Annual Temperature Fluctuations Research Articles

Climate change and lethal violence: a global analysis

Purpose The study aims to uncover the relationship between rising temperatures, increased greenhouse gas emissions and the prevalence of lethal violence, encompassing suicides and homicides. It also sought to identify how climate change affects different economic strata in countries, notably in high and middle-income nations, and across Asia and Africa. Design/methodology/approach This study rigorously explored the link between global climate change and lethal violence across 201 countries from 1970 to 2020. Climate change was measured using annual surface temperature fluctuations and greenhouse gas emissions, while lethal violence was estimated using data on suicides and homicides. Findings The analysis revealed significant positive associations between escalating temperatures, heightened greenhouse gas emissions and lethal violence. These connections were evident across different economic levels and geographic regions in Asia and Africa. Originality/value This study emphasizes the urgent need for comprehensive interventions to combat human-induced climate change and mitigate its extensive negative impacts on society, particularly its association with increased violent behavior.

Experimental study on the thermal performance of non-white near-infrared solar reflective coatings in a permafrost region

Solar reflective coating (SRC) offers a method to reduce surface temperature without the need for additional energy consumption, making it highly applicable in permafrost regions. However, many SRCs with high solar reflectance are white, which can cause glare and not meet the aesthetic pavement requirements of high-grade highways. Herein, we developed two non-white SRCs (black and gray) designed to achieve low reflectance in the visible spectrum while maintaining high reflectance in the near-infrared region. We then evaluated the thermal performance of a white SRC, two non-white SRCs and asphalt (as a control) by analyzing surface temperature, ground temperature, and the heat flux between the soil and pavement in a permafrost region of the Qinghai-Tibet Plateau. The results showed that three SRCs reduced the annual mean surface temperature and surface temperature fluctuation compared to the asphalt. The white SRC exhibited annual heat release, whereas the non-white SRCs (black and gray) reduced heat absorption by 34.53% and 69.44%, respectively, compared to the asphalt. By directly reducing the heat absorption of asphalt, the non-white SRCs can potentially slow permafrost degradation beneath asphalt pavements. This study provides a theoretical foundation and technical support for applying non-white near-infrared SRC on high-grade highways in permafrost regions.

An investigation into the physical factors that control slow mass movements

The behavior of slow mass movements like soil creep is well known to be governed by soil composition, slope, and cycles in temperature and rainfall. However, their magnitude and importance vary dramatically in often unpredictable ways, with important consequences for creep rate and infrastructure damage prediction. Here, we present long-term (2015–2022) creep measurements for four regions of the UK characterized by intense mass movement activity but different bedrock lithologies. We also obtained co-located temperature and precipitation time series over this period, as well as local measurements of slope and soil thickness and composition. Our goal was to deconvolve the relative importance of each observable on creep behavior. Our results imply that parent lithology governs first-order creep rates indirectly via hillslope repose angles and soil thickness and composition. Rates of ground movement on peat and sandstone soils are dictated by annual fluctuations in precipitation and temperature, respectively. By employing a simple error-minimizing regression routine, we demonstrate how creep rates can be predicted in these settings as a function of climatological observables. Over thinner limestone and thicker clay soils, however, our model fails: in these settings, we suggest that creep behavior is instead dominated by variations in regolith thickness, and slope and clay mineral content, respectively.

Local habitat heterogeneity rivals regional differences in coral thermal tolerance

AbstractVariable temperature regimes that expose corals to sublethal heat stress have been recognized as a mechanism to increase coral thermal tolerance and lessen coral bleaching. However, there is a need to better understand which thermal regimes maximize coral stress hardening. Here, standardized thermal stress assays were used to determine the relative thermal tolerance of three divergent genera of corals (Acropora, Pocillopora, Porites) originating from six reef sites representing an increasing gradient of annual mean diel temperature fluctuations of 1–3 °C day−1. Bleaching severity and dark-acclimated photochemical yield (i.e., Fv/Fm) were quantified following exposure to five temperature treatments ranging from 23.0 to 36.3 °C. The greatest thermal tolerance (i.e., Fv/Fm effective dose 50) was found at the site with intermediate mean diel temperature variability (2.2 °C day−1), suggesting there is an optimal priming exposure that leads to maximal thermal tolerance. Interestingly, Acropora and Pocillopora originating from the least thermally variable regimes (< 1.3 °C day−1) had lower thermal tolerance than corals from the most variable sites (> 2.8 °C day−1), whereas the opposite was true for Porites, suggesting divergent responses across taxa. Remarkably, comparisons across global studies revealed that the range in coral thermal tolerance uncovered in this study across a single reef (< 5 km) were as large as differences observed across vast latitudinal gradients (300–900 km). This finding indicates that local gene flow could improve thermal tolerance between habitats. However, as climate change continues, exposure to intensifying marine heatwaves is already compromising thermal priming as a mechanism to enhance coral thermal tolerance and bleaching resistance.

Temporal partitioning of Chironomidae emergence in an insular, tropical rainforest stream

Annual water temperature variation strongly influences larval growth of aquatic insects in streams located in temperate regions or at high elevations, which produces cohorts with highly synchronized emergence periods and short average annual durations of emergence. Studies of Chironomidae in tropical streams indicate that species in these habitats have longer average durations of emergence due to reduced annual variation in water temperature. We used emergence trap data collected over one year from Quebrada Prieta (El Verde Field Station, Puerto Rico) to test the prediction that chironomids of an insular rainforest stream should have longer average annual durations of emergence than chironomids in both temperate streams and mainland streams in continental tropical regions. Taxa richness was relatively low with twenty-eight Chironomidae taxa collected from Quebrada Prieta. Emergence patterns of the most common taxa demonstrated some seasonally with the highest emergence generally occurring during the dry season (January through April). The estimated average emergence duration of Chironomidae in Quebrada Prieta was 205 days/species/year, which was greater than estimates of average durations for chironomids of three streams in Pennsylvania, USA (70 days/species/year), 6 streams in Minnesota, USA (89 days/species/year), and four streams in Guanacaste National Park in northwestern Costa Rica (116 days/species/year). The emergence duration for the chironomid community in Quebrada Prieta was most similar to another tropical, mountain stream in the Democratic Republic of the Congo (255 days/species/year). Although many taxa emerged throughout the one-year sampling period, some taxa in Quebrada Prieta had distinct emergence peaks. This demonstrates that although environmental conditions are stable enough to allow for emergence throughout the year for many species, there is some seasonality in the development of chironomid taxa in this tropical stream. These results are consistent with predictions that invertebrates in tropical streams will have longer, less synchronous emergence periods than species in temperate regions with high annual fluctuations in temperature. However, this research is also similar to several other studies that have identified seasonal emergence peaks in tropical chironomids which demonstrates a need to better understand the exogenous cues that affect these patterns.

Climate Change Shocks and Credit Risk of Financial Institutions: Evidence from China’s Commercial Banks

ABSTRACT As global climate risk is looming in recent years, the climate risks faced by financial institutions are also increasing. Effectively quantifying and assessing climate-related financial risks is of great significance for financial institutions to establish risk management mechanisms. Accordingly, choosing Chinese commercial bank data from 2007 to 2019, this paper quantitatively evaluates the influence of climate change shock on the banks’ credit risk by taking the annual temperature fluctuation in cities as the core index to characterize the climate change degree. It is found that annual average temperature rise can significantly increase the credit risk level of commercial banks. Heterogeneity analysis indicates that small-scale banks, rural commercial banks, and commercial banks with higher marketization levels are more sensitive to climate change. Further analysis shows summer and autumn temperature changes have the most prominent impact on banks’ credit risk. Moreover, there is no obvious nonlinear relationship or lagged effects between annual temperature change and banks’ credit risk in our dataset.

Pre-landing Assessment of the Surface and Shallow Subsurface Thermal Setting of Mare Crisium of the Moon for the Heat Flow Measurement Planned on the Blue Ghost 1 Mission

In 2024, under NASA’s Commercial Lunar Payload Services initiative, a robotic lander will touch down in Mare Crisium of the Moon and deploy a heat flow probe. Ideally, the probe should penetrate the regolith deep enough (1.5–2 m) to avoid the influence of insolation, but it is a major challenge to excavate such a hole on a robotic mission. The present study assesses the insolation-induced temperature fluctuation in the shallower subsurface of the landing site in case the heat flow probe does not reach past that depth. The assessment was based on a newly constructed, one-dimensional heat conduction model, which accounted for the history of solar heat intake at the landing site for the past 100 yr. The thermal properties of the subsurface regolith of the model were constrained by the previous surface temperature observations by flyovers of NASA’s Lunar Reconnaissance Orbiter and the subsurface thermal measurement data from Apollo 17. The model showed that the amplitude of the insolation-induced annual subsurface temperature fluctuation is modulated by the 18.6 yr period precession of the Moon. The model also showed that the amplitude of this annual wave would be at (or close to) its minimum in 2024, when the mission would take place. Even though the thermal wave may be felt at depths greater than 1.5 m, because of its small amplitude, the thermal gradient in the depth range from 1 to 1.5 m would be within several percent of the gradient representative of the endogenic heat flow.

Middle Eocene Paleoclimate recorded in halite deposits in Jianghan Basin, central China

The Eocene epoch in China is characterized by the abundance of salt-mudstone rhythms in the eastern basins, which are considered ideal for the reconstruction of eastern Asian paleoclimate. Salt deposits correspond to relatively extreme climate events. However, due to insufficient independent temperature proxies, there is a lack of paleotemperature records obtained from salt laminae depositions. Here, we measured fluid inclusion by microthermometry to study halite samples from the third member of the Qianjiang Formation in the Qianjiang Depression, Jianghan Basin, central China. Following approprite sample preparation measures, homogenization temperatures (Th) of primary fluid inclusions in chevron and cumulate halite crystals that can represent air temperatures at the time of deposition, were plotted in two separate ranges: 12.1–29.9 °C and 36.2–47.2 °C, representing winter and summer temperature fluctuations, respectively. In comparison with modern evaporative environments and temperatures calculated from oxygen isotopes in mudstones and dolomites that are spatially related to our halite samples it was found that the annual temperature fluctuations in the middle Eocene of the Jianghan Basin has been very similar to the Badwater Basin in Death Valley. Furthermore, the salt rhythms were mainly controlled by water influx and evaporation capacity rather than the elevated temperatures. Ultimately, statistical analysis of the homogenization temperature data and cross-plots of the carbon and oxygen isotopes revealed a monsoon climate that could have been more likely to prevail during the middle Eocene epoch of the Jianghan Basin.

Scalable and dynamically passive thermal regulation over solar wavelengths enabled by phase-transition metamaterials

About 20% of all energy utilized worldwide is allocated to regulate the temperature of buildings through heating and cooling in response to seasonal changes. Numerous cutting-edge, low-carbon-footprint innovations have recently been demonstrated to assist resolve this issue, including passive radiative cooling and sun heating. Their accessibility is nevertheless constrained to particular seasons or climate zones by the steady and one-sided control of temperature. Here, taking advantage of recent breakthroughs in photonic manipulation and radiative heat transfer technology, we propose phase-transition metamaterials with dynamically passive and radiative thermal regulation capability for temperature control that can be scaled up for application in buildings. At a critical temperature, the sun absorptance of this metafilm can self-modulate from 0.9 to 0.18 as a result of temperature changes. This metafilm is made of reflective silver (Ag) thin film on top of polyethylene (PE) film with vanadium dioxide (VO2) nanoparticles embedded in it. By varying the volume percentages of the VO2 nanoparticles and the PE matrix thickness, this metafilm’s optical performance can be tailored. We model the inactive dynamic thermal regulator’s equilibrium temperature response to diurnal temperature swings. The industrial film extrusion approach has the potential to produce the nanoparticles embedded into the polymer structure, and the physical vapor deposition method can deposit the Ag thin film scalably, both of which are encouraging for scale-up deployment. This passive radiative heat thermal management technology can be potentially applied to regions with extreme annual temperature fluctuations.

Monitoring the Permafrost Conditions along Pipeline Routes in Central Yakutia, Russia

Pipelines are critical infrastructure for Yakutia, transporting vital supplies to communities in this vast northern region. The pipeline routes in central Yakutia traverse areas of ice-rich permafrost that is sensitive to temperature changes. This study examined the thermal state of permafrost in undisturbed and disturbed settings along the Lena River to Mundulakh Reservoir water pipeline and the Mastakh to Yakutsk gas pipeline and considered the effects of climatic fluctuations and surface disturbances (forest removal and wildfire) over the monitoring periods of 28 and 18 years, respectively. The geocryological conditions in the study area, as well as the methods of permafrost thermal monitoring, are described. The observation results demonstrated significant increases in the mean annual ground temperature in the upper permafrost layers, as well as in the active-layer thickness following fire and post-fire clearing. At some sites, progressive deepening of the active layer caused the formation of taliks and reached the top of massive ground ice, initiating permafrost degradation. The development of extreme ground temperatures in the layer of annual temperature fluctuations was analyzed according to the combination of seasonal and annual meteorological conditions and the type of anthropogenic impact. The research results can be extrapolated to similar anthropogenic landscapes.

Spatial-Temporal Analysis of Physio-Climatic changes in Tawang- Chu River Basin, Eastern Himalaya in India

The Tawang-Chu River Basin of the eastern Himalayas is a heterogenous region that is highly vulnerable to climate change. The changing temperature patterns in this mountain river basin play a vital role in changing the ecological system and inter-ecological nexus. Landsat satellite images were used to analyze spatio-temporal changes in Land Use and Land Cover (LULC) patterns in the basin. The changing trends of Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) were analyzed (at intervals of five years) using Landsat data. Changes in rainfall trends were analyzed using the Mann-Kendall test. The results show that fluctuations in annual temperature and increasing rainfall uncertainties are affecting LULC vegetation health.

Effect of pre-sowing seed treatment with polyfunctional products on the chlorophyll and nitrogen content in winter wheat plants in the conditions of the Stavropol Territory

The article presents the results of studies on the effectiveness of pre-sowing treatment of winter wheat seeds with multifunctional preparations Icar Sids, Sprintalga and Microfol Combi, conducted at the experimental field and in the laboratory of the Department of Plant Physiology of the North Caucasian FNAC in 2018–2021. The soil of the experimental site is ordinary medium–sized low–humus heavy loamy black soil, with very low availability of mineral nitrogen, medium – mobile phosphorus, insufficient – exchange potassium. The weather of the research area characterized by large amplitude of annual fluctuations in air temperature and precipitation. Weather conditions in 2018–2021 differed, both in the amount of precipitation and in the temperature regime. Studies were carried out in order to identify the physiological features of grain harvest formation during pre-sowing treatment of winter wheat seeds with multifunctional preparations on ordinary black soil of the Central Caucasus. To achieve this goal, the chlorophyll content in the organs of winter wheat plants was studied by extracting pigments with 96 % ethyl alcohol, nitrogen content in plants, account­ing for yield and studying the structure of the crop. It was found that pre-sowing treatment of winter wheat seeds with multifunctional preparations contributed to an increase in the concentration of photosynthetic pigments in plant organs by 4.3–17.9 %, and also influenced the consumption of mineral elements, increasing the nitrogen content in plants by an average of 15.6–42 %, depending on the phase of wheat development, which ultimately led to an increase in yield by 0.22–0.37 t/ha. The cost of preparations used for pre-sowing treatment of winter wheat seeds increased production costs by 167–349 rubles /ha, but due to the resulting crop increase, profit increased by 3099–4905 rubles /t, and the profitability of grain production by 9.2–14.1%.

Climatic Trends of Variable Temperate Environment: A Complete Time Series Analysis during 1980–2020

The western Himalayan region is susceptible to minor climate changes because of its fragile ecology, which might threaten the valley’s prestigious ecosystems and socio-economic components. The Himalayas’s local climate and weather are vulnerable to and interlinked with world-scale climatic changes since the region’s hydrology is predominantly dominated by snow and glaciers. The Himalayas, notably the Jammu and Kashmir region in the western Himalayas, has clearly shown distinct and robust evidence of climate change. This study used observed data to examine the climatic variability and trends of change in precipitation and temperature for the Kashmir valley between 1980 and 2020. Gulmarg, Pahalgam, Kokernag, Qazigund, Kupwara, and Srinagar (Shalimar) meteorological stations in the Kashmir valley were studied in detail for long- and short-term as well as localized fluctuations in temperature and precipitation. The annual temperature and precipitation fluctuations were calculated using Sen’s slope approach, and the sloping trend was determined using linear regression. The research showed statistically insignificant growing trends in maximum and minimum temperatures throughout the Kashmir valley. The average annual temperature in the Kashmir valley increased by 1.55 °C during the last 41 years (from 1980 to 2020), with a higher rise in maximum and minimum temperature by 2.00 and 1.10 °C, respectively. However, precipitation showed a non-significant decreasing trend concerning time series analysis over 1980 to 2020 in Kashmir valley. Results of annual average maximum temperature at all the stations revealed that Pahalgam (2.2 °C), Kokernag (1.8 °C), and Kupwara (1.8 °C) displayed a steep upsurge and statistically significant trends; however, annual average minimum temperature followed an increasing trend from 1980 to 2020 at all the stations except Shalimar. However, non-significant declining trends in precipitation were recorded at all the locations in Kashmir valley. This changing pattern of temperature and precipitation could have significant environmental consequences, affecting the western Himalayan region’s food security and ecological sustainability.

Maximum critical temperature and oxygen consumption during thermoregulation in Macrobrachium americanum (Bate, 1868) adult prawns

Macrobrachium americanum is a large prawn living in rivers and coastal water bodies of tropical and subtropical ecosystems of the Pacific side of the Americas. Water temperature and salinity are the main physicochemical variables determining its distribution. Temperature also influences its metabolic rate, which determines growth rate and reproduction. Because of this, preferred temperature, critical thermal maximum (CTMax), and O2 consumption rates at four temperatures (20, 24, 28, and 32°C) were tested from wild prawns in laboratory assays. Those temperatures correspond to the annual temperature fluctuations at the sampling site. The final preferred temperature of this species is close to 26.4°C. The acclimatization temperature has an almost linear effect on the CTMax (R2 = 0.987, P < 0.05), and the oxygen consumption routine rates increased as the acclimation temperature increased from 20 to 32°C.

Calculation of the Fourier criterion in predicting the thermal regime of thawed and frozen dispersed rocks

The purpose of this work was to determine the range of changes in the Fourier criterion (number) when predicting the thermal regime of dispersed rocks in thawed and frozen state. And, also an assessment of the possibility of averaging the thermophysical characteristics of rocks to obtain universal values of Fourier numbers. To achieve this goal, an assessment of the influence of the thermophysical properties of dispersed rocks on the range of changes in the values of the Fourier number used in thermal calculations of technical objects of the cryolithozone is made. The calculation formulas took into account the functional dependence of the coefficient of thermal conductivity, density and specific heat capacity of rocks on humidity (iciness) in the thawed and frozen state. As an example, a mixture of quartz sandstone with water in a thawed and frozen state is considered when the ice content changes from zero (dry quartz sandstone) to full moisture saturation. It is established that the range and nature of the change in Fourier numbers for thawed and frozen dispersed rocks, depending on their humidity (iciness), differs significantly, not only quantitatively, but also qualitatively: for thawed dispersed rocks, the Fourier number decreases with increasing humidity, and for frozen rocks increases. The possibility of averaging the thermophysical characteristics of rocks to obtain universal values of Fourier numbers has been evaluated. It is shown that the use of universal Fourier numbers leads to a significant error for both thawed and frozen rocks and their use in thermal calculations with annual temperature fluctuations is impractical.

Spatio-temporal Trend Determination of Temperature and Rainfall for Climate Change and Variability in Assam State, India

The effect of climate change differs significantly from region to region and it becomes pertinent to ascertain whether the characteristics of major components such as temperature and rainfall have been changing on the regional scale too. In this context, the present study mainly aims to investigate whether there are spatio-temporal changes in temperature and rainfall in Assam and if so, to what extent these changes have been happening. Both parametric and non-parametric methods have been used to study climate change and variability. The study finds that there is a significant increase in annual minimum temperature than the annual maximum temperature in Assam. The fluctuations in annual minimum temperature as shown by the coefficient of variation are also more than the annual maximum temperature. Though the rainfall trend is not significant, the decreasing trend of rainfall in most of the stations during the monsoon season prevails in Assam.

Investigating the climate-adaptive design strategies of residential earth-sheltered buildings in Iran

PurposeThe earth-sheltered building is an adaptive strategy reducing energy consumption as well as increasing thermal comfort of the residents. Although this idea historically implemented in the city of Yazd, Iran, its effects on thermal comfort have not been studied thoroughly. This paper aims to discuss and analyze energy performance, in terms of parameters such as orientation, underground depth, nocturnal ventilation and its subsequent effects on thermal comfort in earth-sheltered buildings in Yazd.Design/methodology/approachUsing EnergyPlus software, the obtained numeric data are precisely modeled, simulated and analyzed.FindingsResults show that there is a direct relationship between depth of construction and energy consumption savings. The more construction depth of earth-sheltered buildings, the more percentage of energy consumption savings, that is of a higher rate in comparison to the aboveground ones. However, in south orientation, energy saving significantly reduces from depth of 2 m downwards and the annual indoor temperature fluctuation decreases by 50%. This subsequently yields to experiencing indoor thermal comfort for a significant number of days throughout the year. Considering the effects of orientation factor, the south orientation regardless of the depth provides the most desired outcome regarding energy savings.Originality/valueSimulating the model generalized to the sunken courtyard can approve that the results of this research can be applied to the other models.

Distributions and sources of isoprenoidal GDGTs in Lake Lugano and other central European (peri-)alpine lakes: Lessons for their use as paleotemperature proxies

Isoprenoidal glycerol dialkyl glycerol tetraether (isoGDGT) lipids occur ubiquitously in freshwater and marine environments. Since their distribution varies with temperature, sedimentary isoGDGTs have been used as proxies for the reconstruction of past continental climate for almost two decades. Yet, their application in lacustrine sediments is still not well constrained because the niches of isoGDGT-producing microorganisms in lakes are often ill-defined. Here, we study the distribution of isoGDGTs and their hydroxy derivatives (OH-isoGDGTs) in the water column of the deep (288 m), meromictic northern basin of Lake Lugano (Switzerland) using quantitative analysis of various pools of isoGDGTs and the stable carbon isotopic composition of isoGDGT-derived biphytanes. We provide strong evidence for archaeal water column sources of the isoGDGTs, based on comparison of lipid data with microbial diversity determined by 16S rRNA next generation sequencing. We find highest concentrations (i.e., 40 ng L−1) of crenarchaeol, the isoGDGTs specific for thaumarchaea, in suspended particle matter (SPM) from deeper (30–100 m) waters below the thermocline. This correlates well with thaumarchaeal 16S rRNA gene abundances, comprised by a single thaumarchaeote of the order Nitrosopumilales. The concentrations of OH-isoGDGT with 0–2 cyclopentane rings follow this profile, suggesting an identical archaeal source. In the deeper anoxic waters, the archaeal community changes substantially and was comprised of various members of the Bathyarchaeota, Diapherotrites, Euryarchaeota, and Woesearchaeota. This change is accompanied by a changing distribution of isoGDGTs with a high contribution of GDGT-0 with a polar head group, and a more negative δ13C value of the acyclic biphytane derived thereof. Comparison of the isoGDGT composition (distribution and δ13C) in the surface sediment with that of the sinking particle flux studied over 1 year at three depths indicates substantial downward transport of isoGDGTs to the sediments from the waters between the thermocline and the anoxic hypolimnion, but not from the deeper (>100 m) waters. The relatively low value for the isoGDGT-based TEX86 value (ca. 0.40) in the surface sediment is similar to that of the in-situ produced isoGDGTs in the waters below the thermocline, and is consistent with the year-around low water temperatures (<6 °C). We also analyzed the isoGDGT composition in surface sediments of 36 additional (peri-)alpine lakes in Central Europe; their isoGDGT concentration and distribution show a clear-cut difference based on lake size. In relatively large and deep lakes, like the Lake Lugano North Basin, the crenarchaeol concentration was much higher than in small-sized and shallow lakes, because Nitrosopumilales spp. have seemingly no niche in shallower waters (0–∼30 m depth), and production, and hence preservation in the sedimentary record, of crenarchaeol (and other thaumarchaeal isoGDGTs) is much lower than in large lakes. We argue that in the mid-latitudinal large and deep (peri-)alpine lakes Nitrosopumilales spp. generally thrive in cold waters below the thermocline, where temperature is largely not affected by fluctuations in mean annual air temperature. Therefore, the TEX86 paleothermometer is relative insensitive to atmospheric temperature changes in these lakes. In the small-sized and shallow lakes and ponds crenarchaeol can still be present but is probably mainly derived from Nitrososphaerales spp. (either from in-situ production or soil erosion). These thaumarchaea are characterized by a higher relative content of the crenarchaeol isomer than the Nitrosopumilales spp. at the same temperature, which may compromise accurate paleotemperature estimations using the TEX86 for small/shallow lakes.

Summer Oxygen Dynamics on a Southern Arabian Gulf Coral Reef

During the summer the Arabian Gulf is the world's warmest sea, also characterized by hypersalinity and extreme annual temperature fluctuations (12–35oC), making it marginal for coral growth. Yet extensive reefs occur in all eight nations bordering the Gulf. Here we present data demonstrating recurrent summer hypoxia events [oxygen concentration (O2) &amp;lt;2 mg l−1] at a reef in the southern Gulf. Currently these episodes are short enough (median 3 h, max 10 h) to preclude mass mortality. Will this always be the case? Predicting future Gulf hypoxia risk for coral reef ecosystems requires diagnosing the underlying causes driving the timing and magnitude of O2 swings. To this end, we compare our data with the output of a simple coupled 1-D water column/biogeochemical model of the reef environment. This allows us to give quantitative estimates of the O2 fluxes produced by photosynthesis both in the water column and within the coral framework, by respiration processes in the benthos, and from the atmosphere. We demonstrate the role of turbulent mixing, and in particular of tides, in shaping the temporal variability of the amplitude of the diel O2 cycle. We find that, in spite of significant turbulent mixing, which maintains the temperature vertically well-mixed, the biological O2 production and consumption is dominant over the atmospheric O2 flux, and is sufficient to generate vertical differences of 1 to 5 mg l−1 between the bottom and 1.5 m above it. While estimating future trends of hypoxia frequency will require further study, the present findings single out the relevant physical and biological processes (and their interplay) which deserve further scrutiny. The Gulf today experiences temperatures expected to occur across much of the tropics by the end of the century, and the observation of recurrent hypoxia events in the Gulf suggests that similar hypoxic phenomena may represent an important, but to date underappreciated, threat to the future of global coral reefs.

Plant Hardiness Zone Map in Korea and an Analysis of the Distribution of Evergreen Trees in Zone 7b

Background and objective This study was conducted to establish a Plant Hardiness Zone (PHZ) map, investigate the effect of global warming on changes in PHZ, and elucidate the difference in the distribution of evergreen trees between the central and southern region within hardiness Zone 7b in Korea. Methods Mean annual extreme minimum temperature (EMT) and related temperature fluctuation data for 40 years (1981 to 2020) in each of the meteorological observation points were extracted from the Open MET Data Portal of the Korea Meteorological Administration. Using EMT data from 60 meteorological observation points, PHZs were classified according to temperature range in the USDA Plant Hardiness Zone Map. Changes in PHZs for each decade related to the effects of global warming were analyzed. Temperature fluctuation before and after the day of EMT were analyzed for 4 areas of Seoul, Suwon, Suncheon, and Jinju falling under Zone 7b. For statistical analysis, descriptive statistics and ANOVA were performed using the IBM SPSS 22 Statistics software package. Results Plant hardiness zones in Korea ranged from 6a to 9b. Over four decades, changes to warmer PHZ occurred in 10 areas, especially in colder ones. Based on the analysis of daily temperature fluctuation, the duration of sub-zero temperatures was at least 2 days in Seoul and Suwon, while daily maximum temperatures were above zero in Suncheon and Jinju before and after EMT day. Conclusion It was found that the duration of sub-zero temperatures in a given area is an important factor affecting the distribution of evergreen trees in PHZ 7b.