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Luo M, Wu S, Lau GNC, Pei T, Liu Z, Wang X, Ning G, Chan TO, Yang Y, Zhang W. Anthropogenic forcing has increased the risk of longer-traveling and slower-moving large contiguous heatwaves. SCIENCE ADVANCES 2024; 10:eadl1598. [PMID: 38552023 PMCID: PMC10980275 DOI: 10.1126/sciadv.adl1598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/26/2024] [Indexed: 04/01/2024]
Abstract
Heatwaves are consecutive hot days with devastating impacts on human health and the environment. These events may evolve across both space and time, characterizing a spatiotemporally contiguous propagation pattern that has not been fully understood. Here, we track the spatiotemporally contiguous heatwaves in both reanalysis datasets and model simulations and examine their moving patterns (i.e., moving distance, speed, and direction) in different continents and periods. Substantial changes in contiguous heatwaves have been identified from 1979 to 2020, with longer persistence, longer traveling distance, and slower propagation. These changes have been amplified since 1997, probably due to the weakening of eddy kinetic energy, zonal wind, and anthropogenic forcing. The results suggest that longer-lived, longer-traveling, and slower-moving contiguous heatwaves will cause more devastating impacts on human health and the environment in the future if greenhouse gas emissions keep rising and no effective measures are taken immediately. Our findings provide important implications for the adaption and mitigation of globally connected extreme heatwaves.
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Affiliation(s)
- Ming Luo
- Guangdong Provincial Key Laboratory of Urbanization and Geo-simulation, School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China
- Institute of Environment, Energy, and Sustainability, The Chinese University of Hong Kong, Hong Kong, SAR, China
| | - Sijia Wu
- Guangdong Provincial Key Laboratory of Urbanization and Geo-simulation, School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China
| | - Gabriel Ngar-Cheung Lau
- Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08540-6654, USA
| | - Tao Pei
- State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhen Liu
- Earth, Ocean, and Atmospheric Sciences (EOAS) Thrust, Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, China
| | - Xiaoyu Wang
- Guangdong Provincial Key Laboratory of Urbanization and Geo-simulation, School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China
| | - Guicai Ning
- School of Atmospheric Physics, Nanjing University of Information Science & Technology, Nanjing 210044, China
| | - Ting On Chan
- Guangdong Provincial Key Laboratory of Urbanization and Geo-simulation, School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuanjian Yang
- School of Atmospheric Physics, Nanjing University of Information Science & Technology, Nanjing 210044, China
| | - Wei Zhang
- Department of Plants, Soils, and Climate, Utah State University, Logan, UT 84322-4820, USA
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Brunner L, Voigt A. Pitfalls in diagnosing temperature extremes. Nat Commun 2024; 15:2087. [PMID: 38499558 PMCID: PMC10948863 DOI: 10.1038/s41467-024-46349-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 02/23/2024] [Indexed: 03/20/2024] Open
Abstract
Worsening temperature extremes are among the most severe impacts of human-induced climate change. These extremes are often defined as rare events that exceed a specific percentile threshold within the distribution of daily maximum temperature. The percentile-based approach is chosen to follow regional and seasonal temperature variations so that extremes can occur globally and in all seasons, and frequently uses a running seasonal window to increase the sample size for the threshold calculation. Here, we show that running seasonal windows as used in many studies in recent years introduce a time-, region-, and dataset-depended bias that can lead to a striking underestimation of the expected extreme frequency. We reveal that this bias arises from artificially mixing the mean seasonal cycle into the extreme threshold and propose a simple solution that essentially eliminates it. We then use the corrected extreme frequency as reference to show that the bias also leads to an overestimation of future heatwave changes by as much as 30% in some regions. Based on these results we stress that running seasonal windows should not be used without correction for estimating extremes and their impacts.
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Affiliation(s)
- Lukas Brunner
- Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria.
| | - Aiko Voigt
- Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria
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Kapwata T, Gebreslasie MT, Wright CY. An analysis of past and future heatwaves based on a heat-associated mortality threshold: towards a heat health warning system. Environ Health 2022; 21:112. [PMID: 36401226 PMCID: PMC9675182 DOI: 10.1186/s12940-022-00921-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Heatwaves can have severe impacts on human health extending from illness to mortality. These health effects are related to not only the physical phenomenon of heat itself but other characteristics such as frequency, intensity, and duration of heatwaves. Therefore, understanding heatwave characteristics is a crucial step in the development of heat-health warning systems (HHWS) that could prevent or reduce negative heat-related health outcomes. However, there are no South African studies that have quantified heatwaves with a threshold that incorporated a temperature metric based on a health outcome. To fill this gap, this study aimed to assess the spatial and temporal distribution and frequency of past (2014 - 2019) and future (period 2020 - 2039) heatwaves across South Africa. Heatwaves were defined using a threshold for diurnal temperature range (DTR) that was found to have measurable impacts on mortality. In the current climate, inland provinces experienced fewer heatwaves of longer duration and greater intensity compared to coastal provinces that experienced heatwaves of lower intensity. The highest frequency of heatwaves occurred during the austral summer accounting for a total of 150 events out of 270 from 2014 to 2019. The heatwave definition applied in this study also identified severe heatwaves across the country during late 2015 to early 2016 which was during the strongest El Niño event ever recorded to date. Record-breaking global temperatures were reported during this period; the North West province in South Africa was the worst affected experiencing heatwaves ranging from 12 to 77 days. Future climate analysis showed increasing trends in heatwave events with the greatest increases (80%-87%) expected to occur during summer months. The number of heatwaves occurring in cooler seasons is expected to increase with more events projected from the winter months of July and August, onwards. The findings of this study show that the identification of provinces and towns that experience intense, long-lasting heatwaves is crucial to inform development and implementation of targeted heat-health adaptation strategies. These findings could also guide authorities to prioritise vulnerable population groups such as the elderly and children living in high-risk areas likely to be affected by heatwaves.
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Affiliation(s)
- Thandi Kapwata
- Environment and Health Research Unit, South African Medical Research Council, Johannesburg, 2028, South Africa.
- Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, 0028, South Africa.
| | - Michael T Gebreslasie
- School of Agriculture, Earth, and Environmental Sciences, University of KwaZulu-Natal, Durban, 3629, South Africa
| | - Caradee Y Wright
- Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, 0028, South Africa
- Environment and Health Research Unit, South African Medical Research Council, Pretoria, 0084, South Africa
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Abstract
Compound MHW-OAX events, during which marine heatwaves (MHWs) co-occur with ocean acidity extreme (OAX) events, can have larger impacts on marine ecosystems than the individual extremes. Using monthly open-ocean observations over the period 1982–2019, we show that globally 1.8 in 100 months (or about one out of five present-day MHW months) are compound MHW-OAX event months under a present-day baseline, almost twice as many as expected for 90th percentile extreme event exceedances if MHWs and OAX events were statistically independent. Compound MHW-OAX events are most likely in the subtropics (2.7 in 100 months; 10°−40° latitude) and less likely in the equatorial Pacific and the mid-to-high latitudes (0.7 in 100 months; >40° latitude). The likelihood pattern results from opposing effects of temperature and dissolved inorganic carbon on [H+]. The likelihood is higher where the positive effect on [H+] from increased temperatures during MHWs outweighs the negative effect on [H+] from co-occurring decreases in dissolved inorganic carbon. Daily model output from a large-ensemble simulation of an Earth system model is analyzed to assess changes in the MHW-OAX likelihood under climate change. The projected long-term mean warming and acidification trends have the largest effect on the number of MHW-OAX days per year, increasing it from 12 to 265 days per year at 2 °C global warming relative to a fixed pre-industrial baseline. Even when long-term trends are removed, an increase in [H+] variability leads to a 60% increase in the number of MHW-OAX days under 2 °C global warming. These projected increases may cause severe impacts on marine ecosystems. Compound extreme events in two or more oceanic ecosystem stressors are increasingly considered as a major concern for marine life. Here the authors present a first global analysis on compound marine heatwave and ocean acidity extreme events, identifying hotspots, drivers, and projecting future changes.
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Vecellio DJ, Wolf ST, Cottle RM, Kenney WL. Utility of the Heat Index in defining the upper limits of thermal balance during light physical activity (PSU HEAT Project). INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2022; 66:1759-1769. [PMID: 35778555 PMCID: PMC9418276 DOI: 10.1007/s00484-022-02316-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 06/07/2022] [Accepted: 06/18/2022] [Indexed: 06/01/2023]
Abstract
Extreme heat events and consequent detrimental heat-health outcomes have been increasing in recent decades and are expected to continue with future climate warming. While many indices have been created to quantify the combined atmospheric contributions to heat, few have been validated to determine how index-defined heat conditions impact human health. However, this subset of indices is likely not valid for all situations and populations nor easily understood and interpreted by health officials and the public. In this study, we compare the ability of thresholds determined from the National Weather Service's (NWS) Heat Index (HI), the Wet Bulb Globe Temperature (WBGT), and the Universal Thermal Climate Index (UTCI) to predict the compensability of human heat stress (upper limits of heat balance) measured as part of the Pennsylvania State University's Heat Environmental Age Thresholds (PSU HEAT) project. While the WBGT performed the best of the three indices for both minimal activities of daily living (MinAct; 83 W·m-2) and light ambulation (LightAmb; 133 W·m-2) in a cohort of young, healthy subjects, HI was likewise accurate in predicting heat stress compensability in MinAct conditions. HI was significantly correlated with subjects' perception of temperature and humidity as well as their body core temperature, linking perception of the ambient environment with physiological responses in MinAct conditions. Given the familiarity the public has with HI, it may be better utilized in the expansion of safeguard policies and the issuance of heat warnings during extreme heat events, especially when access to engineered cooling strategies is unavailable.
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Affiliation(s)
- Daniel J Vecellio
- Center for Health Aging, College of Health and Human Development, Pennsylvania State University, 422 Biobehavioral Health Building, University Park, PA, 16802, USA.
| | - S Tony Wolf
- Department of Kinesiology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Rachel M Cottle
- Department of Kinesiology, Pennsylvania State University, University Park, PA, 16802, USA
| | - W Larry Kenney
- Center for Health Aging, College of Health and Human Development, Pennsylvania State University, 422 Biobehavioral Health Building, University Park, PA, 16802, USA
- Department of Kinesiology, Pennsylvania State University, University Park, PA, 16802, USA
- Graduate Program in Physiology, Pennsylvania State University, University Park, PA, 16802, USA
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