Narrow Results

We present the theory of spacetime elasticity and demonstrate that it involves traditional thermoelasticity. Assuming linear-elastic constitutive behavior and using spacetime transversely-isotropic elastic constants, we derive all principal thermodynamic relations of classical thermoelasticity. We introduce the spacetime principle of virtual work, and use it to derive the equations of motion for both reversible and dissipative thermoelastic dynamics. We show that spacetime elasticity directly implies the Fourier and the Maxwell–Cattaneo laws of heat conduction. However, spacetime elasticity is richer than classical thermoelasticity, and it advocates its own equations of motion for coupled thermoelasticity, complemented by the spectrum of boundary and interface conditions. We argue that the presented framework of spacetime elasticity should prove adequate for describing the thermoelastic phenomena occurring at low temperatures, for interpreting the results of molecular simulations of heat conduction in solids, and also for the optimal heat and stress management in the microelectronic components and the thermoelectric devices.

We derive and analyze the linearized hyperbolic equations describing a relativistic heat-conducting elastic rod. We construct a decreasing energy integral for these equations, compute the associated characteristic propagation speeds and prove that the solutions decay in time by using a Fourier decomposition. For comparison purposes, we obtain analogous results for the classical system with heat waves, in which the finite propagation speed of heat is kept but the other relativistic terms are neglected and also for the usual classical system.

Heat waves, defined as an interval of abnormally hot and humid weather, have become a prominent killer in recent years. With heat waves worsening with climate change, adaptation is essential; one strategy has been to issue heat wave warnings and undertake awareness campaigns to bring about behavioral changes to reduce heat stroke. Since 2002, the Indian state of Odisha has been undertaking a grassroots awareness campaign on "dos and don'ts" during heat wave conditions through the disaster risk management (DRM) program. The selection criteria for DRM districts were earthquake, flood and cyclone incidence; but subsequently, heat wave awareness also received intensive attention in these districts. We present quasi-experimental evidence on the impact of the program, taking DRM districts and periods as treatment units and the rest as controls, analyzing the impact on the death toll from heat stroke for the 1998 to 2010 period, using difference-in-difference (DID) regressions with a district level panel data set and a set of control variables. We find indications of program effectiveness with initial DID specifications, but results are not always robust. We then take into account a statewide heat wave advertising program, to which the poor have limited exposure but which may also provide spillover benefits, using a triple differencing approach; results suggest the heat wave awareness programs may have complementary impacts. We examine research strategies for further improvement in the precision of impact evaluation results for innovative programs of this type.

Heat wave impact on labor supply is less researched, though workers in exposed occupations have been seriously impacted in recent years, especially in developing economies. The paper identifies labor reallocation and coping strategies of poor urban workers on a heat wave day compared to a normal summer day by surveying informal sector workers who work in the open. The workers are found to forgo 1.19 h of work time and 0.46 h of family time and use these extra 1.65 h to rest more on heat wave days to adapt to heat stress. They resort to other adaptations like eating appropriate food with high water content, keeping their house cool by repeated wiping of floor using cooling ingredients, covering the roof of their living space with paddy straw, putting thick grass curtains, using fans for longer hours etc. These adaptations including the work time loss costs around INR 195 per heat wave day to a household, which is, on average, 2.7% of their monthly income. The paper approximates the private adaptation costs of informal sector workers to heat waves.

This study examines how three types of extreme events (heat waves, droughts, floods) are mentioned together with climate change on social media. English-language Twitter use during 2008–2017 is analyzed, based on 1,127,996 tweets (including retweets). Frequencies and spikes of activity are compared and theoretically interpreted as reflecting complex relations between the extreme event factor (the occurrence of an extreme event); the media ecology factor (climate-change oriented statements/actions in the overall media landscape) and the digital action factor (activities on Twitter). Flooding was found to be by far the most tweeted of the three in connection to climate change, followed by droughts and heat waves. It also led when comparing spikes of activity. The dominance of floods is highly prevalent from 2014 onwards, triggered by flooding events (extreme event factor), the climate science controversy in US politics (media ecology factor) and the viral power of celebrities’ tweets (digital action factor).

Extreme heat is a growing concern for cities, with both climate change and the urban heat island (UHI) effect increasingly impacting public health, economies, urban infrastructure, and urban ecology. To better understand the current state of planning for extreme heat, we conducted a systematic literature review. We found that most of the research focuses on UHI mapping and modeling, while few studies delve into extreme heat planning and governance processes. An in-depth review of this literature reveals common institutional, policy, and informational barriers and strategies for overcoming them. Identified challenges include siloed heat governance and research that limit cross-governmental and interdisciplinary collaboration; complex, context-specific, and diverse heat resilience strategies; the need to combine extreme heat “risk management” strategies (focused on preparing and responding to extreme heat events) and “design of the built environment” strategies (spatial planning and design interventions that intentionally reduce urban temperatures); and the need for extensive, multidisciplinary data and tools that are often not readily available. These challenges point to several avenues for future heat planning research. Ultimately, we argue that planners have an important role to play in building heat resilience and conclude by identifying areas where scholars and practitioners can work together to advance our understanding of extreme heat planning.

Extreme temperatures and high levels of air pollutants pose major risks to human health. Because heat waves and pollution episodes share common underlying drivers, they often coincide; additionally, they may worsen under future climate change and so it is extremely important to understand the extent of their co-occurrence so that proper mitigation and adaptation steps can be taken to minimize their impact. Here, we use 15 years of observations of temperature, and measurements of surface ozone and particulate matter (the two air pollutants with the greatest human health impact) to characterize the overlap of extreme pollution episodes and heat waves. We show that all three extremes occur in large-scale, multi-day, overlapping and coherent structures. Additionally, we find that the largest, longest lasting episodes have the greatest frequency of co-occurring extremes and have the highest temperatures and most extreme levels of pollution.

The unprecedented increase in frequency, intensity, and severity of extreme heat events is one of the most sensitive manifestations of climate change. Unusually, high ambient temperatures have severe societal impacts, driven primarily by excess mortality and morbidity, loss of productivity, etc. Despite these alarming signs of a changing climate, most of us remain inactive, perhaps expecting a high degree of resilience to episodic heat spells. In an effort to understand the effects of extreme heat events on a population normally perceived as immune to elevated temperature, we studied the impacts of indoor temperature on cognitive function among young and healthy college-age students living in air-conditioned (AC) and non-air conditioned spaces (non-AC). We used a high-density array of environmental sensors to characterize residential indoor exposures, and wearable devices to track levels of physical activity, sleep, changes in heart rate, and skin perspiration. In addition, we administered daily color-word and arithmetic tests to assess changes in cognitive function before, during, and after a heat wave. Our study represents the first effort to understand the influence of indoor thermal conditions on cognitive function in a non-experimental setting, capturing the environmental and behavioral context with unequivocal validity. Moreover, the study design mimics an experimental study by comparing the effect between individuals with and without AC, and assuming that any difference between them would have remained constant if the heat wave did not take place. Therefore, the findings would suggest a causal effect of temperature on cognition, and their implications extend to building operational practices, climate preparedness plans, and strategies to retrofit and redesign buildings in a sustainable way.