Article

Exceedance of wet bulb globe temperature safety thresholds in sports under a warming climate

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Abstract

Extreme heat poses a serious health threat, particularly for people like athletes, soldiers, and workers engaged in outdoor physical activity. For athletes, the American College of Sports Medicine (ACSM) specifies environmental risk categories based on the wet bulb globe temperature (WBGT). We examined the present and future frequency of days that exceed the most extreme ACSM risk category (>32.3 degrees C), when training and practice activities should cease. Using a physically based model, the WBGT was computed for present (1991-2005) climate conditions using standard weather observations and for future (2041-2070) climate conditions using an ensemble of regional climate model output. Results indicate diverse spatial patterns of exceedance across the US in the present-day climate, ranging from <5 d yr(-1) in northern portions of the country to >50 d yr(-1) across portions of the southeastern US and southern Arizona. Under a warming climate, the frequency of days unsuitable for practice sessions according to current ACSM guidelines increases considerably, ranging from 15 to >30 d yr(-1) in broad swaths of the country. Further, our temporal analysis revealed an expansion in the threat for extreme heat through the day ranging from late morning through early evening, although early mornings remain one of the safest periods to avoid heat exposure. Various adaptation strategies such as shifting practice times and developing heat acclimatization plans may be useful in mitigating the impacts of more frequent oppressive days on training sessions.

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... However, what remains unclear for the sport sector, as in many other sectors, is how best to respond (Orr & Inoue, 2019). Further, a systematic understanding of the nature and extent of climate change's impacts on sport is lacking, as the research examining climate change and sport has been disjointed and published in journals as diverse as the disciplines of the researchers, including sport medicine (Nybo et al., 2020), climate research (Grundstein et al., 2013), and tourism . For the latter, Steiger et al. (2019) discussed that research on climate change and ski tourism has reached the diversification phase, where there is a wide array of research questions and interdisciplinary collaborations to understand the impacts of climate change on ski tourism. ...
... Regarding the study locations examined in the reviewed articles, 16 articles (28.6%) examined two or more world regions and were classified into the "multiple locations" category. North America represented the most studied region (n = 13; e.g., Grundstein et al., 2013;. In addition, 10 articles (17.5%) focused on Asian countries, specifically Japan (n = 9; e.g., Gerrett et al., 2019;Olya, 2019; and Qatar (n = 1; Sofotasiou et al., 2015). ...
... | Acknowledgment of climate adaptive measures Most studies (n = 47; 82.5%) acknowledged adaptive measures that have been (or can be) taken by sport entities to respond to the present and future impact of climate change. Only 10 articles did not refer to the climate change adaptation of these entities (e.g., Edgar, 2020;Grundstein et al., 2013). ...
Article
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The relationship between sport and the environment has been primarily examined to understand how sport impacts the natural environment. However, as the influence of climate change has become more apparent, there is a need to establish a systematic understanding of the impacts of climate change on the operations of sport. The aim of this review is to take stock of existing literature on climate change's impacts on organized competitive sport entities, with further attention paid to their adaptation efforts. A scoping review was conducted to identify relevant studies published between 1995 and 2021. After evaluating more than 2100 publications, we retained 57 articles and analyzed them to answer the research questions: (1) What evidence is available regarding the impacts of climate change on the operation of organized competitive sport entities? (2) What is known from the literature about the measures taken by organized competitive sport entities to adapt to the impacts of climate change? Our analysis yielded five major themes: (1) Heat impacts on athlete and spectator health; (2) heat impacts on athlete performance; (3) adaptive measures taken in sport; (4) suitability of various cities for event hosting; and (5) benchmarking and boundary conditions. This review reveals that there is evidence of some climate change impacts on sport, but the literature reflects only a small share of the global sport sector. Equally, much remains to be understood about the nature of adaptation. This article is categorized under: Assessing Impacts of Climate Change > Evaluating Future Impacts of Climate Change
... WBGT is the most comprehensive measurement of heat stress and considered the gold standard. [9][10][11][12] This measure addresses not only ambient temperature and humidity but also wind speed and sun radiation. 9,12,13 However, HI is more commonly used by clinicians than WBGT 14 to determine environmental conditions and suggest exercise modifications. ...
... [9][10][11][12] This measure addresses not only ambient temperature and humidity but also wind speed and sun radiation. 9,12,13 However, HI is more commonly used by clinicians than WBGT 14 to determine environmental conditions and suggest exercise modifications. It can be calculated using several different algorithms 15 but only requires ambient temperature and humidity. ...
... July and August host the hottest temperatures across the country as reported by metrological research. 12 Some YFB events reached environmental conditions as hot as 107°F during these months. Alarmingly, 90.3% of YFB events that took place in late July were in a HIRC that would call for significant activity modification or cancellation. ...
Article
Our study describes youth football (YFB) environmental conditions and the associated heat index (HI) risk category. An observational research design was utilized. Independent variables included month, time, event, and geographic location. Main outcome variables were frequency of events, average HI, and corresponding risk categorization. The HI was recorded with the day and time for each YFB event across 2 YFB seasons. Nearly half (49.8%) of events were in a high HI risk category and 20.0% should have been cancelled. The hottest HI values were recorded in July and August (83.2 ± 9.4°F to 87.2 ± 10.9°F; 24.0% of YFB events). The 7 to 10 am time frame was cooler (67.7 ± 14.5°F; 6.3% of YFB events) than other time frames ( P < .001). Hotter HI values were recorded in practices versus games (75.9 ± 14.1°F vs 70.6 ± 14.6°F; t = -6.426, P < .001). Starting the YFB season in September and holding weekend events in the early morning hours can decrease exposure to environmental heat stress.
... One of the more certain effects of climate change will be increased heat stress in many areas, and several articles made use of the NARCCAP dataset to explore these future conditions [34][35][36][37]. Both Li et al. [36] and Zhou et al. [34] used just one NARCCAP scenario to illustrate methods development, the latter for a sophisticated means of bias correction for some sights in Alabama and the former for establishing relationships between morbidity and heat stress in Milwaukee. ...
... Grundstein et al. [35] examined changes in wet bulb globe temperature (WBGT) throughout the USA, using three NARCCAP scenarios to establish changes in the important threshold event of WBGT>32.3°C when outdoor athletic activity should cease. The physically based model of WBGT used requires inputs of air temperature, relative humidity, wind speed, global solar radiation, and surface pressure. ...
... A number of the impacts calculations were novel and previously unexplored, particularly those that required sophisticated and high-frequency outputs from climate models (e.g., [35,33,39]). This availability of a wide range of highfrequency variables (53 variables at 3-h intervals) was another major reason given by the authors for using the NARCCAP dataset. ...
Article
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We assess the use of the output of the North American Regional Climate Change Assessment Program’s (NARCCAP) regional climate model simulations for future climate impacts and adaptation studies. Over 30 publications have appeared across a wide range of impacts areas, such as hydrology, human health, wild fire risk, and species distributions. The main value of NARCCAP for the impacts researchers was allowing them to explore the effect of the uncertainty of spatial scale of scenarios on their impacts calculations. For example, several studies found that the variability across the higher resolution simulations had as much effect as using output from different global climate models, when applied to their impacts models. We determined the three main reasons the authors used the NARCCAP datasets: the higher spatial resolution (and the assumption of the attendant added value), the availability of many (53) variables at high temporal resolution (3 hourly), and the fact that the dataset was developed for use in impacts studies. This last refers to the issue of confidence in the information being provided based on the motivations and expertise of the providers.
... The infrastructural changes differ based on the hazard, but range from adding shade or fans along the course of a marathon route, to installing outdoor cooling technologies for open-air stadiums, to building brand new facilities [7, p. 9]. Protection against overheating in the SLC territory can include slowing down or pausing for a water break, changing equipment (e.g., to reduce the number of layers worn [15]), or reducing the time for sports, which affects the performance of the athlete. ...
... As an emerging literature, the most consistent thread across the studies is the importance of benchmarking past and current conditions for sport and setting parameters around what is considered safe playing conditions for competition. These parameters, once established through further research centered on the health and safety of players and spectators [15,17], will impact adaptation requirements and innovation [18]. They could also impact the general organizing principles of sport [7, p. 10]. ...
Article
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The climate change that is taking place all around the world today presents challenges for all inhabitants of the planet, including the citizens of Ukraine. Taking all of these circumstances into consideration, it is necessary to introduce new methods of forming the environment that meet the new conditions. The article examines the influence of climate change on the recreational spaces of Ukrainian cities focusing on the location of sports and leisure complexes and their facilities. The article explores the influence of the temperature and humidity of the recreational environment on the athletes' performance and health. The work identifies and systematizes the positive and negative effects of the climate change on a network of sports and leisure complexes and their athletes. The main implication is that outdoor activities can cause heat stress during periods of high ambient temperature. This indicates that the existing sports and leisure complexes are not adapted to climate change. The paper studies the world's practical ways of adapting the urban environment to climate change paying particular attention to a system for alerting the population about the heat waves and informing the citizens about ways to strengthen their immunity; the creation of green and water infrastructure in cities and suburban areas; systems for objective monitoring of diseases and infectious agents affected by climate change, as well as planning for the prevention of these diseases; ensuring the population's access to clean drinking water and monitoring compliance with the technology of disinfection and purification. The study, premised on this analysis, has provided several proposals for adaptive measures implemented while designing a network of sports and leisure complexes in the architectural and urban planning aspects. It is predicted that such measures will help visitors adapt to climate change. It enables us to develop approaches for forming a future network of sports and leisure, taking into consideration cities' changing climatic conditions.
... Grundstein et al. [53] examined the expected frequency of days that exceed the most extreme American College of Sport Medicine risk category (> 32.3 °C WBGT in the US), when training and practice activities are considered to pose a serious health threat. They based their scenario on the A2 IPCC model, a high emission model for 2040-2070. ...
... In states that border the Gulf Coast, > 85 days would have afternoon WBGT > 32.3 °C. The authors also suggested that spring and fall sports (e.g., soccer, football, baseball) would be affected by an expansion of the seasonal range for days exceeding safety thresholds [53]. ...
Article
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Background Climate change impacts are associated with dramatic consequences for human health and threaten physical activity (PA) behaviors.Objective The aims of this systematic review were to present the potential bidirectional associations between climate change impacts and PA behaviors in humans and to propose a synthesis of the literature through a conceptual model of climate change and PA.Methods Studies published before October 2020 were identified through database searches in PubMed, PsycARTICLES, CINAHL, SPORTDiscus, GreenFILE, GeoRef, Scopus, JSTOR and Transportation Research Information Services. Studies examining the associations between PA domains and climate change (e.g., natural disasters, air pollution, and carbon footprint) were included.ResultsA narrative synthesis was performed and the 74 identified articles were classified into 6 topics: air pollution and PA, extreme weather conditions and PA, greenhouse gas emissions and PA, carbon footprint among sport participants, natural disasters and PA and the future of PA and sport practices in a changing world. Then, a conceptual model was proposed to identify the multidimensional associations between climate change and PA as well as sport practices. Results indicated a consistent negative effect of air pollution, extreme temperatures and natural disasters on PA levels. This PA reduction is more severe in adults with chronic diseases, higher body mass index and the elderly. Sport and PA communities can play an important mitigating role in post-natural disaster contexts. However, transport related to sport practices is also a source of greenhouse gas emissions.Conclusion Climate change impacts affect PA at a worldwide scale. PA is observed to play both a mitigation and an amplification role in climate changes.Trial Registration NumberPROSPERO CRD42019128314.
... Grundstein et al. [53] examined the expected frequency of days that exceed the most extreme American College of Sport Medicine risk category (> 32.3 °C WBGT in the US), when training and practice activities are considered to pose a serious health threat. They based their scenario on the A2 IPCC model, a high emission model for 2040-2070. ...
... In states that border the Gulf Coast, > 85 days would have afternoon WBGT > 32.3 °C. The authors also suggested that spring and fall sports (e.g., soccer, football, baseball) would be affected by an expansion of the seasonal range for days exceeding safety thresholds [53]. ...
Preprint
POST PRINT : https://avuer.hypotheses.org/files/2021/05/Bernard-2021-Climate-change-physical-activity-and-sport-a-systematic-review.pdf The climate change manifestations are associated with dramatic consequences for human health and threat physical activity behaviors.Objective The aims of this systematic review were to present the potential bidirectional associations between climate change consequences and physical activity (PA) behaviors in human and to propose the first synthesis of the literature through a conceptual model of climate change and PA. Methods Studies published before October 2019, were identified through database searches in Pubmed, PsycArticles, CINAHL, SportDiscus, GreenFILE and GeoRef. Studies examining the associations between PA domains and climate change (e.g., natural disaster, air pollution, carbon footprint) were included.ResultsA narrative synthesis was performed and the 63 identified articles were classified into 6 topics: air pollution and PA, extreme weather conditions and PA, greenhouse gas emissions and PA, carbon footprint among sport participants, natural disasters and PA and the future of PA and sport practices in a changing world. Then, a conceptual model was proposed to identify the multidimensional associations between climate change and PA as well as sport practices. The results indicated a consistent negative effect of air pollution, extreme temperatures and natural disasters on PA levels. This PA reduction will be more severe in adults with chronic diseases, higher body mass index and elderly. The sport and PA communities can play an important mitigation role in post-natural disaster contexts. However, transport related to sport practices are also a source of greenhouse gas emissions.Conclusion The climate change consequences increasingly and disproportionately impact PA at worldwide scale. PA has two concurrent mitigation and amplification roles towards climate changes.
... Climate change can affect these behaviors, while recreation, exercise, and sport organizations can affect climate change. For example, climate change can affect physical activity behaviors, with heat waves and natural disasters potentially reducing participation in outdoor activities (Grundstein et al., 2013;Scott et al., 2015). An important condition for addressing these issues relates to physical activity behaviors, such as active travel, which can contribute to mitigation efforts by reducing air pollution and greenhouse gas emissions (Wicker, 2019). ...
Chapter
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Man-made global warming is impacting recreation, events, and sports. Climate change affects the viability of outdoor activities, challenging sectors such as event management and sports. Tourism seeks adaptation and resilience in the face of climate change, highlighting the need for local governments to rethink urban areas to attract tourists committed to sustainability. To address this, we explore some sustainable practices and a new and innovative concept-Nature-Based Solutions (NBS). These changes, which are critical to living in harmony with a changing climate, require innovative and sustainable efforts. Key Points • Sporting events are increasingly vulnerable to extreme weather events, requiring climate resilience planning. • Event organizers are prioritizing environmental sustainability and adopting low-carbon initiatives. • Nature-Based Solutions (NbS) offer innovative, cost-effective approaches to address climate challenges. • Collaboration and proactive measures are critical to mitigating the climate impact of leisure and sport.
... Climate change can affect these behaviors, while recreation, exercise, and sport organizations can affect climate change. For example, climate change can affect physical activity behaviors, with heat waves and natural disasters potentially reducing participation in outdoor activities (Grundstein et al., 2013;Scott et al., 2015). An important condition for addressing these issues relates to physical activity behaviors, such as active travel, which can contribute to mitigation efforts by reducing air pollution and greenhouse gas emissions (Wicker, 2019). ...
... adjust work:rest ratios or even cancel activities) will become an increasingly important part of a comprehensive heat safety policy that benefit not only the athletes but help sports medicine and coaching staffs make better informed decisions. [7][8][9][10][11] There are a variety of heat stress indices that range from "direct indices" that are computed from measure environmental variables to "rational indices" that are based on the human heat balance. 12 The focus of this work is on a direct index called the wet bulb globe temperature (WBGT) because it is widely used in sports for heat stress assessment. ...
Article
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The wet bulb globe temperature (WBGT) is widely used in athletics for assessing heat stress. Sports governing bodies provide a wide variety of recommendations on how often to take WBGT measurements during activities like practices and competitions. This can leave coaching staff and other sports medicine personnel in a quandary as to what is the “best practice.” Our study is the first to use a large dataset to quantify the variability of WBGT within practice and competition sessions, and to identify the impact of using different measurement rates on the WBGT. The study leverages 6 years of data from thousands of American football practice and competition sessions from across Georgia, USA. We observed that, on average, WBGTs are coolest in the morning (26.67°C) and evening (24.84°C), and hottest in the midday (30.23°C) and afternoon (27.21°C). The variability within sessions tended to be greater for morning, midday, and afternoon than evenings, with session standard deviations of 0.96°C to 1.27°C and ranges of 2.67°C to 3.55°C when controlling for duration. WBGTs also tended to increase over time in morning sessions and decrease over time during afternoon and evening sessions. These changes are clinically important. We found that Georgia High School Association (GHSA) WBGT activity modification categories often changed during sessions, especially in the morning, midday, and afternoon where a change in GHSA category of ≥1 occurred in 57% to 76% of sessions. Considering this variability, our results indicate that more frequent measurements better capture maximum WBGT values over a session and reduce the likelihood of misclassifying activity modification.
... Selon les divers scénarios d'émissions de gaz à effet de serre, appelés « profils représentatifs d'évolution de concentration » (ou RCP), une augmentation moyenne de la température à la surface de la Terre de 1 à 4 °C est estimée d'ici 2100 (GIEC, 2015), avec de grandes disparités entre les régions. L'humain est et sera donc amené à évoluer dans un environnement de plus en plus chaud (Grundstein et al., 2013;Maloney & Forbes, 2011), y compris au Québec (Ouranos, 2015). Par ailleurs, les enjeux de disponibilité en eau sont de plus en plus présents, en raison de l'accroissement de la demande mondiale, elle-même liée à la forte croissance démographique et à l'élévation du (Bernard et al., 2021). ...
Thesis
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(Thesis written in French) Dehydration, especially when ≥ 2% body mass, is usually associated with an alteration of physiological functions, subjective perceptions as well as endurance performance and cognitive functions. More specifically, it is frequently mentioned that together, the cardiovascular, thermal, metabolic impacts as well as subjective effects induced by dehydration could contribute to increase the perception of effort, which in turn would act as a mediator of endurance performance. While several studies have observed an exacerbation of the perception of effort with dehydration, evidence is contradictory, and some studies do not observe such an effect. In addition, evidence suggests that some individuals may better tolerate dehydration, while others are more widely affected. In this regard, a hypothesis has recently been put forward, according to which repeated exposure to dehydration could somewhat attenuate certain effects, in particular on subjective perceptions, including the perception of effort, and therefore reduce its subsequent impact on performance. In addition to being a possible key mediator in the relationship between exercise-induced dehydration and endurance performance, perception of effort could also play a central role in the process of habituation to the dehydration. However, the idea that humans can become habituated to dehydration has been discussed superficially and anecdotally. Several questions remain unanswered and must therefore be studied.
... Most EMS activations occurred between 11:00 a.m. and 6:59 p.m. This can be explained by not only the ambient air temperatures significantly contributing to convective heat gain but also the sun contributing to short and long wave solar radiation heat gain [44]. The sun is highest in the sky during this time frame as the average time of sunset in the summer is between 7 and 9 p.m. EMS should be prepared for HRI during the summer months, particularly from 11 a.m. to 7 p.m. ...
Article
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Background and objectives: Heat-related illness (HRI) can have significant morbidity and mortality consequences. Research has predominately focused on HRI in the emergency department, yet health care leading up to hospital arrival can impact patient outcomes. Therefore, the purpose of this study was to describe HRI in the prehospital setting. Materials and Methods: A descriptive epidemiological design was utilized using data from the National Emergency Medical Services (EMS) Information System for the 2017–2018 calendar years. Variables of interest in this study were: patient demographics (age, gender, race), US census division, urbanicity, dispatch timestamp, incident disposition, primary provider impression, and regional temperatures. Results: There were 34,814 HRIs reported. The majority of patients were white (n = 10,878, 55.6%), males (n = 21,818, 62.7%), and in the 25 to 64 age group (n = 18,489, 53.1%). Most HRIs occurred in the South Atlantic US census division (n = 11,732, 33.7%), during the summer (n = 23,873, 68.6%), and in urban areas (n = 27,541, 83.5%). The hottest regions were East South Central, West South Central, and South Atlantic, with peak summer temperatures in excess of 30.0 °C. In the spring and summer, most regions had near normal temperatures within 0.5 °C of the long-term mean. EMS dispatch was called for an HRI predominately between the hours of 11:00 a.m.–6:59 p.m. (n = 26,344, 75.7%), with the majority (27,601, 79.3%) of HRIs considered heat exhaustion and requiring the patient to be treated and transported (n = 24,531, 70.5%). Conclusions: All age groups experienced HRI but particularly those 25 to 64 years old. Targeted education to increase public awareness of HRI in this age group may be needed. Region temperature most likely explains why certain divisions of the US have higher HRI frequency. Afternoons in the summer are when EMS agencies should be prepared for HRI activations. EMS units in high HRI frequency US divisions may need to carry additional treatment interventions for all HRI types.
... The need for proactive usage of AMGs based on mathematical models, forecasts, and other data may be further increased in the future to determine event and work cancelations (Hinkson 2017). In some places, there may not be enough "safe" days to conduct physical activity/labor if we follow the current guidelines due to the worsening of extreme heat condition (Grundstein et al. 2013). Additionally, guidelines surrounding cumulative heat stress may be needed as there may be fewer days where individuals are reprieved from high heat in the future (Wallace et al. 2005). ...
Article
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Exertional heat illness (EHI) risk is a serious concern among athletes, laborers, and warfighters. US Governing organizations have established various activity modification guidelines (AMGs) and other risk mitigation plans to help ensure the health and safety of their workers. The extent of metabolic heat production and heat gain that ensue from their work are the core reasons for EHI in the aforementioned population. Therefore, the major focus of AMGs in all settings is to modulate the work intensity and duration with additional modification in adjustable extrinsic risk factors (e.g., clothing, equipment) and intrinsic risk factors (e.g., heat acclimatization, fitness, hydration status). Future studies should continue to integrate more physiological (e.g., valid body fluid balance, internal body temperature) and biometeorological factors (e.g., cumulative heat stress) to the existing heat risk assessment models to reduce the assumptions and limitations in them. Future interagency collaboration to advance heat mitigation plans among physically active population is desired to maximize the existing resources and data to facilitate advancement in AMGs for environmental heat.
... WBGTs in our analysis were obtained from a climatology that covers the period 1991e2005 and includes hourly WBGTs for 217 stations across the contiguous U.S. (Grundstein, Elguindi, Ferrara, & Cooper, 2013;Grundstein, Cooper, Ferrara, & Knox, 2014). The WBGTs were generated from a physically-based WBGT model (Liljegren, Carhart, Lawday, Tschopp, & Sharp, 2008) using meteorological data from airport weather observing stations compiled in the National Solar Radiation Database (NSRDB; National Renewable Energy Laboratory 2007). ...
Article
Increasing temperature will impact future outdoor worker safety but quantifying this impact to develop local adaptations is challenging. Wet bulb globe temperature (WBGT) is the preferred thermal index for regulating outdoor activities in occupational health, athletic, and military settings, but global circulation models (GCMs) have coarse spatiotemporal resolution and do not always provide outputs required to project the full diurnal range of WBGT. This article presents a novel method to project WBGT at local spatial and hourly temporal resolutions without many assumptions inherent in previous research. We calculate sub-daily future WBGT from GCM output and then estimate hourly WBGT based on a site-specific, historical diurnal cycles. We test this method against observations at U.S. Army installations and find results match closely. We then project hourly WBGT at these locations from January 1, 2025, to December 31, 2100, to quantify trends and estimate future periods exceeding outdoor activity modification thresholds. We find regional patterns affecting WBGT, suggesting accurately projecting WBGT demands a localized approach. Results show increased frequency of hours at high WBGT and, using U.S. military heat thresholds, we estimate impacts to future outdoor labor. By mid-century, some locations are projected to average 20 or more days each summer when outdoor labor will be significantly impacted. The method’s fine spatiotemporal resolution enables detailed analysis of WBGT projections, making it useful applied at specific locations of interest.
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This article provides a quantitative analysis of local climate-related factors that may influence the organization of large sport events in Moscow, Russia, and its graphic representation in form of CTIS (Climate-Tourism Information Scheme) with decade resolution for 1991-2021. The individual CTIS for two historical sport events with daily resolution were also done, and then compared to meteorological data recorded during two large sport events to assess the agreement between averaged and actual conditions, which was found to be good enough for CTIS to serve as basic evaluation method. The CTIS-difference with sport events in Moscow compared with cases of Doha and Tokyo seem to be more about identifying the time period with biggest thermal comfort frequencies, instead of looking for occurrences of heat stress conditions. According to 1980 Summer Olympics and 2018 FIFA World Cup events it can be noted that time period was planned satisfactorily. KEYWORDS human thermal comfort heat stress cold stress PET CTIS
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The purpose was to describe wet bulb globe temperature (WBGT) throughout a high school fall athletic season (August to November) after a state-wide mandate requiring schools to use a WBGT-guided activity modification table with categories (AMTC). A cross-sectional research design utilized 30 South Carolina high schools. The independent variables were region (upstate, midlands, and coastal), sport (football, tennis, cross-country), month, start times (7-10 am, 10 am-3 pm, 3-6 pm, and 6-9 pm), and event type (practice, competition). Dependent variables were event frequency, average WBGT, and AMTC. Practice WBGT was 78.7 ± 8.2 °F (range: 34.7 to 99.0 °F). A significant difference for WBGT across month (F6, 904.7 = 385.07, P < 0.001) existed, with early September hotter than all other months (84.8 °F ± 3.8, P < 0.001). Every month had practices in each AMTC, until early November. Most events (64.6%, n = 1986) did not change AMTC; however, 9.1% (n = 281) changed to a hotter category. The 10 am-3 pm start time was significantly hotter than all other time frames (83.0 °F ± 7.2, P < 0.05). Tennis experienced hotter practices (79.9 °F ± 6.9) than football (78.4 °F ± 8.5; P < 0.001) and cross country (78.2 °F ± 8.8, P < 0.001). Schools in the Midlands experienced hotter practices (80.1 °F ± 7.8) than upstate (P < 0.001) and coastal schools (P = 0.005). Competition WBGT was significantly cooler than practices (72.3 ± 10.5 °F, t = 12.04, P < 0.001) and differed across sports (F2, 20.78 = 18.39, P < .001). Both cross-country (P = 0.003) and tennis (P < 0.001) were hotter than football. Schools should continuously monitor WBGT throughout practices and until November to optimize AMTC use. Risk mitigation strategies are needed for sports other than football to decrease the risk of exertional heat illnesses.
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In response to concern for climate change impacting sport competitions and legacies, and the need to consider climate adaptability in event planning, this paper uses a combination of historical weather and air quality data as well as the Intergovernmental Panel on Climate Change Fifth Assessment Report to predict climactic conditions for the mega-events of the 2022 through 2032. In doing so, this paper provides a preliminary overview of environmental conditions (e.g. temperatures, air quality, precipitation) that can be used by event planners to inform contingency plans for the events and their legacies. The most immediate concerns for the mega events between 2022 and 2032 include heat conditions unsuitable for competition and poor air quality, but there may be more harmful environmental concerns for the long-term legacies of these events. It is imperative that event organizers consider creating climate-resilient events, infrastructure, and legacies that can withstand environmental threats in the future.
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Features that are unique to sports participation, such as the timing of the season, use of protective equipment, and prolonged exposure to the sun, make athletes no exception to the risk of extreme heat. In order to attenuate the heat strain imposed on the body during exercise in the heat, heat acclimatization and activity modification guidelines are commonly utilized to enhance the physiological adaptations to the heat and control work-to-rest. Implementation of such guidelines has effectively reduced the numbers of exertional heat stroke fatalities among athletes; however, further research is warranted in establishing policies that account for the ever-increasing threat of climate change and promote the proactive use of weather and climate data to modify athletic activities.
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The North American Regional Climate Change Assessment Program (NARCCAP) is an international effort designed to investigate the uncertainties in regional-scale projections of future climate and produce highresolution climate change scenarios using multiple regional climate models (RCMs) nested within atmosphere–ocean general circulation models (AOGCMs) forced with the Special Report on Emission Scenarios (SRES) A2 scenario, with a common domain covering the conterminous United States, northern Mexico, and most of Canada. The program also includes an evaluation component (phase I) wherein the participating RCMs, with a grid spacing of 50 km, are nested within 25 years of National Centers for Environmental Prediction–Department of Energy (NCEP–DOE) Reanalysis II. This paper provides an overview of evaluations of the phase I domain-wide simulations focusing on monthly and seasonal temperature and precipitation, as well as more detailed investigation of four subregions. The overall quality of the simulations is determined, comparing the model performances with each other as well as with other regional model evaluations over North America. The metrics used herein do differentiate among the models but, as found in previous studies, it is not possible to determine a “best” model among them. The ensemble average of the six models does not perform best for all measures, as has been reported in a number of global climate model studies. The subset ensemble of the two models using spectral nudging is more often successful for domain-wide root-mean-square error (RMSE), especially for temperature. This evaluation phase of NARCCAP will inform later program elements concerning differentially weighting the models for use in producing robust regional probabilities of future climate change.
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(1) We find that elevated greenhouse gas concentrations dramatically increase heat stress risk in the Mediterranean region, with the occurrence of hot extremes increasing by 200 to 500% throughout the region. This heat stress intensification is due to preferential warming of the hot tail of the daily temperature distribution, with 95th percentile maximum and minimum temperature magnitude increasing more than 75th percentile magnitude. This preferential warming of the hot tail is dictated in large part by a surface moisture feedback, with areas of greatest warm-season drying showing the greatest increases in hot temperature extremes. Fine-scale topographic and humidity effects help to further dictate the spatial variability of the heat stress response, with increases in dangerous Heat Index magnified in coastal areas. Further, emissions deceleration substantially mitigates heat stress intensification throughout the Mediterranean region, implying that emissions reductions could reduce the risk of increased heat stress in the coming decades. Citation: Diffenbaugh, N. S., J. S. Pal, F. Giorgi, and X. Gao (2007), Heat stress intensification in the Mediterranean climate change hotspot, Geophys. Res. Lett., 34, L11706, doi:10.1029/2007GL030000.
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"Climate dice," describing the chance of unusually warm or cool seasons, have become more and more "loaded" in the past 30 y, coincident with rapid global warming. The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased. An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (3σ) warmer than the climatology of the 1951-1980 base period. This hot extreme, which covered much less than 1% of Earth's surface during the base period, now typically covers about 10% of the land area. It follows that we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming because their likelihood in the absence of global warming was exceedingly small. We discuss practical implications of this substantial, growing, climate change.
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An important feature of climate change is increasing human heat exposure in workplaces without cooling systems in tropical and subtropical countries. Detailed gridded heat exposure maps will provide essential information for public health authorities. To develop and test methods for calculating occupational heat exposures and present results in easily interpreted maps. Published formulas for a common occupational heat exposure index, the WBGT (Wet Bulb Globe Temperature), were used in combination with global gridded climate data to calculate heat exposure in 0.5° grid squares. Monthly averages of daily maximum temperatures, as indicators of typical temperatures during the hottest part of the day, and corresponding water vapour pressures produced estimates of monthly WBGT indoors (without cooling systems) or outdoors in the shade. The maps show the WBGT within four hot regions of the world during the three hottest months in 1975 and 2000: Australia, South Asia, Southern Africa, Central America, and southern US. Between 1975 and 2000 a WBGT increase of 0.5-1°C was common and the maps show clear decreases in some places. The time trends fit with the development of global climate change. The high WBGT values (particularly in South Asia) already cause excessive occupational heat exposures during the three hottest months. If continued climate change increases WBGT by 3°C, our maps identify areas where occupational heat stress in non-cooled workplaces will be extreme. The mapping method provides a rapid visual impression of occupational heat exposures in large regions of the world. The local changes in WBGT between 1975 and 2000 fit with the global climate change trends. Future increases of WBGT may create extreme heat exposure situations in large areas of the world.
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Thermal stress is an important factor in many industrial situations, athletic events and military scenarios. It can seriously affect the productivity and the health of the individual and diminish tolerance to other environmental hazards. However, the assessment of the thermal stress and the translation of the stress in terms of physiological and psychological strain is complex. For over a century attempts have been made to construct an index, which will describe heat stress satisfactorily. The many indices that have been suggested can be categorized into one of three groups: "rational indices", "empirical indices", or "direct indices". The first 2 groups are sophisticated indices, which integrate environmental and physiological variables; they are difficult to calculate and are not feasible for daily use. The latter group comprises of simple indices, which are based on the measurement of basic environmental variables. In this group 2 indices are in use for over four decades: the "wet-bulb globe temperature" (WBGT) index and the "discomfort index" (DI). The following review summarizes the current knowledge on thermal indices and their correlates to thermal sensation and comfort. With the present knowledge it is suggested to adopt the DI as a universal heat stress index.
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This Policy Statement was revised. See https://doi.org/10.1542/peds.2011-1664 For morphologic and physiologic reasons, exercising children do not adapt as effectively as adults when exposed to a high climatic heat stress. This may affect their performance and well-being, as well as increase the risk for heat-related illness. This policy statement summarizes approaches for the prevention of the detrimental effects of children's activity in hot or humid climates, including the prevention of exercise-induced dehydration.
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We utilize a revised Thornthwaite climate classification system for model intercomparisons and to visualize future climate change. This classification system uses an improved moisture factor that accounts for both evapotranspiration and precipitation, a thermal index based on potential evapotranspiration, and even intervals between categories for ease of interpretation. The use of climate types is a robust way to assess a model’s ability to reproduce mutlivariate conditions. We compare output from multiple regional climate models (RCMs) participating in NARCCAP (North American Regional Climate Change Assessment Program) as well as their coarser driving general circulation models (GCMs). Overall, the RCM ensemble does a good job in reproducing the main features of U.S. climate types. The “added-value” gained by downscaling with RCMs is significant, particularly in topographic regions such as the west coast and Appalachian Mountains. Ensemble model output from the scenario simulations indicates a recession of cold climate zones across the eastern U.S. and northern tier of the country as well as in mountainous areas. Projections also indicate the development of a novel climate zone, the torrid climate, across southern portions of the country. In addition, the U.S. will become drier, particularly across the Midwest as the moisture boundary shifts eastward, and in the the Appalachian region. Climate types in the Pacific Northwest, however, will not change greatly. Finally, we demonstrate possible applications for the forecast climate types and associated output variables.
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Thermal comfort is quantified in 15 regions using the wet-bulb globe temperature (WBGT), examining past and future rates of thresholds exceedance corresponding to moderate, high, and extreme heat (28, 32, and 35 °C, respectively). As recent changes to thermal comfort appear to be dominated by temperature and humidity, a WBGT approximation based only on these is used. A new homogenised dataset from 1973 to 2003 is developed which provides WBGT daily means, daily maximums averaged over 5-day periods, and the highest extreme for each 5-day period; recent trends are positive for all regions except northeast USA and northeast Australia. A simple model for predicting summertime threshold exceedance rates, with a fixed distribution of anomalies about the seasonal mean, is found to adequately predict changes for the above quantities given seasonal mean values. This model is used to predict the impact of regional 1–5 °C temperature increases on WBGT exceedance rates with no change in relative humidity. Results show that heat events may worsen as much, or more, in humid tropical and mid-latitude regions even if they warm less than the global average, due to greater absolute humidity increases. A further 2 °C warming from the present is sufficient to push peak WBGT above 35 °C, an extreme heat event, in all regions except the UK. An ensemble of HadCM3 climate model simulations is used to investigate likely regional changes in mean summertime temperature, relative humidity and WBGT under an A1B scenario for the 2020s and 2050s. Unsurprisingly, simulated regional changes often depart significantly from the global average, and the impact of regional changes in relative humidity is not always negligible. Increases in WBGT are nonetheless expected in all regions, and are more predictable than increases in temperature at least in mid-latitude regions owing to the compensating effects of humidity. © 2010 Royal Meteorological Society and Crown Copyright
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While many factors affecting human health that will alter with climate change are being discussed, there has been no discussion about how a warmer future will affect man's thermoregulation. Using historical climate data for an Australian city and projections for Australia's climate in 2070, we address the issue using heat balance modelling for humans engaged in various levels of activity from rest to manual labour. We first validate two heat balance models against empirical data and then use the models to predict the number of days at present and in 2070 that (1) sweating will be required to attain heat balance, (2) heat balance will not be possible and hyperthermia will develop, and (3) body temperature will increase by 2.5°C in less than 2 h, which we term "dangerous days". The modelling is applied to people in an unacclimatised and an acclimatised state. The modelling shows that, for unacclimatised people, outdoor activity will not be possible on 33-45 days per year, compared to 4-6 days per year at present. For acclimatised people the situation is less dire but leisure activity like golf will be not be possible on 5-14 days per year compared to 1 day in 5 years at present, and manual labour will be dangerous to perform on 15-26 days per year compared to 1 day per year at present. It is obvious that climate change will have important consequences for leisure, economic activity, and health in Australia.
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We evaluated temperature-related morbidity and mortality for the 2007 U.S. national assessment on impacts of climate change and variability on human health. We assessed literature published since the 2000 national assessment, evaluating epidemiologic studies, surveys, and studies projecting future impacts. Under current climate change projections, heat waves and hot weather are likely to increase in frequency, with the overall temperature distribution shifting away from the colder extremes. Vulnerable subgroups include communities in the northeastern and Midwestern U.S.; urban populations, the poor, the elderly, children, and those with impaired health or limited mobility. Temperature extremes and variability will remain important determinants of health in the United States under climate change. Research needs include estimating exposure to temperature extremes; studying nonfatal temperature-related illness; uniform criteria for reporting heat-related health outcomes; and improving effectiveness of urban heat island reduction and extreme weather response plans.
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The U.S. Army has a need for continuous, accurate estimates of the wet bulb globe temperature to protect soldiers and civilian workers from heat-related injuries, including those involved in the storage and destruction of aging chemical munitions at depots across the United States. At these depots, workers must don protective clothing that increases their risk of heat-related injury. Because of the difficulty in making continuous, accurate measurements of wet bulb globe temperature outdoors, the authors have developed a model of the wet bulb globe temperature that relies only on standard meteorological data available at each storage depot for input. The model is composed of separate submodels of the natural wet bulb and globe temperatures that are based on fundamental principles of heat and mass transfer, has no site-dependent parameters, and achieves an accuracy of better than 1 degree C based on comparisons with wet bulb globe temperature measurements at all depots.
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A global coupled climate model shows that there is a distinct geographic pattern to future changes in heat waves. Model results for areas of Europe and North America, associated with the severe heat waves in Chicago in 1995 and Paris in 2003, show that future heat waves in these areas will become more intense, more frequent, and longer lasting in the second half of the 21st century. Observations and the model show that present-day heat waves over Europe and North America coincide with a specific atmospheric circulation pattern that is intensified by ongoing increases in greenhouse gases, indicating that it will produce more severe heat waves in those regions in the future.
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