Several heatwave indices failed to capture severity of extreme weather: Study
heatwaves have become more frequent and intense, emerging as a significant contributor to heat-related deaths. Researchers said that this underscores the urgency of recognising their impact and severity.
In the study, published in the journal Nexus, the researchers from The Hong Kong Polytechnic University analysed six available heat wave indices, including the Wet Bulb Globe Temperature (WBGT) index and Canada's humidex.
WBGT index was first developed in the 1950s by the US military to prevent heat-related illnesses in training camps.
The authors found that five of them failed to identify dangerous heat stress days during the heatwaves of Spain and the US in 2022 and those in 2023 in India's West Bengal and Uttar Pradesh.
Because of low humidity, the air was largely dry during these heat waves, even as these regions registered record-breaking temperatures, they said.
How lethal a heat wave is depends not only on temperatures recorded, but also humidity in the air, the researchers said.
They explained that just as how humid air can be a reason for severe fatality even under low temperatures, conversely, dry air can somewhat counter the impact of high temperatures, thereby contributing towards underestimating the actual heat stress on such days.
The authors found that of the six indices they studied, only one — the 'lethal heat stress index' — was able to account for these countering effects of dry air, and therefore, performed better in identifying days with dangerous heat wave conditions.
The lethal heat
