The rising frequency of extreme heat events poses an escalating threat of heat-related illnesses and fatalities, placing an additional strain on global healthcare systems. Whether the risk of ...heat-related issues is sex specific, particularly among the elderly, remains uncertain.
16 men and 15 women of similar age (69 ± 5 years) were exposed to an air temperature of 39.1 ± 0.3 °C and a relative humidity (RH) of 25.1 ± 1.9%, during 20 min of seated rest and at least 40 min of low-intensity (10 W) cycling exercise. RH was gradually increased by 2% every 5 min starting at minute 30. We measured sweat rate, heart rate, thermal sensation, and the rise in gastrointestinal temperature (Tgi) and skin temperature (Tsk).
Tgi consistently increased from minute 30 to 60, with no significant difference between females and males (0.012 ± 0.004 °C/min vs. 0.011 ± 0.005 °C/min; p = 0.64). Similarly, Tsk increase did not differ between females and males (0.044 ± 0.007 °C/min vs. 0.038 ± 0.011 °C/min; p = 0.07). Females exhibited lower sweat rates than males (0.29 ± 0.06 vs. 0.45 ± 0.14 mg/m
/min; p < 0.001) in particular at relative humidities exceeding 30%. No sex differences in heart rate and thermal sensation were observed.
Elderly females exhibit significantly lower sweat rates than their male counterparts during low-intensity exercise at ambient temperatures of 39 °C when humidity exceeds 30%. However, both elderly males and females demonstrate a comparable rise in core temperature, skin temperature, and mean body temperature, indicating similar health-related risks associated with heat exposure.
Critical environmental limits are those combinations of ambient temperature and humidity above which heat balance cannot be maintained for a given metabolic heat production, limiting exposure time, ...and placing individuals at increased risk of heat-related illness. The aim of this study was to establish those limits in young (18-34 yr) healthy adults during low-intensity activity approximating the metabolic demand of activities of daily living. Twenty-five (12 men/13 women) subjects were exposed to progressive heat stress in an environmental chamber at two rates of metabolic heat production chosen to represent minimal activity (MinAct) or light ambulation (LightAmb). Progressive heat stress was performed with either
) constant dry-bulb temperature (T
) and increasing ambient water vapor pressure (P
) (P
trials; 36°C, 38°C, or 40°C) or
) constant P
and increasing T
(T
trials; 12, 16, or 20 mmHg). Each subject was tested during MinAct and LightAmb in two to three experimental conditions in random order, for a total of four to six trials per participant. Higher metabolic heat production (
< 0.001) during LightAmb compared with MinAct trials resulted in significantly lower critical environmental limits across all P
and T
conditions (all
< 0.001). These data, presented graphically herein on a psychrometric chart, are the first to define critical environmental limits for young adults during activity resembling those of light household tasks or other activities of daily living and can be used to develop guidelines, policy decisions, and evidence-based alert communications to minimize the deleterious impacts of extreme heat events.
Critical environmental limits are those combinations of temperature and humidity above which heat balance cannot be maintained, placing individuals at increased risk of heat-related illness. Those limits have been investigated in young adults during exercise at 30% V̇o
, but not during metabolic rates that approximate those of light activities of daily living. Herein, we establish critical environmental limits for young adults at two metabolic rates that reflect activities of daily living and leisurely walking.
Critical environmental limits are temperature-humidity thresholds above which heat balance cannot be maintained for a given metabolic heat production. This study examined the association between ...individual characteristics sex, body surface area (A
), aerobic capacity (V̇o
), and body mass (m
) and critical environmental limits in young adults at low metabolic rates. Forty-four (20 M/24 F; 23 ± 4 yr) subjects were exposed to progressive heat stress in an environmental chamber at two low net metabolic rates (M
); minimal activity (MinAct; M
= ∼160 W) and light ambulation (LightAmb; M
= ∼260 W). In two hot-dry (HD; ≤25% rh) environments, ambient water vapor pressure (P
= 12 or 16 mmHg) was held constant and dry-bulb temperature (T
) was systematically increased. In two warm-humid (WH; ≥50% rh) environments, T
was held constant at 34°C or 36°C, and P
was systematically increased. The critical wet-bulb globe temperature (WBGT
) was determined for each condition. During MinAct, after entry of M
into the forward stepwise linear regression model, no individual characteristics were entered into the model for WH (
= 0.01,
= 0.27) or HD environments (
= -0.01,
= 0.44). During LightAmb, only m
was entered into the model for WH environments (
= 0.44,
< 0.001), whereas only V̇o
was entered for HD environments (
= 0.22;
= 0.002). These data demonstrate negligible importance of individual characteristics on WBGT
during low-intensity nonweight-bearing (MinAct) activity with a modest impact of m
and V̇o
during weight-bearing (LightAmb) activity in extreme thermal environments.
Our laboratory has recently published a series of papers establishing the upper ambient temperature-humidity thresholds for maintaining heat balance, termed critical environmental limits, in young adults. However, no studies have investigated the relative influence of individual characteristics, such as sex, body size, and aerobic fitness, on those environmental limits. Here, we demonstrate the contributions of sex, body mass, body surface area, and maximal aerobic capacity on critical wet-bulb globe temperature (WBGT) limits in young adults.
In a rapidly changing world, what is today an unprecedented extreme may soon become the norm. As a result, extreme‐related disasters are expected to become more frequent and intense. This will have ...widespread socio‐economic consequences and affect the ability of different societal groups to recover from and adapt to rapidly changing environmental conditions. Therefore, there is the need to decipher the relation between genesis of unprecedented events, accumulation and distribution of risk, and recovery trajectories across different societal groups. Here, we develop an analytical approach to unravel the complexity of future extremes and multiscalar societal responses—from households to national governments and from immediate impacts to longer term recovery. This requires creating new forms of knowledge that integrate analyses of the past—that is, structural causes and political processes of risk accumulation and differentiated recovery trajectories—with plausible scenarios of future environmental extremes grounded in the event‐specific literature. We specifically seek to combine the physical characteristics of the extremes with examinations of how culture, politics, power, and policy visions shape societal responses to unprecedented events, and interpret the events as social‐environmental extremes. This new approach, at the nexus between social and natural sciences, has the concrete advantage of providing an impact‐focused vision of future social‐environmental risks, beyond what is achievable within conventional disciplinary boundaries. In this paper, we focus on extreme flooding events and the societal responses they elicit. However, our approach is flexible and applicable to a wide range of extreme events. We see it as the first building block of a new field of research, allowing for novel and integrated theoretical explanations and forecasting of social‐environmental extremes.
Key Points
We conceptualize unprecedented extremes as social‐environmental processes shaped by institutional, political, and economic change
As social‐environmental extremes become more frequent, there is an urgency to unravel their genesis and the possible societal responses
This approach is the first building block of a new field of research in social‐environmental extreme event forecasts
Plain Language Summary
The world is seeing increases in a range of extreme events, and this increase may continue or even accelerate in the future, due to anthropogenic climate change. Furthermore, it is often those who are already vulnerable that experience the biggest impacts from these extremes. Yet, there is little understanding of the possible societal responses to unprecedented events. This underscores the urgency of creating innovative approaches to develop plausible scenarios of societal responses and, in turn, mitigate hazards and reduce vulnerability and exposure to extreme events. In this commentary, we develop a truly interdisciplinary conceptual approach to better understand how different societal groups might interact with and respond to future unprecedented extreme events. We combine social science theories describing how different societal groups are affected by, and recover from, extreme events with projections from the literature identifying plausible areas at risk of unprecedented occurrences and local analyses of past extreme events. We see this as the first building block of a new field of research in forecasting social‐environmental extremes that could support governments, civil protection agencies, and civil society organizations to ensure a fairer, improved response to future events.
This article describes the effect of extreme water level events and extreme temperatures on the primary productivity and habitus of the common reed (Phragmites australis) growing in lake and riparian ...habitats at intermittent Lake Cerknica between 2007 and 2021. At each sampling site, the above-ground biomass, leaf biomass and shoot density per m2, the number of internodes and leaves per plant, average shoot height, shoot basal diameter and the ratio of flowering plants per total plant number were determined. Stand and plant properties varied significantly between the locations, with exception of the basal diameter, that varied less. Biomass per area and per plant showed the trend of decrease across years, but the reed density remained at the same level. Redundancy analysis of the relationships between environmental parameters and productivity and habitus parameters revealed the importance for the lake stand of high-water level parameters in the 4th quarter of the previous year, while the 1st quarter of the current year was important for the riparian stand. High water level variables explained 60% of variance of productivity parameters of the lake stand and 21% of those of the riparian stand. For low water level parameters, the explained variance was 51 and 24%, respectively. In the case of habitus parameters, variances explained by high water level parameters were 66% for lake stand and 34% for riparian stand and of low water level parameters, the corresponding variances were 45% for lake stand and 59% for riparian stand. Temperature extremes can explain the lower variance. The interrelation between wetland hydrological extremes and reed stand/plant properties that was obtained suggests that an ecohydrological approach may provide a basis for successful management of reed-colonised wetlands.
•Common reed response to extremes differed regarding habitat; lake stand was more affected than riparian stand.•High water strongly affected lake reed production, while low water imposed more effect on riparian reed habitus.•Management of water level extremes may be used to increase the production of native and suppress invasive alien reed.
Space missions of long duration required a series of preliminary experiments on living organisms, validated by a substantial phase of ground simulation experiments, in the field of micro- and ...inter-mediate gravities, radiobiology, and, for planetary explorations, related to risks deriving from regolith and dust exposure. In this review, we present the tardigrades, whose characteristics that recommend them as an emerging model for space biology. They are microscopic animals but are characterized by a complex structural organization similar to that of larger animals; they can be cultured in lab in small facilities, having small size; they are able to produce clonal lineages by means of parthenogenesis; they can completely suspend their metabolism when entering in dormant states (anhydrobiosis induced by dehydration and cryobiosis induced by freezing); desiccated anhydrobiotic tardigrades are able to withstand chemical and physical extremes, but a large tolerance is showed also by active animals; they can be stored in dry state for many years without loss of viability. Tardigrades have already been exposed to space stressors on Low Earth Orbit several times. The relevance of ground-based and space studies on tardigrades rests on the presumption that results could suggest strategies to protect organisms, also humans, when exposed to the space and lunar environments.
► Active and dry tardigrades can withstand extreme conditions. ► Tardigrades are proposed as model organisms for space biology. ► The space missions in which tardigrades have been involved are reported. ► Ground experiments on tardigrades to prepare lunar exploration are proposed.
Brassinosteroids (BRs) are ubiquitous plant steroid hormones, playing diverse roles in plant growth, development and stress responses. Defects in BRs biosynthesis or signaling result in physiologic ...and phenotypic abnormalities. To date, numerous studies have highlighted BRs-induced stress tolerance to various environmental extremes such as high temperature, chilling, drought, salinity and heavy metals in a range of plant species. However, the in-depth mechanisms of BRs-induced stress tolerance still remain largely unknown. It is now clear that BRs-induced stress responses are strictly concentration dependent and the optimal concentration for improving the plant adaptability may vary depending on the plant species, developmental stages and environmental conditions as well. Conflicting evidences concerning regulation of stress adaptation by BRs demand further elucidation of mechanism of BRs action in response to environmental stresses in plants. Recent advances in phytohormone research suggest that the effect of BRs on stress tolerance relies largely on its interplay with other hormones. In this review, we critically analyze the multifaceted roles of BRs in various abiotic stresses and its potential crosstalk with other hormones in stress adaptation. The discrepancy in the dose and mode of application of BRs analogues for stress management is also discussed.
Recent extreme value theory literature has seen significant emphasis on the modelling of spatial extremes, with comparatively little consideration of spatio-temporal extensions. This neglects an ...important feature of extreme events: their evolution over time. Many existing models for the spatial case are limited by the number of locations they can handle; this impedes extension to space–time settings, where models for higher dimensions are required. Moreover, the spatio-temporal models that do exist are restrictive in terms of the range of extremal dependence types they can capture. Recently, conditional approaches for studying multivariate and spatial extremes have been proposed, which enjoy benefits in terms of computational efficiency and an ability to capture both asymptotic dependence and asymptotic independence. We extend this class of models to a spatio-temporal setting, conditioning on the occurrence of an extreme value at a single space–time location. We adopt a composite likelihood approach for inference, which combines information from full likelihoods across multiple space–time conditioning locations. We apply our model to Red Sea surface temperatures, show that it fits well using a range of diagnostic plots, and demonstrate how it can be used to assess the risk of coral bleaching attributed to high water temperatures over consecutive days.
The potential for changes in environmental extremes is routinely investigated by fitting change-permitting extreme value models to long-term observations, allowing one or more distribution parameters ...to change as a function of time or some other covariate. In most extreme value analyses, the main quantity of interest is typically the upper quantiles of the distribution, which are often needed for practical applications such as engineering design. This study focuses on the changes in quantile estimates under different change-permitting models. First, metrics which measure the impact of changes in parameters on changes in quantiles are introduced. The mathematical structure of these change metrics is investigated for several change-permitting models based on the Generalised Extreme Value (GEV) distribution. It is shown that for the most commonly used models, the predicted changes in the quantiles are a non-intuitive function of the distribution parameters, leading to results which are difficult to interpret. Next, it is posited that commonly used change-permitting GEV models do not preserve a constant coefficient of variation, a property that is typically assumed to hold for environmental extremes. To address these shortcomings a new (parsimonious) model is proposed: the model assumes a constant coefficient of variation, allowing the location and scale parameters to change simultaneously. The proposed model results in changes in the quantile function that are easier to interpret. Finally, the consequences of the different modelling choices on quantile estimates are exemplified using a dataset of extreme peak river flow measurements in Massachusetts, USA. It is argued that the decision on which model structure to adopt to describe change in extremes should also take into consideration any requirements on the behaviour of the quantiles of interest.
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