Changes In Air Temperature Research Articles

A ∼5000 year multiproxy record of summer climate in NE Greenland

The High Arctic plays a vital role in Earth's climate system, and its ecosystems are highly sensitive to global climate change. High Arctic lakes are valuable sentinels of climate change, as their sediments integrate long-term natural climatic fluctuations and anthropogenic influences. Here, we present a high-resolution ∼5000 year-reconstruction of NE Greenland climate variability from Aucella Lake (74°N, 20°E) based on physical, chemical, and biological properties of lake sediments. We use CT-scans, hyperspectral imaging, organic matter, XRD, and diatom analyses to show that changing air temperatures were controlled by a mix of regional climatic changes and local landscape feedbacks. The latest Mid-Holocene (∼5.0–3.8 cal. ka BP) was characterized by relatively warmer conditions, while the onset of the Late-Holocene was marked by abrupt temperature decreases that coincided with the beginning of glacial advances elsewhere (∼3.8–3.4 cal. ka BP). From ∼3.4–2.4 cal. ka BP, the sedimentary record indicated progressive warming, with temperature peaking during the Medieval Climate Anomaly, although temperature rises were punctuated by abrupt, short-lived cold periods. From ∼1.1–0.05 cal. ka BP, the influence of landscape factors over the system diminished. Sedimentary indicators suggested a transition towards a colder, more humid climate, coinciding with the beginning of the Little Ice Age, that was characterized by a marked decrease in air temperature that reached minimum values at the end of this period. The last 50 years at Aucella Lake were marked by abrupt temperature rises, consistent with recently observed anthropogenic global warming. Our results illustrate the importance of high-resolution multiproxy studies for accurately characterizing lake linkages to their environment and climate.

Assessing the Influence Factors of Agricultural Soils’ CH4/N2O Emissions Based on the Revised EDGAR Datasets over Hainan Island in China

Global warming poses a significant environmental challenge, which is primarily driven by the increase in greenhouse gas concentrations. In this study, we aimed to investigate the factors influencing CH4/N2O emissions from agricultural soils over Hainan Island, China, from 2009 to 2018. To achieve this, we selected air temperature, precipitation, and solar radiation as climate factors and categorized farmland as paddy or non-paddy, using revised EDGAR greenhouse gas datasets involving the bias correction method, and geographical detector analysis, multiple linear regression models, and bias sensitivity analysis were used to quantify the sensitivity of climate and land use. The maximum air temperature emerged as the primary factor influencing CH4 emissions, while the mean air temperature predominantly affected N2O emissions. The ratio of paddy field area to city area emerged as the second most influential factor impacting CH4/N2O emissions. The mean CH4/N2O emission intensity from paddy fields was significantly higher (0.42 t·hm−2/0.0068 t·hm−2) compared to that of non-paddy fields (0.04 t·hm−2/0.002 t·hm−2). Changes in maximum air temperature under global warming and crop irrigation practices profoundly affect greenhouse gas emissions on Hainan Island. Specifically, the emission intensities of CH4 and N2O increased by 14.2% and 11.14% for each Kelvin warmer, respectively.

Development of pore water pressure during freeze-thaw cycles in weather conditions

To assess the risk of frost damage to building materials, the mechanisms of pressure development in a material due to freezing under weather conditions should be adequately understood. In this study, we have demonstrated the evolution of pore water pressure in a brick wall during cyclic freezing and thawing caused by changes in air temperature and solar radiation. We developed a coupled hygrothermal and mechanical model of brick walls based on the theory of poromechanics. The calculation results showed that the water pressure in a south facing wall increases significantly during the night in a cold region. For a south facing wall, the surface thaws during the day due to solar radiation and freezes again at night, while the interior remains frozen throughout the day. We conclude that such incomplete freeze-thaw cycles in the weather conditions are much more damaging to building materials than a monotonous repetition of complete freezing and thawing.

Air Temperature Variations in Multiple Layers of the Indonesia Earthquake Based on the Tidal Forces

The air temperature changes in the Palu MW7.5 earthquake in Indonesia on 28 September 2018 were analyzed, based on the additive tectonic stress caused by celestial tidal-generating forces (ATSCTF) and air temperature data from the National Center for Environmental Prediction (NCEP). This paper explored the variation characteristics of three-dimensional stratified of air temperature caused by seismic activity and the coupling relationship between air temperature changes and the tidal force. The background information for air temperature calculation was obtained from the tidal force changes, and the air temperature increment method was used to study the temperature evolution process of different periods in the study area. The results found that the tidal force acting on the critical state earthquake faults may be an important external factor inducing earthquakes, and there was indeed a significant air temperature increase anomaly during the Palu MW7.5 earthquake. The paper also summarized the abnormal characteristics of air temperature caused by seismic activity: the air temperature closer to the land’s surface has greater anomaly amplitude and a wider anomaly area than that of the upper air.

Lighting and thermal factors on human comfort, work performance, and sick building syndrome in the underground building environment

The development of underground space can help cities solve problems such as the unmet demand for land and space. However, there are still many problems to be solved. The comfort of lighting and thermal environment, high work performance, and low prevalence of SBS symptoms play irreplaceable roles in creating a good indoor environment. The main purpose of this study is to investigate the differences in the comfort of lighting and thermal environment, work performance, and SBS symptoms among people living in underground spaces for long and short periods, and to provide optimal temperature and illuminance ranges for balancing these three aspects. A summer survey was conducted in subway stations, including measurements of environmental and physiological parameters, and psychological responses. A total of 952 questionnaires were collected for data analysis. The results show that the comfort of lighting and thermal environment for short-stay occupants is more sensitive to changes in indoor air temperature and illuminance. Reduction of indoor air temperature can improve occupants’ work performance and can reduce SBS symptoms. The optimal temperatures for long-stay and short-stay occupants are 25.6–26.3 °C and 24.5–24.8 °C (or 24.5–25.1 °C), respectively. The optimal illuminance ranges for long-stay and short-stay occupants are > 300.0 lx and > 494.0 lx, respectively. The results of this research contribute to the creation of healthy, comfortable, and beneficial indoor environments in shared underground building spaces.

Trace elements and microbial community composition associated with airborne PM2.5 in wetlands: A case study in Tablas de Daimiel National Park

Tablas de Daimiel National Park (TDNP) is one of the most important wetlands in the Iberian Peninsula. Due to its location near various cities and new industries focused on agricultural waste revalorization, we investigated concurrently the concentrations of particulate matter 2.5 (PM2.5) mass, trace element composition, and associated microbial communities (bacteria and fungi) during a year-long study. The goal of this study was to explore the dependencies among these physicochemical and microbiological parameters on a seasonal time scale. Additionally, we assessed meteorological conditions and back trajectories to shed light on atmospheric mechanisms and sources related to these elements. We found the variability of PM2.5 to be influenced by local meteorological parameters. Through the analysis of crustal enrichment factors (EFs), bivariate correlations, and air mass patterns, we determined that soil resuspension was the primary contributor to elevated metal concentrations in PM2.5 within the park, followed by other minor sources, such as traffic emissions and Sahara dust intrusions. The measured metal levels were used to calculate the ecological risk in the area, resulting in a low ecological risk index (RI) of 52. Shifts in microbial community structure were observed to be mainly driven by changes in air temperature and Cu concentration. The results from this study contribute to a better understanding of the environmental dynamics in TDNP. Taken together, our findings will aid in the development of effective strategies for its conservation and management.

Decadal shifts in the population growth, regeneration, and health of Taxodium distichum in swamps of the Cache River Watershed, Illinois

Population projection models based on long-term trends in regeneration and tree survival can be used to predict the future stability of swamp forest species using water management. Population growth and regeneration of a foundational tree species in North American cypress swamps (Taxodium distichum) were compared in the Cache River watershed of southern Illinois USA over several decades. This study examined T. distichum population growth in several regional swamps within the Cache River watershed along a moisture gradient to model growth, stability, or decline based on data of life history stage transitions, using data from the following time periods: the 1990s, 2002–2011, and 2012–2022. Using data from the 1990s, T. distichum populations in Crawford Tract in Buttonland Swamp were projected to increase over time because of the high frequency of juvenile stages at elevations with growing season drawdown and winter flooding. The situation in Crawford Tract had changed by 2019–2021 because T. distichum seedlings had not transitioned (i.e., saplings and young trees were absent) although no old-growth trees had died during or after the 1990s. In other regional swamps, projection models were constructed over two decades (2006–2021) along a dry-to-wet flood gradient including Section 8 Woods, Deer Pond, Wildcat Bluff, Snake Hole, and Heron Pond. Populations in swamps on the drier end of the gradient had more support from juvenile stages. In a tree health survey in 2022 within the impounded interior of Buttonland Swamp (not Crawford Tract), seventy percent of the old-growth T. distichum trees were stressed or declining. Coupled with the fact that no seedlings or saplings were observed, the populations in the interior of the swamp were not stable. Many factors could further stress these ancient T. distichum including interactions of impoundment with chemicals, disease, and changes in air temperature and precipitation. Overall, the seedling abundance in these swamps increased in these environments from 2012 to 2021, except in the most flooded swamps. From a management perspective, drier conditions were more conducive to the success of the earlier life history stages of T. distichum in these old-growth forests.

Day-flying lepidoptera larvae have a poorer ability to thermoregulate than adults.

Changes to ambient temperatures under climate change may detrimentally impact small ectotherms that rely on their environment for thermoregulation; however, there is currently a limited understanding of insect larval thermoregulation. As holometabolous insects, Lepidoptera differ in morphology, ecology and behaviour across the life cycle, and so it is likely that adults and larvae differ in their capacity to thermoregulate. In this study, we investigated the thermoregulatory capacity (buffering ability) of 14 species of day-flying Lepidoptera, whether this is influenced by body length or gregariousness, and whether it differs between adult and larval life stages. We also investigated what thermoregulation mechanisms are used: microclimate selection (choosing locations with a particular temperature) or behavioural thermoregulation (controlling temperature through other means, such as basking). We found that Lepidoptera larvae differ in their buffering ability between species and body lengths, but gregariousness did not influence buffering ability. Larvae are worse at buffering themselves against changes in air temperature than adults. Therefore Lepidoptera may be more vulnerable to adverse temperature conditions during their larval life stage. Adults and larvae rely on different thermoregulatory mechanisms; adults primarily use behavioural thermoregulation, whereas larvae use microclimate selection. This implies that larvae are highly dependent on the area around their foodplant for effective thermoregulation. These findings have implications for the management of land and species, for example, highlighting the importance of creating and preserving microclimates and vegetation complexity surrounding Lepidoptera foodplants for larval thermoregulation under future climate change.

Operation Parameters Variation of Air Source Heat Pump According to the Outdoor Temperature

Air source heat pumps (ASHP), known as energy efficient systems, emerge as environmentally friendly and economical solutions for building heating. Unfortunately, the operating parameters of ASHPs and accordingly their performance are directly affected by the daily and seasonal temperature changes of the outside air. In this study, change in operation parameters of a selected ASHP with 3.4kW nominal heating capacity is investigated with a calculation method based on the logarithmic mean temperature difference, between -10°C to 18°C outdoor temperature range with 2°C steps, at constant compressor power. The study is verified with published COP data of the manufacturer. Results are shared with graphs that give the variation of refrigerant evaporation and condensation temperature and pressure, COP, and condenser heating load according to outdoor air temperature. A raise from -10°C to 18°C in outdoor temperature, increases the COP value from 3.38 to 5.49. Detection of the increase in evaporation pressure in parallel with the outdoor temperature may allow easy control of the refrigerant charge level with a manometer. This study can be a useful guide for researchers who aim to determine the outdoor temperature dependent operating parameters of an ASHP and for technical personnel who need this information in fields.

Динамика и оценка метеоусловий всесезонного туристско-рекреационного комплекса «Мамисон»

Introduction. By Decree of the Government of Russia dated September 25, 2019 No. 1248, a decision was made to create an all-season tourist and recreational complex “Mamison” on the territory of the Alagirsky district of the Republic of North Ossetia – Alania, in the upper reaches of the Ardon River, the valleys of the Mamikh-Don and Zemegon-Don rivers. One of the most favorable areas is the high-mountain gorge Mamison, where the Zemegon-Don and Kozydon-Don rivers merge, which, downstream, form the Mamikh-Don river. To date, the territory of the Mamison ATRC has been poorly studied in meteorological and hydrological terms. There are practically no studies of the physical properties of snow; the peculiarities of changes in the weight of the snow cover depending on the absolute height have not been identified, as, for example, at the Elbrus ATRC in Kabardino-Balkaria. The work is devoted to the analysis of the dynamics of the average seasonal values of outdoor air temperature, snow cover depth and the amount of precipitation during the cold period (October – May) from 1981 to 2022. On the territory of the Mamison All-Season Tourist and Recreational Complex. Research methods and materials. The work carried out a mathematical and statistical analysis of the meteorological parameters on which the snow avalanche regime depends to the greatest extent. To analyze the average seasonal values of snow depth, air temperatures and total (for the season) amount of precipitation, the work used weather data for the cold period (October – May) obtained at the snow avalanche station (SLS) Roki Pass (from 1981 to 2022). Research results. Mathematical analysis showed that the mid-season snow depth changes linearly, the trend is negative. Mid-season air temperature changes linearly, the trend is also positive. The trend in changes in the seasonal total values of the amount of solid precipitation is positive, the highest amount of precipitation occurs in the spring months – March, April, May (3396 mm, 4809 mm, 4910 mm, respectively). Discussion of research results. The observed changes were manifested in a decrease in the depth of snow cover, a change in precipitation patterns, and an increase in the average seasonal characteristics of the temperature regime. In view of these changes, we can say that the decrease in avalanche activity in the Roki Pass area is associated with interannual changes in the depth of snow cover, which is the main factor in avalanche formation. Conclusions. It was found that from 1981 to 2022, the average annual snow depth decreased by 0.56 cm per year. An expression for the time variation of snow cover height is obtained. Suggestions for practical applications and future research directions. The results obtained have practical significance in the development of mountainous territories and should be taken into account when designing infrastructure facilities of the Mamison ATRC.

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

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

Life on the edge-a changing genetic landscape within an iconic American pika metapopulation over the last half century.

Declines and extirpations of American pika (Ochotona princeps) populations at historically occupied sites started being documented in the literature during the early 2000s. Commensurate with global climate change, many of these losses at peripheral and lower elevation sites have been associated with changes in ambient air temperature and precipitation regimes. Here, we report on a decline in available genetic resources for an iconic American pika metapopulation, located at the southwestern edge of the species distribution in the Bodie Hills of eastern California, USA. Composed of highly fragmented habitat created by hard rock mining, the ore dumps at this site were likely colonized by pikas around the end of the 19th century from nearby natural talus outcrops. Genetic data extracted from both contemporary samples and archived natural history collections allowed us to track population and patch-level genetic diversity for Bodie pikas across three distinct sampling points during the last half- century (1948-1949, 1988-1991, 2013-2015). Reductions in within-population allelic diversity and expected heterozygosity were observed across the full time period. More extensive sampling of extant patches during the 1988-1991 and 2013-2015 periods revealed an increase in population structure and a reduction in effective population size. Furthermore, census records from the last 51 years as well as archived museum samples collected in 1947 from a nearby pika population in the Wassuk range (Nevada, USA) provide further support of the increasing isolation and genetic coalescence occurring in this region. This study highlights the importance of museum samples and long-term monitoring in contextualizing our understanding of population viability.

Changes in apparent temperature and PM2.5 around the Beijing–Tianjin megalopolis under greenhouse gas and stratospheric aerosol intervention scenarios

Abstract. Apparent temperature (AP) and ground-level aerosol pollution (PM2.5) are important factors in human health, particularly in rapidly growing urban centers in the developing world. We quantify how changes in apparent temperature – that is, a combination of 2 m air temperature, relative humidity, surface wind speed, and PM2.5 concentrations – that depend on the same meteorological factors along with future industrial emission policy may impact people in the greater Beijing region. Four Earth system model (ESM) simulations of the modest greenhouse emissions RCP4.5 (Representative Concentration Pathway), the “business-as-usual” RCP8.5, and the stratospheric aerosol intervention G4 geoengineering scenarios are downscaled using both a 10 km resolution dynamic model (Weather Research and Forecasting, WRF) and a statistical approach (Inter-Sectoral Impact Model Intercomparison Project – ISIMIP). We use multiple linear regression models to simulate changes in PM2.5 and the contributions meteorological factors make in controlling seasonal AP and PM2.5. WRF produces warmer winters and cooler summers than ISIMIP both now and in the future. These differences mean that estimates of numbers of days with extreme apparent temperatures vary systematically with downscaling method, as well as between climate models and scenarios. Air temperature changes dominate differences in apparent temperatures between future scenarios even more than they do at present because the reductions in humidity expected under solar geoengineering are overwhelmed by rising vapor pressure due to rising temperatures and the lower wind speeds expected in the region in all future scenarios. Compared with the 2010s, the PM2.5 concentration is projected to decrease by 5.4 µg m−3 in the Beijing–Tianjin province under the G4 scenario during the 2060s from the WRF downscaling but decrease by 7.6 µg m−3 using ISIMIP. The relative risk of five diseases decreases by 1.1 %–6.7 % in G4, RCP4.5, and RCP8.5 using ISIMIP but has a smaller decrease (0.7 %–5.2 %) using WRF. Temperature and humidity differences between scenarios change the relative risk of disease from PM2.5 such that G4 results in 1 %–3 % higher health risks than RCP4.5. Urban centers see larger rises in extreme apparent temperatures than rural surroundings due to differences in land surface type, and since these are also the most densely populated, health impacts will be dominated by the larger rises in apparent temperatures in these urban areas.

Direct and indirect relationships of climate and land use change with food webs in lakes and streams

AbstractAimClimate and land use change can independently affect food web structure. However, their direct and indirect relationships with food webs are not well‐understood. This is particularly relevant for freshwater ecosystems, which are strongly affected by global threats and differ substantially in attributes and functioning. Here, we investigated direct and indirect relationships between climate and land use changes and freshwater food web structure, while considering the differences between lakes and streams.LocationMulticontinental.Time periodCurrent.Major taxa studiedFreshwater taxa.MethodsWe compiled 51 food webs, spanning 12 countries and six continents to investigate the direct and indirect relationships between land use intensity, changes in air temperature and precipitation and food web structure, using structural equation modelling (SEM). We further tested how lake and stream food webs differ in their responses to environmental change by applying a multigroup analysis to our SEM.ResultsWe found that connectance was positively related to both land use intensity and increases in air temperature and precipitation in stream food webs, whereas in lakes, it was only related to temperature. These findings suggest a dominance of generalists where conversion to agriculture and urbanization has been intensified, and temperature has increased. Food web vertical structure was negatively related to land use and increases in air temperature and precipitation, but climatic predictors were only linked to network structure through a negative relationship with the fraction of top consumers.Main conclusionsWhile land use intensity was directly related to food web structure, complex relationships between changes in climate and network topology were mediated by the fraction of top consumers. Also, as food webs in lakes and streams responded differently to land use and climate change, we suggest that their intrinsic characteristics must be explicitly considered to fully understand the effects of global changes on freshwater biodiversity.

Permafrost change and its engineering effects under climate change and airport construction scenarios in northeast China

Climate warming leads to the aggravation of infrastructures and environmental risks in permafrost regions. There are few reports about the interaction between airport runway and permafrost foundation. Based on long term field monitoring, remote sensing and comparative analysis approaches, our study quantitatively investigates the impacts of runway and climate on permafrost in northernmost China, and also the engineering problems are analyzed. Results show that the atmospheric inversion in winter controls the regional permafrost distribution in the study area. Ground surface warmed significantly after vegetation removal because of the runway construction. The maximum temperature difference among the forest, the swamp and the bared gravel can reach to 30 °C in summer. Such surface alterations caused abnormally rapid degradation of permafrost within the context of climate warming. The rate of permafrost table deepening varies from 0.461 to 0.590 m/a over the 2007–2017 periods. Also, the annual mean ground temperature at the 13 m depth increased at a rate of 0.054–0.130 °C /a. Its annual increase value is 0 ∼ 0.47 °C, with an average 0.108 ± 0.124 °C. In turn, permafrost degradation caused runway safety problems, such as the decrease of bearing capacity, increase of longitudinal slope, decrease of planeness, pavement cracks, density decrease of the foundation and cement concrete pavement cavity. However, in the natural places, the permafrost remained relatively stable and didn’t show a continued degradation trend. The permafrost table fluctuated with air temperature changes. Its interannual fluctuation range is 0 ∼ 0.25 m, with an average 0.08 ± 0.08 m. The interannual fluctuation range of ground temperature at the depth of 13 m is 0.01 ∼ 0.10 °C, with an average 0.06 ± 0.03 °C. In addition, the zero curtain phenomena were observed at the study site. Once the zero curtain periods were over, the ground temperature warmed rapidly. These findings have positive implication for new runway design in permafrost regions.

Modeling the Distribution of Atlantic Croaker and Spot in a Dynamic Seascape Using Metabolic Scope

In estuarine and coastal systems, anthropogenic activities and directional changes in global air temperatures have led to increased water temperatures, as well as increased frequency and severity of episodic hypoxia. These alterations have had population-level effects on aquatic organisms, including changes in species-specific distributions. Because physiology is the transfer function connecting environmental conditions to individual behaviors and eventually to population-level effects, we used individual-based models (IBMs) that incorporate changes in metabolic scope as motivation for movement. Our objective was to investigate the effects of temperature and hypoxia on the distribution of Atlantic croaker and spot in Chesapeake Bay. We compared the predicted monthly fish distributions from the IBMs with apparent fish distributions recorded by the VIMS Juvenile Fish Trawl Survey during 1988–2014. IBMs failed to reproduce accurately the apparent spatial distributions of Atlantic croaker and spot. More specifically, compared with the trawl survey, IBMs predicted larger proportions of these two species would be captured in the lower regions of Chesapeake Bay and smaller proportions in the York and Rappahannock rivers. We postulate that, because similar thermal and oxygen conditions were occupied by fish in the IBMs and in the wild, temperature may not be the most important factor motivating the movement of Atlantic croaker and spot in Chesapeake Bay, and other spatial factors (e.g., prey availability) act in concert with temperature and hypoxia to determine the spatial distributions of Atlantic croaker and spot in Chesapeake Bay. Alternatively, surveys used to estimate species occurrences could be biased if gear vulnerability is affected by temperature or oxygen conditions (or both). Additional research is needed to clarify which condition is true or if a combination of these factors (and others) led to discrepancies between predicted and apparent fish distributions based on trawl survey data.

Climate change and natural resources

Climate change is one of the greatest challenges of modern society. Combustion of fossil fuels, ie. anthropogenic emissions of carbon dioxide and other gases that cause the negative effect of the "greenhouse" are a key cause of global climate change. The global increase in air temperature was the trigger for changes in other climatic elements, and above all: evaporation, precipitation regime, the appearance of snow, stormy winds, long-lasting heat waves, etc. The last decade (2010‒2020) was the warmest in the instrumental period. The average annual temperature increased by 1 oC compared to the pre-industrial period. In addition to the increase in the average annual air temperature, there was also an increase in extreme temperatures, and changes in climate indices that are conditioned by the air temperature (frost, summer and tropical days). Such changes in air temperature and climate indices have led to increased evaporation and greater variability of the atmosphere. Climate change has caused a higher frequency and intensity of climate extremes, which have a very unfavorable impact on the environment and natural resources throughout the world. The area of Southeast Europe, ie. the Western Balkans, is one of the most endangered in the world in terms of floods, droughts, long-lasting heat waves and stormy winds. Climate change in the Republik of Srpska and Bosnia and Herzegovina has been particularly pronounced in the last three decades, when they have put increasing pressure on many natural resources, especially water, agricultural land, biodiversity and forest ecosystems. Climate models point to even more intense changes in the near future, which will require a planned approach in planning the resilience of the most vulnerable sectors to climate change on a scientific basis.

Climate change over South America simulated by the Brazilian Earth system model under RCP4.5 and RCP8.5 scenarios

Climate projections simulated by the Brazilian Earth System Model (BESM2.5) under RCP4.5 and RCP8.5 climate scenarios are analyzed based on future changes of surface air temperature (SAT) and precipitation with respect to the historical reference period 1971–2000. Since BESM2.5 is the only climate model developed in a South American country, this study gives a particular emphasis to South American future climate projections. Regarding the surface air temperature, BESM2.5 projects a steady warming throughout the 21st century, with the highest warming over eastern Amazonia, northern Chile and central South America for both scenarios. The SAT changes range between 2 °C and 3–4 °C for RCP4.5 and RCP8.5, respectively. On the other hand, projected precipitation varies over different regions of South America, with decreasing and increasing trends over the Amazon and southern South America, respectively. Interestingly, this study shows contrasting results with respect to extreme precipitation indicators, projecting enhanced extreme events with higher numbers of both consecutive dry days and days in which the precipitation exceeds 20 mm over the southeastern region. The model projects a meridional dipole pattern in the precipitation, with decreasing precipitation and longer dry spells over Northeast Brazil and the East Amazon region and increasing precipitation and shorter dry spells over Northwest South America and West Amazon, that is driven by future changes in the SLP that imposes a meridional gradient over these regions, causing the increase of westerlies that are likely to increase the moisture transport from the Pacific Ocean into western South America and the weakening of the easterlies that transport moisture over eastern South America and East Amazon.

The change and variability of snow cover in Kraków in a 100-year observation series

This article presents the results of research on the changes and variability of snow cover in Kraków in the 100-year period 1921/22–2020/21 and in its two sub-periods covering the years of the slow and rapid territorial, urban and industrial development of Kraków (respectively, 1921/22–1960/61 and 1961/62–2020/21). The long-term variability of the number of days with snow cover, the maximum depth of the snow layer, the dates of the beginning and end of snow cover duration in the winter season, the potential snow cover duration and the index of snow cover stability were analysed. The directions of changes in the snow cover in the last 100 winter seasons in Kraków correspond to the global changes in air temperature presented in the latest IPCC reports: until the end of the 1950s there were no significant trends, or only small trends were observed, whereas from the beginning of the 1960s faster changes in the snow cover duration and maximum seasonal snow depth have been visible. In the last 60 years (1961/62–2020/21), the impact of global changes in Kraków has been joined by the impact of territorial, demographic and industrial development of the city, causing significant negative trends in snow cover with relative values of less than −9% ∙ 10 years−1, both in the case of snow cover duration and its maximum depth in the winter season; these changes are statistically significant. Throughout the whole 100-year period (1921/22–2020/21) and in its second part (1961/62–2020/21), a decrease in snow cover stability has also been observed.

Initial assessment to understand the effect of air temperature on bees as floral visitors in urban orchards

AbstractBees are the most important pollinators and, like many other insects, are facing a global decline that threatens crop pollination services. Both honey bees and some wild bee species are used commercially for pollination, including pollination in blueberry and cherry orchards. In our study, we assessed bee visits to experimental blueberry and cherry orchards immersed in an urban landscape to understand how air-temperature affects the potential contribution of honey bees and wild bees to pollination services. The potential contribution to pollination services was estimated using the Pollination Importance Value index, where the pollen collected by the floral visitor is a determining variable. In our study, bumble bees and honey bees were the most important floral visitors in the orchards, followed by the wild beeAnthophora plumipes. We found that honey bees were affected by changes in air-temperature and their decrease in the potential contribution to pollination services was offset by the niche complementarity provided by bumble bees.Implications for insect conservation Even small changes in air-temperature can alter bee communities by affecting bee species susceptible to low temperatures. Our work is a first assessment of how climate change may affect the complementarity of pollinator communities in orchards. We suggest that strategies to mitigate local air-temperature changes in urban areas, focusing primarily on these species, could potentially have cascading effects that would support the overall pollination services provided by bee communities.