2025-02-05 コロンビア大学
＜関連情報＞
- https://news.climate.columbia.edu/2025/02/05/huge-areas-may-face-possibly-fatal-heat-waves-if-warming-continues/
- https://www.nature.com/articles/s43017-024-00635-w
- https://www.science.org/doi/10.1126/sciadv.aaw1838
- https://iopscience.iop.org/article/10.1088/1748-9326/aaa00e
極端な暑さが死亡率に及ぼす影響 Mortality impacts of the most extreme heat events
Tom Matthews,Colin Raymond,Josh Foster,Jane W. Baldwin,Catherine Ivanovich,Qinqin Kong,Patrick Kinney & Radley M. Horton
Nature Reviews Earth & Environment Published:04 February 2025
DOI:https://doi.org/10.1038/s43017-024-00635-w
Abstract
Extreme heat threatens human life, evidenced by >260,000 heat-related fatalities collectively in the deadliest events since 2000. In this Review, we link physical climate science with heat mortality risk, including crossings of uncompensable thresholds (beyond which human core body temperature rises uncontrollably) and unsurvivable thresholds (lethal core temperature increase within 6 h). Uncompensable thresholds (wet-bulb temperatures ~19–32 °C) depend strongly on age and the combination of air temperature and relative humidity. These thresholds have been breached rarely for younger adults (~2.2% of land area over 1994–2023) but more widely for older adults (~21%). Unsurvivable thresholds (wet-bulb temperatures ~20–34 °C) were only exceeded for older adults (~1.8% of land area). Anthropogenic warming will lead to more frequent threshold crossings, including tripling of the uncompensable land area for young adults if warming reaches 2 °C above preindustrial levels. Interdisciplinary work must improve the understanding of the deadly potential of unprecedented heat and how it can be reduced. Ensuring reliable access for all to cool refugia is an urgent priority as the atmosphere threatens to increasingly overwhelm human physiology under climate warming.
人間の耐性を超える暑さと湿度の出現 The emergence of heat and humidity too severe for human tolerance
Colin Raymond, Tom Matthews, and Radley M. Horton
Science Advances Published:8 May 2020
DOI:https://doi.org/10.1126/sciadv.aaw1838
Abstract
Humans’ ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979. Recent exceedances of 35°C in global maximum sea surface temperature provide further support for the validity of these dangerously high TW values. We find the most extreme humid heat is highly localized in both space and time and is correspondingly substantially underestimated in reanalysis products. Our findings thus underscore the serious challenge posed by humid heat that is more intense than previously reported and increasingly severe.
気温と湿度に基づく、21世紀中の世界的な熱ストレス暴露の急増予測 Temperature and humidity based projections of a rapid rise in global heat stress exposure during the 21st century
Ethan D Coffel, Radley M Horton and Alex de Sherbinin
Environmental Research Letters Published: 22 December 2017
DOI:10.1088/1748-9326/aaa00e
Abstract
As a result of global increases in both temperature and specific humidity, heat stress is projected to intensify throughout the 21st century. Some of the regions most susceptible to dangerous heat and humidity combinations are also among the most densely populated. Consequently, there is the potential for widespread exposure to wet bulb temperatures that approach and in some cases exceed postulated theoretical limits of human tolerance by mid- to late-century. We project that by 2080 the relative frequency of present-day extreme wet bulb temperature events could rise by a factor of 100–250 (approximately double the frequency change projected for temperature alone) in the tropics and parts of the mid-latitudes, areas which are projected to contain approximately half the world’s population. In addition, population exposure to wet bulb temperatures that exceed recent deadly heat waves may increase by a factor of five to ten, with 150–750 million person-days of exposure to wet bulb temperatures above those seen in today’s most severe heat waves by 2070–2080. Under RCP 8.5, exposure to wet bulb temperatures above 35 °C—the theoretical limit for human tolerance—could exceed a million person-days per year by 2080. Limiting emissions to follow RCP 4.5 entirely eliminates exposure to that extreme threshold. Some of the most affected regions, especially Northeast India and coastal West Africa, currently have scarce cooling infrastructure, relatively low adaptive capacity, and rapidly growing populations. In the coming decades heat stress may prove to be one of the most widely experienced and directly dangerous aspects of climate change, posing a severe threat to human health, energy infrastructure, and outdoor activities ranging from agricultural production to military training.
