The emergence of heat and humidity too severe for human tolerance

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.

Multi-hazard climate risk projections for the United States

“…3). A recent study by Raymond et al (2020) noted that the Gulf Coast region has frequently surpassed the heat-humidity habitable limits and our findings further reinforce that in future heat waves will be more common in the region. The concentration of population and infrastructure in urban counties and coastal areas increase exposure (Fig.…”

Outdoor Thermal Comfort and Building Energy Use Potential in Different Land-Use Areas in Tropical Cities: Case of Kuala Lumpur

“…This combined impact of temperature and humidity is better indicative of the physiological experience of heat, and the higher the humidity, the higher the perceived temperature, the higher the potential health risks, the poorer the thermal comfort, and hence, the higher the building energy use to keep the indoor conditions at favorable levels. Despite recent sporadic studies that demonstrated that humid heat is increasingly a global trend [11] and highlighted urban moisture as a prevalent issue and an aggravator of heat island impact [12][13][14][15] with important implications on health and energy use [16], the scholarly discourse on urban microclimate under current and future climatic trends is still heavily dominated by air temperatures alone. In this respect, our presuppositions with regards to the thermal comfort in different land-use areas need also to be revisited, especially in tropical and subtropical cities (compared to mid-latitude cities), because (1) high air temperatures and UHI in tropical and subtropical cities is an almost year-round critical phenomenon, (2) humidity levels are rather high due to frequent and intense precipitation, and (3) ventilation is low due to overall lower wind speed values, further exacerbating the adverse impact of humidity on perceived temperatures.…”

Beyond continuationism: climate change, economic growth, and the future of world (dis)order

“…While there is much uncertainty, current projections are that agriculture across the planet would be severely threatened in a three and especially four degree world (possibly involving 20-40 percent yield reductions in key staples), which multiple scientists believe could only support a global population of four billion or less (Vince 2019;Cribb 2019, 79). Furthermore, scientists project that, due to a combination of sea level rise and population growth, up to 300 million people will be at risk of displacement from regular coastal flooding by 2050 (Kulp and Strauss 2019), while populations across North Africa, the Middle East and South Asia would be regularly subjected to lethal 'wet-bulb temperatures' (the 35 C threshold beyond which sweat-based cooling mechanisms lose their effectiveness even for healthy individuals) (Raymond et al 2020). Therefore, preventing international conflict and mass mortality in this context would likely require 'cooperating as never before to radically reorganize our world' through massive programs of resettlement and relocation to shift population centres and agricultural production to more habitable regions (Vince 2019).…”