Extreme Heat Conditions

Source-This post on Extreme Heat Conditions has been created based on the article “Wet-bulb heat: A rising threat we cannot ignore” published in “Live Mint” on 31 May 2024.

UPSC Syllabus-GS Paper-3-Disaster management

Context– Recently, Delhi hit a record high temperature of 52.9°C, the highest ever recorded in India. Though unusual, the extreme heats this year have made temperatures near 50°C seem plausible. Many areas in India feel like ovens, and people say this summer is the hottest they’ve known.

What is the observation of Centre for Science and Environment (CSE) about the changing nature of the hot season?

The analysis shows that not only is the heat increasing, but the hot season has also become more humid over recent years. In Delhi, the average relative humidity during summer months has risen above 60%, significantly higher than the 52.5% recorded in the first decade of the millennium, creating a more sweltering environment.

What are the implications of high humidity?

1) High humidity weakens the cooling effect of perspiration, as sweat takes longer to evaporate.

2) Prolonged exposure to extreme humid heat can induce stress and even prove fatal.

3) While heatstroke deaths are few currently, global warming and rising humidity could soon make the fatality count shoot up.

A detailed article on heatwaves can be read here.

What is Wet-Bulb Heat?

Definition-Wet-bulb heat refers to readings of a thermometer with a bulb covered in water-soaked cloth, indicating the combined effect of temperature and humidity.

Tolerance Limit-Global human tolerance studies suggest that spending five hours or more outdoors in ‘wet-bulb heat’ above 35°C could be deadly.

Implication-

A) With rising moisture in the air, there may be worse conditions than the current dry heat readings.

B) Vulnerable Populations and Energy Needs-The myth of hardy Indian workers able to work under harsh conditions should not be believed. On current trends, the bulk of India’s population may be vulnerable to wet-bulb heat by mid-century.

Adopting clean technology options for electricity and proper planning are essential to address this impending crisis.

Question for practice

What is Wet-Bulb Heat? What are its implications?