difference between the indoor and outdoor temperatures. As the temperature difference increases from 0 to 12.5 °C, the removal percentage increases from below 50%, a drop due to short circuit, to above 98% thanks to a tripled ventilation rate. The human thermal plume has notable effect on the removal percentage, but its effect can be neglected with the presence of stack ventilation. The hybrid ventilation strategy has impact on perceived air quality and thermal comfort. When the outdoor air is colder, opening the window under exhaust ventilation may increase the current sitting user’s exposure to the self-produced pollutants but can reduce the exposure of the next immediate standing user. In addition, opening the window in cold days will make the toilet user thermally uncomfortable with reduced local temperatures and increased airflow velocities. The study highlights the importance of using the short-term removal percentage to evaluate the performance of restroom ventilation.

The effects of climate and climate change on electric vehicle charging demand in Toronto, Canada

Battery electric vehicles (BEVs) influence total and peak electricity demand, but few studies account for climate when studying these effects. This study quantifies BEV charging demand in the Greater Toronto and Hamilton Area using a detailed trip level approach, accounting for the effect of present and future temperatures on BEV energy consumption. The impact of temperature on charging demand was largest in winter. In 2019, charging demand increases by 52% on an average January day, and up to 82% on extreme days (relative to mild weather conditions). At 30% penetration, BEVs increase peak demand on January’s coldest day by 600–3600 MW (3%–5%), of which 300–700 MW is driven by temperature, depending on the charging scenario. Climate change introduces small changes, increasing summer and decreasing winter charging demand. These results highlight the importance of adjusting for regional climate variation and temperature extremes when analyzing the impact of BEVs on the grid.

Unlocking energy and economic benefits of integrated green envelopes in office building retrofits

Green envelopes show significant potential in energy conservation and thermal comfort enhancement in office buildings. This study presents a comprehensive method integrating field tests, building energy simulations, and optimization in office buildings in Chongqing, China. A 20-year life-cycle cost analysis was conducted to evaluate the benefits of green roofs (using sedum lineare container-type planting modules) and green façades (featuring vertical kudzu greenery systems). The results indicate that green roofs could reduce peak temperatures by up to 34.3 °C, leading to daily energy savings of 12.5 % during summer. Green façades decreased the wall exterior surface temperatures by up to 3.4 °C and 5.1 °C on the test cold and hot days, respectively. The maximum annual building electricity savings per green-modified area was 22.8 kWh/m2 for the poorly-insulated building and 5.4 kWh/m2 for the well-insulated one. This study highlights the cost-effectiveness of green envelopes in improving building efficiency. The optimal retrofit measure for the poorly-insulated building was the combination of green roofs and daylighting dimming control systems, yielding a 20-year life-cycle net savings per floor area of 81.5 CNY/m2. For the well-insulated building, the daylighting dimming control system alone provided optimal net savings per floor area of 26.4 CNY/m2.

Climate change and population persistence in a hibernating marsupial.

Climate change has physiological consequences on organisms, ecosystems and human societies, surpassing the pace of organismal adaptation. Hibernating mammals are particularly vulnerable as winter survival is determined by short-term physiological changes triggered by temperature. In these animals, winter temperatures cannot surpass a certain threshold, above which hibernators arouse from torpor, increasing several fold their energy needs when food is unavailable. Here, we parameterized a numerical model predicting energy consumption in heterothermic species and modelled winter survival at different climate change scenarios. As a model species, we used the arboreal marsupial monito del monte (genus Dromiciops), which is recognized as one of the few South American hibernators. We modelled four climate change scenarios (from optimistic to pessimistic) based on IPCC projections, predicting that northern and coastal populations (Dromiciops bozinovici) will decline because the minimum number of cold days needed to survive the winter will not be attained. These populations are also the most affected by habitat fragmentation and changes in land use. Conversely, Andean and other highland populations, in cooler environments, are predicted to persist and thrive. Given the widespread presence of hibernating mammals around the world, models based on simple physiological parameters, such as this one, are becoming essential for predicting species responses to warming in the short term.

Expanded Graphite (EG) Stabilization of Stearic and Palmitic Acid Mixture for Thermal Management of Photovoltaic Cells

In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to stabilize a phase change material (PCM) with a melting temperature close to 53 °C in order to realize thermal management systems (TMSs) able to store heat at constant temperature during melting and releasing it in crystallization. In particular, stearic and palmitic acid mixture (PA-SA) was shape-stabilized in EG at different concentrations (10, 12 and 14 part per hundred ratio) under vacuum into a rotary evaporation apparatus followed by cold compaction; PA-SA leakage was reduced due to its intercalation between the graphite lamellae, and the thermal conductivity necessary to maximize the heat transfer to a bulk TMS was improved via powder cold compaction, which minimizes voids and creates preferential thermal conductive patterns. The composite materials, stable till 150 °C, were tested by differential scanning calorimetry (DSC) at 1 °C/min to precisely determine the phase transition temperatures and the enthalpic content, which was only slightly reduced from 196 J/g of the neat PCM to 169 J/g due to the very low EG fraction necessary for the stabilization. Despite only the 14:100 EG-to-PA-SA ratio, the system’s thermal conductivity was enhanced 40 times with respect to the neat PCM (from 0.2 to 8.3 W/(m K), value never reached in works present in the literature), with a good convergence of the values evaluated through hot disk tests and laser flash analysis (LFA), finding correlation with both graphitic content and density. In order to completely avoid leaking with the consequent dispersion of PCM in the environment during the final application, all the samples were encapsulated in a PE-made film. The mechanical properties were evaluated with compression tests at 30 °C and 80 °C simulating a possible compressive stress deriving from the contact needed to maintain the TMS position on the rear of the PV cells. Finally, the material response was simulated by imposing thermal cycles into a climatic chamber and reproducing the three hottest and coldest days of summer 2022 of two Italian locations, Verona (Veneto, 45° N, 11° E) and Gela (Sicily, 37° N, 14° E), thus highlighting the thermal management effects with delays in temperature increase and daily peak temperature smoothing. The role of EG is strategic for the processing and the properties of the resulting composites in order to realize a proper compromise between the melting enthalpy of PCM and the thermal conductivity enhancement given by EG.

Evaluating the temperature–mortality relationship over 16 years in Cyprus

ABSTRACT In many regions of the world, the relationship between ambient temperature and mortality is well-documented, but little is known about Cyprus, a Mediterranean island country where climate change is progressing faster than the global average. We Examined the association between daily ambient temperature and all-cause mortality risk in Cyprus. We conducted a time-series analysis with quasipoisson distribution and distributed lag non-linear models to investigate the association between temperature and all-cause mortality from 1 January 2004 to 31 December 2019 in five districts in Cyprus. We then performed a meta-analysis to estimate the overall temperature-mortality dose-response relationship in Cyprus. Excess mortality was computed to determine the public health burden caused by extreme temperatures. We did not find evidence of heterogeneity between the five districts (p = 0.47). The pooled results show that for cold effects, comparing the 1st, 2.5th, and 5th percentiles to the optimal temperature (temperature associated with least mortality, 25 ℃), the overall relative risks of mortality were 1.55 (95% CI: 1.32, 1.82), 1.41 (95% CI: 1.21, 1.64), and 1.32 (95% CI: 1.15, 1.52), respectively. For heat effects, the overall relative risks of mortality at the 95th, 97.5th and 99th percentiles were 1.10 (95% CI: 1.04, 1.16), 1.17 (95% CI: 1.07, 1.29), and 1.29 (95% CI: 1.11, 1.5), respectively. The excess mortality attributable to cold days accounted for 8.0 deaths (95% empirical CI: 4.5–10.8) for every 100 deaths, while the excess mortality attributable to heat days accounted for 1.3 deaths (95% empirical CI: 0.7–1.7) for every 100 deaths. The results prompt additional research into environmental risk prevention in this under-studied hot and dry region that could experience disproportionate climate change related exposures. Implications: The quantification of excess mortality attributable to temperature extremes shows an urgent need for targeted public health interventions and climate adaptation strategies in Cyprus and similar regions facing rapid climate change. Future steps should look into subpopulation sensitivity, coping strategies, and adaptive interventions to reduce potential future risks.

Extreme precipitation and temperature indices under future climate change in central Asia based on CORDEX-CORE

The present study analyzes the projected changes of extreme climate indices over Central Asia using regional climate model (RCM) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX) - Coordinated Output for Regional Evaluations (CORE). The extreme indices are based on precipitation and temperature and are inspected for present (1981–2005) and future periods - near- (2031–2055) and far-future (2071–2095) - to assess the long-term climate change under the representative concentration pathway RCP8.5. Projected changes are analyzed for three different model ensembles. These ensembles are based on CORDEX-Central Asia (ENS_CAS, four ensemble members) and CORDEX-East Asia (ENS_EAS, six ensemble members), and a combination of both (ENS, ten ensemble members) for our study area centered over high mountain Asia, called Central East Asia (CEAS). For precipitation indices, an increase of consecutive dry days (CDD) in ENS_EAS and a slight to moderate decrease in northern parts in ENS_CAS during near-future is observed. Consecutive wet days (CWD), very heavy precipitation events (R20mm), maximum one-day precipitation (RX1day), and very wet days (R95p) are projected to increase in most areas. All indices show a further intensification towards the end of the century over large parts of the domain, e.g., + 7.8% / +5.6 days for CDD, + 96.6% / +0.26 days for R20mm, and + 19.7% for RX1day as median of ENS over CEAS. For temperature indices, the ensembles project a strong increase over the high mountain regions and southern parts for consecutive summer days (CSU, + 108.5% / +38.3 days), heat wave duration index (HWDI, + 1379.1% / +91.37 days), and the percentage of very hot days (TX90p, + 391.1% / +34.54 days). Accordingly, the number of consecutive frost days (CFD, -43.7% / -25.2 days) and the percentage of very cold days (TX10p, -83.4% / -8.13 days) are projected to decrease. The first-time usage of CORDEX-CORE and the larger ensemble size by considering simulations from overlapping domains increase the robustness of the findings from earlier studies. However, some discrepancies in the projected changes prevail among the different RCMs being part of the two CORDEX-domains and in specific landscapes like complex mountainous or lake areas. These uncertainties may be tackled by further model development with improved land-surface processes and potentially higher spatial resolution.

Comparative analysis on the mechanism of climate responsiveness strategies on indoor thermal performance of Yaodong dwellings in the Loess Plateau region of China

The vast rural architecture, while contributing significantly to enormous building energy consumption, also brings about substantial energy-saving potential. This underscores the need for a profound understanding of sustainable and intelligent green construction practices for vernacular dwellings. This study focuses on investigating the mechanisms of climate-responsive strategies on the indoor thermal environment of traditional dwellings in the Loess Plateau region, using the cave dwelling, known as Yaodong in Yulin, as a case study. Through on-site measurements, the study examines the effectiveness of climate responsiveness strategies on the indoor thermal conditions of different types of Yaodong (cliff-side style and independent style). Simultaneously, dynamic simulations are employed to analyze energy consumption of heating season (ECHP) and indoor temperature on the coldest day, while adjusting variable parameters of various passive strategies to identify the influences of factors affecting the indoor thermal performance of different types of Yaodong. The results indicate that the traditional Yaodong, employing passive design methods can contribute to enhancing indoor comfort under adverse climate conditions. The average indoor temperatures of cliff-side and independent Yaodong bedrooms are −1.9 °C and −3.2 °C, respectively, compared to the outdoor temperature of −12.8 °C, outperforming modern brick dwellings with an average indoor temperature of −9.3 °C. For cliff-side Yaodong, factors such as orientation, window-to-wall ratio (WWR), the aspect ratio, and sunspace prove to be the four most critical elements influencing indoor thermal performance. For independent Yaodong, the ranking of key factors is orientation, the aspect ratio, wall thermal resistance, and window-to-wall ratio. This study can provide guidance and reference for the preservation and revitalization of cave dwellings in the Loess Plateau region.

Temperature exposure and health inequality

This paper analyzes the relationship among temperature exposure, health inequality, and adaptive behavior in China, a country with diverse climate zones ranging from the cold, arid northwest to the warm, humid south. Utilizing follow-up survey data spanning from 2000 to 2015, this paper constructs a measure of health inequality at the community level. Our findings reveal that extremely cold or hot days increase the health inequality at the community level. Specifically, with each incremental rise in the day’s extreme temperature, the Gini coefficient of community health rises by 0.0032, which constitutes approximately 0.4% of the community average. Furthermore, vulnerable communities, which are characterized by low average income, education levels, per capita electricity consumption, and urbanization, are highly susceptible to the effects of extreme temperatures on health equality. From the perspective of adaptive behavior, residents in high-income communities exhibit elevated electricity consumption and engage in frequent preventive health check-ups during extreme temperature exposure. This phenomenon may exacerbate social polarization because well-resourced individuals and communities are better equipped to withstand the challenges posed by climate change and extreme weather events compared with impoverished ones. Addressing this disparity requires local managers to implement comprehensive policies and interventions that can enhance the adaptability of low-income communities, improve public health facilities, and promote social equity.

Developing a geographical-meteorological indicator system and evaluating prediction models for alveolar echinococcosis in China.

Geographical and meteorological factors have been reported to influence the prevalence of echinococcosis, but there's a lack of indicator system and model. To provide further insight into the impact of geographical and meteorological factors on AE prevalence and establish a theoretical basis for prevention and control. Principal component and regression analysis were used to screen and establish a three-level indicator system. Relative weights were examined to determine the impact of each indicator, and five mathematical models were compared to identify the best predictive model for AE epidemic levels. By analyzing the data downloaded from the China Meteorological Data Service Center and Geospatial Data Cloud, we established the KCBIS, including 50 basic indicators which could be directly obtained online, 15 characteristic indicators which were linear combination of the basic indicators and showed a linear relationship with AE epidemic, and 8 key indicators which were characteristic indicators with a clearer relationships and fewer mixed effects. The relative weight analysis revealed that monthly precipitation, monthly cold days, the difference between negative and positive temperature anomalies, basic air temperature conditions, altitude, the difference between positive and negative atmospheric pressure anomalies, monthy extremely hot days, and monthly fresh breeze days were correlated with the natural logarithm of AE prevalence, with sequential decreases in their relative weights. The multinomial logistic regression model was the best predictor at epidemic levels 1, 3, 5, and 6, whereas the CART model was the best predictor at epidemic levels 2, 4, and 5.

Effects of 2 wintering practices on behavioral and physiological indicators of welfare of nonlactating, pregnant dairy cattle in a pasture-based system

In countries with pasture-based dairy systems and relatively cold winters, such as New Zealand, it is common to manage pregnant, nonlactating cows on forage crop paddocks rather than pasture, due to slow pasture growth rates. Wintering dairy cattle on grazed crops can compromise welfare if wet and muddy underfoot conditions occur, which can reduce lying. This study investigated behavioral and physiological indicators of welfare of cows under 2 wintering practices: cows managed on and grazed kale crop (Brassica oleracea), and cows managed on pasture with baled hay. Following dry-off (d 0), 80 cows were randomly assigned to 1 of the 2 wintering practices (40 cows/practice) and monitored between d 4 and 32 (phase 1). During this period, lying and stepping behavior was continuously recorded using leg-based accelerometers. Blood samples were obtained at d 0 and 32 for measurements of thyroxine (T4), nonesterified fatty acids (NEFA), white blood cells (WBC), and red blood cells. All data for phase 1 were presented descriptively due to the lack of treatment replication. Daily mean air temperature during this period was 5.2°C (range: 0.0-10.7°C), and rainfall was 1.1 mm/d (range: 0-5.6mm/d). Between d 4 and 32, cows in both groups spent similar amounts of time lying (pasture with hay cows: 8.9 h/24 h ± 2.57, kale crop cows: 8.7 h/24 h ± 3.06, mean ± SEM). Both groups reduced their lying on wet and cold days, and there was evidence of rebound lying once unfavorable weather conditions stopped. Cows on kale crop had numerically higher NEFA and lower WBC compared with cows managed on pasture, although most physiological values were within normal ranges. In a second phase of the study (d 34 and 35), cows were managed under controlled, replicated conditions in the 2 wintering practices using typical on-farm stocking rates (2 or 4 cows per group in the pasture with hay and kale crop treatments, respectively; n = 10 groups/treatment). During this period, cow behavior, skin and surface temperatures, hygiene scores, feed intakes, and ground conditions were measured. Weather conditions during the 48-h exposure were mostly cold and dry (mean air temperature: 7.8°C, range: -2.2 to 20.5°C). Cows managed on pasture with hay spent more time lying down on the first day of exposure; however, this was likely due to less space being available to kale cows on this day. Cows managed on pasture with hay ruminated more than cows on kale crop on both days of observations (d 1: 37.9% vs. 30.9% of observations, d 2: 36.8% vs. 28.7% of observations for pasture with hay and kale crop groups, respectively) and were lying more often in postures indicative of greater thermal comfort. Cows managed on pasture with hay had higher skin and surface temperatures compared with cows on kale crop, whereas cows on kale crop had dirtier coats. Results suggest that opportunities for thermal comfort were greater for cows managed on pasture with hay bales, which may be due to increased rumination activities and more insulated lying areas.

Characteristics of cold events in the eastern China: Perspective from five metropolitan regions

AbstractThis study investigates the characteristics of cold events affecting eastern China during November–March of 1979–2018 using station observations and the ERA5 reanalysis, focusing five major cities (Beijing, Zhengzhou, Wuhan, Shanghai and Guangzhou) for their high vulnerability and distinct local thermal conditions than the broader climate regimes. For each city, cold day (CD) (one or more continuous days where the temperature falls below the local 5th percentiles) and cold surge (CS) (a period of 1–3 days with a total temperature decrease exceeding 8°C) were both examined in aspects of occurrence frequency, circulation characteristics and health impacts. Results show that the northern cities are relatively more/less exposed to CD/CS than the southern cities. At all five cities, the two types of events rarely coincide and exhibit distinct multiple‐year variations, as CD and CS are, respectively, dominated by continental‐ and regional‐scale circulations. However, both types of events are associated with the interplay of the East Asia trough at 300 hPa and the Siberian high, Aleutian low and subtropical high at 850 hPa. Results also show that during CDs in these cities, the effective temperatures (ET), which take into account of the near‐surface wind speed and humidity, are often about 5°C lower than the actual temperatures. The ET decreases are larger than the actual temperature drops in most CSs, yet in specific scenarios (primarily in Beijing and Zhengzhou when the temperature drop is relatively small), the ET drop can be less pronounced, as the possible decrease of wind speed and/or humidity can partially mitigate the ET decrease caused by dropping temperatures. These underline the complexity of health impacts of cold events, which vary regionally due to differences in covariations of temperature, wind speed and relative humidity. There aspects are worthy of further investigation.

Modulated Trends in Arctic Surface Air Temperature Extremes as a Fingerprint of Climate Change

Abstract Strengthened by polar amplification, Arctic warming provides direct evidence for global climate change. This analysis shows how Arctic surface air temperature (SAT) extremes have changed throughout time. Using ERA5, we demonstrate a pan-Arctic (>60°N) significant upward SAT trend of +0.62°C decade−1 since 1979. Due to this warming, the warmest days of each month in the 1980s to 1990s would be considered average today, while the present coldest days would be regarded as normal in the 1980s to 1990s. Over 1979–2021, there was a 2°C (or 7%) reduction of pan-Arctic SAT seasonal cycle, which resulted in warming of the cold SAT extremes by a factor of 2 relative to the SAT trend and dampened trends of the warm SAT extremes by roughly 25%. Since 1979, autumn has seen the strongest increasing trends in daily maximum and minimum temperatures, as well as counts of days with SAT above the 90th percentile and decreasing trends in counts of days with SAT below the 10th percentile, consistent with rapid Arctic sea ice decline and enhanced air–ocean heat fluxes. The modulated SAT seasonal signal has a significant impact on the timing of extremely strong monthly cold and warm spells. The dampening of the SAT seasonal fluctuations is likely to continue to increase as more sea ice melts and upper-ocean warming persists. As a result, the Arctic winter cold SAT extremes may continue to exhibit a faster rate of change than that of the summer warm SAT extremes as the Arctic continues to warm. Significance Statement As a result of global warming, the Arctic Ocean’s sea ice is receding, exposing more and more areas to air–sea interactions. This reduces the range of seasonal changes in Arctic surface air temperatures (SAT). Since 1979, the reduced seasonal SAT signal has decreased the trend of warm SAT extremes by 25% over the background warming trend and doubled the trend of cold SAT extremes relative to SAT trends. A substantial number of warm and cold spells would not have been identified as exceptional if the reduction of the Arctic SAT seasonal amplitudes had not been taken into account. As the Arctic continues to warm and sea ice continues to diminish, seasonal SAT fluctuations will become more dampened, with the rate of decreasing winter SAT extremes exceeding the rate of increasing summer SAT extremes.

Cold spells in the city of Poznań and their circulation conditions

This study analyzed the occurrence of cold days, very cold days and cold spells in Poznań in the years 2008/09-2022/23. A cold day was defined as a day with Tmax < 0.0 °C and ≥-10.0 °C, whereas a very cold day was defined as a day with Tmax <-10.0 °C. In the next step, cold spells were determined, which are sequences of at least 5 days with Tmax < 0.0 °C. Circulation conditions were determined based on daily values of sea-level pressure, the height of the 500 hPa isobaric surface, as well as their anomalies and air temperature anomalies at the 850 hPa isobaric level. The conducted research showed a decrease in the number of cold and very cold days in Poznań in the years 2008/09-2022/23. A variation in the number of cold and very cold days and cold spells was noted across the city area, which is a consequence of the form of land use. The occurrence of cold spells in Poznań was associated with higher than average sea-level pressure.

Managing Extreme Climatic Variability: A Study of Rice Based Farming in Assam, India

Assam has been experiencing the adverse effects of climate change and its most common manifestation is the increasing frequency of extreme flood in the pre-monsoon, monsoon and post-monsoon seasons. Lakhimpur and Dhemaji are the two districts that have been subjected to severe flood every year and in recent years have been experiencing soil erosion, sand-silt deposition in rice growing areas. The present study was therefore attempted in these two districts to find out the impact of extreme events in agriculture and social activities of the farmers in flood affected areas and to find out their responses and coping mechanisms during extreme climate variability. The result of the study revealed that both men and women farmers have been experiencing changes in the weather patterns with longer duration of hotter days and shorter duration of cold days. They have been experiencing frequent drought and frequent flood accompanied by soil erosion, sand and silt deposition in their rice fields affecting their farming activities. The area and production of rice/pulses/oilseeds had decreased to a great extent due to sand-silt deposition. During extreme flood livestock and fish production also decreased due to diseases and decreasing swampy areas/ponds. Availability of food, fodder and fuel had been affected for which the time taken for collecting fodder and fuel has increased. The impact of extreme climate events resulted in increasing indebtedness, wage labour, migration of young men in search of employment and school dropout of children. In response to such extreme climate events farmers had learned to adapt themselves through diversified farming by branching out into livestock production, change in cropping pattern, increasing the area of rabi crops cultivation, adopting non-farm activities such as wage labour in neighbouring districts/states, shop keeping, fishing and selling dry fish etc. women have adopted non-farm activities such as weaving, fishing and selling local brew. The priority adaptation needs of these men and women farmers are stress tolerant varieties of rice in flood affected areas, stress tolerant crops in sand deposited areas, training on scientific crop and livestock production, poultry etc. Women need training on improved techniques of loom and designing so as to fetch good price of their products as well as livestock and poultry production.

Extreme temperatures and morbidity in old age in Europe

Understanding the relationship between extreme temperatures and health among older adults is of paramount importance for public health in ageing societies. This study aims to enhance our understanding of the impact of extreme temperatures on morbidity, i.e. the risk of being hospitalised, using medications for heart conditions, and experiencing the onset of cardiovascular diseases (CVDs) among older adults in Europe (65+ years old) using five waves from the Survey of Health, Ageing and Retirement in Europe (SHARE, 2004–2015). It also explores heterogeneity in this impact depending on an array of factors that affect exposure and vulnerability to climate, including geographical location, gender, age, educational level, having a partner/child and living in an urban or a rural area. Results from individual fixed-effects models show that extremely cold temperatures increase the risk of being hospitalised and suffering from CVDs, while heat exposure has no noteworthy effect. Broken down by geographical location, the results indicate that one additional extremely cold day influences the risk of hospitalisation in the coldest and the warmest European regions, while extreme heat influences this risk in the warmest European regions. Finally, the oldest old and low educated individuals appear to be the most vulnerable social groups. The study concludes by discussing the advantages and the limitations of using survey data to study climate and health, and the strategies suggested by the relevant literature to prevent temperature-related illness.