Spatiotemporal characterization of heatwave exposure across historically vulnerable communities.

Heatwaves pose a serious threat and are projected to amplify with changing climate and social demographics. A comprehensive understanding of heatwave exposure to the communities is imperative for the development of effective strategies and mitigation plans. This study explores spatiotemporal characterization of heatwaves across the historically vulnerable communities in Mississippi, United States. We derive multiple heatwave metrics including frequency, duration, and magnitude based on temperature data for urban-specific daytime, nighttime, and day-night combined conditions. Our analysis depicts a rising heatwave trend across all counties, with the most extreme shifts observed in prolonged day-night events lacking overnight relief. We integrate physical heatwave hazards with a socioeconomic vulnerability index to develop an integrated urban heatwave risk index. Integrated metric identifies the counties in northwest Mississippi as heat-prone areas, exhibiting an urgent need to prioritize heat resilience and adaptive strategies in these regions. The compounding urban heatwave and vulnerability risks in these communities highlights an environmental justice imperative to implement equitable policies that protect disadvantaged populations. Although this study is focused on Mississippi, our framework is scalable and can be employed to urban regions globally. This study provides a solid foundation for developing timely heatwave preparedness and mitigation to avert preventable heat-related tragedies as extremes intensify with climate change.

The ocean losing its breath under the heatwaves.

The world's oceans are under threat from the prevalence of heatwaves caused by climate change. Despite this, there is a lack of understanding regarding their impact on seawater oxygen levels - a crucial element in sustaining biological survival. Here, we find that heatwaves can trigger low-oxygen extreme events, thereby amplifying the signal of deoxygenation. By utilizing in situ observations and state-of-the-art climate model simulations, we provide a global assessment of the relationship between the two types of extreme events in the surface ocean (0-10 m). Our results show compelling evidence of a remarkable surge in the co-occurrence of marine heatwaves and low-oxygen extreme events. Hotspots of these concurrent stressors are identified in the study, indicating that this intensification is more pronounced in high-biomass regions than in those with relatively low biomass. The rise in the compound events is primarily attributable to long-term warming primarily induced by anthropogenic forcing, in tandem with natural internal variability modulating their spatial distribution. Our findings suggest the ocean is losing its breath under the influence of heatwaves, potentially experiencing more severe damage than previously anticipated.

Deep Learning Models for Health-Driven Forecasting of Indoor Temperatures in Heat Waves in Canada: An Exploratory Study Using Smart Thermostats.

In Canada, extreme heat occurrences present significant risks to public health, particularly for vulnerable groups like older individuals and those with pre-existing health conditions. Accurately predicting indoor temperatures during these events is crucial for informing public health strategies and mitigating the adverse impacts of extreme heat. While current systems rely on outdoor temperature data, incorporating real-time indoor temperature estimations can significantly enhance decision-making and strengthen overall health system responses. Sensor-based technologies, such as ecobee smart thermostats installed in homes, enable effortless collection of indoor temperature and humidity data. This study evaluates the efficacy of deep learning models in predicting indoor temperatures during heat waves using smart thermostat data, to enhance public health responses. Utilizing ecobee smart thermostats, we analyzed indoor temperature trends and developed forecasting models. Our findings indicate the potential of integrating IoT and deep learning into health warning systems, enabling proactive interventions, and improving sustainable health care practices in extreme heat scenarios. This approach highlights the role of digital health innovations in creating the resilient and sustainable healthcare systems against climate-related health adversities.

Marine heatwave-driven mass mortality and microbial community reorganisation in an ecologically important temperate sponge.

Marine heatwaves (MHWs) are increasing in frequency, duration and intensity, disrupting global marine ecosystems. While most reported impacts have been in tropical areas, New Zealand experienced its strongest and longest MHW in 2022, profoundly affecting marine sponges. Sponges are vital to rocky benthic marine communities, with their abundance influencing ecosystem functioning. This study examines the impact of this MHW on the photosynthetic sponge Cymbastella lamellata in Fiordland, New Zealand. We describe the extent, physiological responses, mortality, microbial community changes and ecological impact of this MHW on C. lamellata. The Fiordland MHW reached a maximum temperature of 4.4°C above average, lasting for 259 days. Bleaching occurred in >90% of the C. lamellata Fiordland population. The population size exceeded 66 million from 5 to 25 m, making this the largest bleaching event of its kind ever recorded. We identified the photosynthetic symbiont as a diatom, and bleached sponges had reduced photosynthetic efficiency. Post-MHW surveys in 2023 found that over 50% of sponges at sampling sites had died but that the remaining sponges had mostly recovered from earlier bleaching. Using a simulated MHW experiment, we found that temperature stress was a driver of necrosis rather than bleaching, despite necrosis only rarely being observed in the field (<2% of sponges). This suggests that bleaching may not be the cause of the mortality directly. We also identified a microbial community shift in surviving sponges, which we propose represents a microbial-mediated adaptive response to MHWs. We also found that C. lamellata are key contributors of dissolved organic carbon to the water column, with their loss likely impacting ecosystem function. We demonstrate the potential for MHWs to disrupt key marine phyla in temperate regions, highlighting how susceptible temperate sponges globally might be to MHWs.

Zooplankton responses to simulated marine heatwave in the Mediterranean Sea using in situ mesocosms.

Globally, marine heatwave frequency, intensity, and duration are on the rise, posing a significant threat to plankton communities, the foundational elements of the marine food web. This study investigates the ecological and physiological responses of a temperate plankton community in the Thau lagoon, north-western Mediterranean, to a simulated +3°C ten-day heatwave followed by a ten-day post-heatwave period in in-situ mesocosms. Our analyses encompassed zooplankton grazing, production, community composition in water and sediment traps, as well as oxidative stress and anti-oxidant biomarkers. The results revealed increased abundances of harpacticoid copepods and polychaete larvae during the simulated heatwave and post-heatwave event. Sediment trap data indicated elevated mortality, particularly dominated by polychaete larvae during the post-heatwave period. Oxidative stress biomarker (lipid peroxidation LPX) levels in the plankton community correlated with temperature, signaling cellular damage during the heatwave. LPX increased and proteins decreased with increasing salinity during the experiment. Offspring production peaked during the post-heatwave phase. Notably, the calanoid copepod Acartia clausi exhibited a preference for ciliates as its primary prey, constituting 20% of the overall available prey. Our findings suggest a potential shift in coastal zooplankton communities during future marine heatwaves, transitioning from calanoid mesozooplankton dominance to a system featuring meroplankton and/or harpacticoid copepods. Although species preying on microzooplankton may gain advantages in such conditions, the study underscores the damaging impact of heatwaves on organismal lipids, with potential consequences for reproduction, growth, and survival within marine ecosystems.

Climate Change and Congenital Anomalies: A Population-Based Study of the Effect of Prolonged Extreme Heat Exposure on the Risk of Neural Tube Defects in France.

BACKGROUND: Exposure to long-lasting extreme ambient temperatures in the periconceptional or early pregnancy period might increase the risk of neural tube defects (NTDs). We tested whether prolonged severe heat exposure as experienced during the 2003 extreme heatwave in France, affected the risk of NTDs. METHODS: We retrieved NTD cases spanning from January 1994 to December 2018 from the Paris Registry of Congenital Malformations. The 2003 heatwave was characterized by the long duration and high intensity of nine consecutive days with temperatures ≥35°C. We classified monthly conceptions occurring in August 2003 as "exposed" to prolonged extreme heat around conception (i.e., periconceptional period). We assessed whether the risk of NTDs among cohorts exposed to the prolonged severe heatwave of 2003 in the periconceptional period differed from expected values using Poisson/negative binomial regression. FINDINGS: We identified 1272 NTD cases from January 1994 to December 2018, yielding a monthly mean count of 4.24. Ten NTD cases occurred among births conceived in August 2003. The risk of NTD was increased in the cohort with periconceptional exposure to the August 2003 heatwave (relative risk = 2.14, 95% confidence interval: 1.46 to 3.13), compared to non-exposed cohorts. Sensitivity analyses excluding July and September months or restricting to summer months yielded consistent findings. INTERPRETATION: Evidence from the "natural experiment" of an extreme climate event suggests an elevated risk of NTDs following exposure to prolonged extreme heat during the periconceptional period.

Responding to the Heat and Planning for the Future: An Interview-Based Inquiry of People with Schizophrenia Who Experienced the 2021 Heat Dome in Canada.

People with schizophrenia have died at disproportionately higher rates during recent extreme heat events (EHEs) in Canada, including the deadly 2021 Heat Dome in British Columbia (B.C.). However, to date, little research has qualitatively focused on how people with schizophrenia experience and respond to EHEs. This study aimed to (i) explore how people with schizophrenia experienced and were impacted by the 2021 Heat Dome physically, cognitively, and emotionally and (ii) understand their level of awareness and health-protective actions taken in response to the EHE. Between October 2023 and February 2024, interviews were conducted with 35 people with schizophrenia who experienced the 2021 Heat Dome in a community setting within B.C., Canada. The semi-structured interviews were guided by pre-defined questions to explore the participant's background, living situation, social network, awareness and access to heat-mitigation measures. The transcripts were analyzed using a descriptive form of thematic analysis. Participants shared critical insights on how the EHE impacted them, including descriptions of mild to severe physical manifestations of heat stress (e.g., fainting, heat rashes), the triggering of schizophrenia-related symptoms (e.g., paranoia, hallucinations), and the detrimental effects on their energy levels and emotional stability, which further caused disruptions to their everyday life. Participants also illustrated gaps in knowledge and challenges experienced with accessing information, which hindered their ability to manage the heat exposure effectively and, for some, resulted in no actions (or counter-intuitive actions) being taken to mitigate the heat. These findings demonstrate the complex ways that individuals with schizophrenia experienced and responded to the 2021 Heat Dome and revealed various situational and contextual factors that further compounded the challenge of heat mitigation. These findings can support the development of tailored individual and community-level heat response and communication initiatives and strategies for people with schizophrenia.

Health system adaptations for extreme heat: Protocol for an international scoping review of reviews.

OBJECTIVE: The objective of this study is to map the international evidence for extreme heat related adaptation strategies by health systems, with a particular focus on how heat-vulnerable populations and local situational awareness are considered in these strategies. INTRODUCTION: Since the Paris Climate Accords in 2015, awareness has increased of the health risks posed by extreme heat along with interest in adaptations which aim to reduce heat-health-risks for vulnerable populations. However, the extant literature on these adaptations suggest they are insufficient, and call for research to examine whether, how, and what adaptations for extreme heat are effective as public health interventions. INCLUSION CRITERIA: We will include English-language review articles describing and/or evaluating health system adaptations for extreme heat. Health systems will be defined broadly using the WHO Building Blocks model [1] and adaptations will range from the individual level to institutional, regional and national levels, with particular attention to localisation and the protection of vulnerable individuals. METHODS: A comprehensive literature search of the published literature will be conducted using MEDLINE, Embase, CINAHL, the Cochrane Library and Web of Science. Searches will be limited to reviews published since 2015 in the English language. Results will be exported to EndNote for screening (with a sample checked by two reviewers to ensure consistency). A complementary search for related reports by major international agencies (e.g. WHO; International Association of Emergency Managers), as well as local searches for current guidance and case studies, will be conducted in parallel. Data from included papers will be presented in tables with a narrative commentary.

Marine heatwaves alter competition between the cultured macroalga Gracilariopsis lemaneiformis and the harmful bloom alga Skeletonema costatum.

Seaweed cultivation can inhibit the occurrence of red tides. However, how seaweed aquaculture interactions with harmful algal blooms will be affected by the increasing occurrence and intensity of marine heatwaves (MHWs) is unknown. In this study, we run both monoculture and coculture systems to investigate the effects of a simulated heatwave on the competition of the economically important macroalga Gracilariopsis lemaneiformis against the harmful bloom diatom Skeletonema costatum. Coculture with G. lemaneiformis led to a growth decrease in S. costatum. Growth and photosynthetic activity (Fv/Fm) of G. lemaneiformis was greatly reduced by the heatwave treatment, and did not recover even after one week. Growth and photosynthetic activity of S. costatum was also reduced by the heatwave in coculture, but returned to normal during the recovery period. S. costatum also responded to the stressful environment by forming aggregates. Metabolomic analysis suggests that the negative effects on S. costatum were related to an allelochemical release from G. lemaneiformis. These findings show that MHWs may enhance the competitive advantages of S. costatum against G. lemaneiformis, leading to more severe harmful algal blooms in future extreme weather scenarios.

Responses at various levels of ecological hierarchy indicate acclimation to sequential sublethal heatwaves in a temperate benthic ecosystem.

Marine heatwaves have caused massive mortality in coastal benthic ecosystems, altering community composition. Here, we aim to understand the effects of single and sequential sublethal heatwaves in a temperate benthic ecosystem, investigating their disturbance on various levels of ecological hierarchy, i.e. individual physiology, trophic groups' biomass and ecosystem carbon fluxes. To do so, we performed a near-natural experiment using outdoor benthic mesocosms along spring/summer, where communities were exposed to different thermal regimes: without heatwaves (0HW), with one heatwave (1HW) and with three heatwaves (3HWs). Gastropods were negatively impacted by one single heatwave treatment, but the exposure to three sequential heatwaves caused no response, indicating ecological stress memory. The magnitude of ecosystem carbon fluxes mostly decreased after 1HW, with a marked negative impact on mesograzers' feeding, while the overall intensity of carbon fluxes increased after 3HWs. Consumers' acclimation after the exposure to sequential heatwaves increased grazing activity, representing a threat for the macroalgae biomass. The evaluation of physiological responses and ecological interactions is crucial to interpret variations in community composition and to detect early signs of stress. Our results reveal the spread of heatwave effects along the ecological hierarchical levels, helping to predict the trajectories of ecosystem development.This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Metabolic dysfunctions in pearl oysters following recurrent marine heatwaves.

Marine heatwaves (MHWs) have become more frequent, intense and extreme in oceanic systems in the past decade, resulting in mass mortality events of marine invertebrates and devastating coastal marine ecosystems. While metabolic homeostasis is a fundamental requirement in stress tolerance, little is known about its role under intensifying MHWs conditions. Here, we investigated impacts of MHWs on the metabolism in pearl oysters (Pinctada maxima) - an ecologically and economically significant bivalve species in tropical ecosystems. Activities of digestive enzymes (gastric proteases, lipases, and amylases) did not significantly respond to various scenario of recurrent MHWs varying from 24 °C to 28 °C (moderate) and 32 °C (severe). The metabolomics analysis revealed nine and five key metabolism pathways under both MHWs scenarios. Specifically, pathways associated with energy metabolism were impaired by moderate MHWs, manifesting in downregulation of differential metabolite (The nicotinic acid and N-acetyl-glutamic acid). The content of CDP-ethanolamine was significantly decrease, and the perturbations of oxidative stress caused by the decreased of content of D-glutamine. Metabolites related to a suite of body functions (e.g., the lipid metabolism, biomineralization, and antioxidant defenses) showed significantly negative responses by severe MHWs. These findings reveal the metabolic impairments of marine bivalves when subjected to MHWs varying in intensity and frequency, implying cascading consequences which deserve further investigation.

Unveiling community adaptations to extreme heat events using mobile phone location data.

The escalating frequency, duration, and intensity of extreme heat events have posed a significant threat to human society in recent decades. Understanding the dynamic patterns of human mobility under extreme heat will contribute to accurately assessing the risk of extreme heat exposure. This study leverages an emerging geospatial data source, anonymous cell phone location data, to investigate how people in different communities adapt travel behaviors responding to extreme heat events. Taking the Greater Houston Metropolitan Area as an example, we develop two indices, the Mobility Disruption Index (MDI) and the Activity Time Shift Index (ATSI), to quantify diurnal mobility changes and activity time shift patterns at the city and intra-urban scales. The results reveal that human mobility decreases significantly in the daytime of extreme heat events in Houston while the proportion of activity after 8 p.m. is increased, accompanied with a delay in travel time in the evening. Moreover, these mobility-decreasing and activity-delaying effects exhibited substantial spatial heterogeneity across census block groups. Causality analysis using the Geographical Convergent Cross Mapping (GCCM) model combined with correlation analyses indicates that people in areas with a high proportion of minorities and poverty are less able to adopt heat adaptation strategies to avoid the risk of heat exposure. These findings highlight the fact that besides the physical aspect of environmental justice on heat exposure, the inequity lies in the population's capacity and knowledge to adapt to extreme heat. This research is the first of the kind that quantifies multi-level mobility for extreme heat responses, and sheds light on a new facade to plan and implement heat mitigations and adaptation strategies beyond the traditional approaches.

Racial/ethnic disparities in the distribution of heatwave frequency and expected economic losses in the US.

Previous research on social disparities in heat exposure has not examined heatwave frequency or economic damage at the local or neighborhood level. Additionally, most US studies have focused on specific cities or regions, and few national-scale studies encompassing both urban and rural areas have been conducted. These gaps are addressed here by analyzing racial/ethnic disparities in the distribution of annual heatwave frequency and expected economic losses from heatwave occurrence in the contiguous US. Census tract-level data on annualized heatwave frequency and expected loss from the FEMA's National Risk Index are linked to relevant variables from the American Community Survey. Results indicate that all racial/ethnic minority groups except non-Hispanic Black are significantly overrepresented in neighborhoods with greater annual heatwave frequency (top 10% nationally), and all minority groups are overrepresented in neighborhoods with greater total expected annual loss from heatwaves, compared to non-Hispanic Whites. Multivariable models that control for spatial clustering, climate zone, and relevant socio-demographic factors reveal similar racial/ethnic disparities, and suggest significantly greater heatwave frequency and economic losses in neighborhoods with higher percentages of Hispanics and American Indians. These findings represent an important starting point for more detailed investigations on the adverse impacts of heatwaves for US minority populations and formulating appropriate policy interventions.

Association between ambient temperature and cause-specific mortality: An individual-level case-crossover study in Suzhou, China.

The changing climate poses a growing challenge to the population health. The objective of this study was to assess the association between ambient temperature and cause-specific mortality in Suzhou. Based on the non-accidental mortality data collected during 2008-2022 in Suzhou, China, this study utilized an individual-level case-crossover design to evaluate the associations of temperature with cause-specific mortality. We applied a distributed lag nonlinear model with a maximum lag of 14 days to account for lag effects. Mortality risk due to extreme cold (<2.5th percentile) and extreme heat (>97.5th percentile) was analyzed. A total of 634,530 non-accidental deaths were analyzed in this study. An inverse J-shaped exposure-response relationship was observed between ambient temperature and non-accidental mortality, with the minimum mortality temperature (MMT) at 29.1℃. The relative risk (RR) of mortality associated with extreme cold (2.5th percentile) was 1.37 [95 % confidence interval (CI): 1.30, 1.44], higher than estimate of 1.09 (95 %CI: 1.07, 1.11) for extreme heat (97.5th percentile) relative to the MMT. Heat effect lasted for 2-3 days, while cold effect could persist for almost 14 days. Higher mortality risk estimates were observed for cardiorespiratory deaths compared to total deaths, with statistically significant between-group differences. Consequently, this study provides first-hand evidence on the associations between ambient temperatures and mortality risks from various causes, which could help local government and policy-makers in designing targeted strategies and public health measures against the menace of climate change.

A study on the monitoring of heatwaves and bivariate frequency analysis based on mortality risk assessment in Wuhan, China.

The increasingly frequent occurrence of urban heatwaves has become a significant threat to human health. To quantitatively analyze changes in heatwave characteristics and to investigate the return periods of future heatwaves in Wuhan City, China, this study extracted 9 heatwave definitions and divided them into 3 mortality risk levels to identify and analyze historical observations and future projections of heatwaves. The copula functions were employed to derive the joint distribution of heatwave severity and duration and to analyze the co-occurrence return periods. The results demonstrate the following. (1) As the concentration of greenhouse gas emissions increases, the severity of heatwaves intensifies, and the occurrence of heatwaves increases significantly; moreover, a longer duration of heatwaves correlated with higher risk levels in each emission scenario. (2) Increasing concentrations of greenhouse gas emissions result in significantly shorter heatwave co-occurrence return periods at each level of risk. (3) In the 3 risk levels under each emission scenario, the co-occurrence return periods for heatwaves become longer as heatwave severity intensifies and duration increases. Under the influence of climate change, regional-specific early warning systems for heatwaves are necessary and crucial for policymakers to reduce heat-related mortality risks in the population, especially among vulnerable groups.