India is experiencing searing heat earlier than usual for the third consecutive summer, with extensive regions suffering from humid conditions. Scientists warn that climate change is increasing the frequency, duration, and severity of heatwaves, potentially endangering more than a billion lives. As national elections progress, the impact of this heatwave is more acute compared to 2023, the hottest year on record. The India Meteorological Department (IMD) has predicted an unusually high number of heatwave days from April to June.
Defining Heatwaves and New Indices
There is no global standard for defining heatwaves, but the IMD considers temperatures above 40°C in low-lying areas or 30°C in mountainous regions as heatwave conditions. The IMD has introduced a Heat Index that factors in humidity to provide a more accurate representation of how hot it feels. Tirthankar Banerjee from the Institute of Environment and Sustainable Development, Banaras Hindu University, suggests that lower thresholds for heat warnings might be necessary to better protect public health.
Mapping Health Risks and Early Warning Systems
Banerjee and colleagues have mapped the health risks associated with heatwaves by examining excess mortality in ten cities across different climate zones from 2008 to 2019. Their study considers factors like wind speed, solar radiation, temperature, and humidity to improve early warning systems. Rajib Chattopadhyay, a meteorologist at the Indian Institute of Tropical Meteorology, emphasizes the need to tweak regional heat action plans (HAPs) to account for dry and moist heat stress.
Impact of Moist and Dry Heatwaves
Chattopadhyay’s research indicates a 30% increase in moist heat strength from 1980 to 2020, with areas under heat stress expanding by 30% to 40% over the past 70 years. The study found that dry heat has worsened across most parts of India, with climate change-induced moisture making conditions even hotter, particularly in southeastern coastal areas.
Improving Heat Advisories and Heat Action Plans
Improving heat advisories is crucial, especially for families experiencing higher indoor temperatures compared to outdoors. Sophisticated heat indices or thermal comfort forecasts should guide HAPs rather than simple temperature thresholds. Since the launch of India’s first HAP in Ahmedabad in 2013, which saved over 1000 lives, nearly 40 similar strategies have been implemented nationwide. Ahmedabad’s HAP now includes nighttime temperatures due to rising nocturnal heat.
Interconnection of Heatwaves and Other Climate Hazards
Heatwaves often coincide with other extreme weather events, such as heavy rainfall, highlighting the importance of robust building designs. Hydrologist Poulomi Ganguli from IIT Kharagpur points out that humid heat can trigger strong rain bursts, affecting roof designs. Climate change-related shifts in atmospheric currents have made heatwaves more persistent and longer since the late 1990s, as noted by climate attribution expert Arpita Mondal from IIT Bombay.
Mechanisms and Consequences of Heatwaves
Heatwaves in India are triggered by a series of atmospheric and oceanic events, such as persistent high-pressure systems and disrupted weather patterns. El Niño and high-pressure systems blocking sea breezes have caused record high temperatures in many parts of India this year. Deadly heatwaves, driven by climate change, threaten India’s development, potentially reversing progress in poverty alleviation, health, and economic growth.
Since 1992, over 24,000 deaths in India have been attributed to heatwaves. With heatwaves becoming more frequent and intense, millions of lives and livelihoods are at risk. By 2050, extreme heat could decrease outdoor working capacity by 15% during daylight hours, impacting India’s GDP and living standards. The study suggests that heatwaves could severely affect over 90% of the population, placing them in an extreme heat “danger” zone.
Addressing Heat Vulnerability
To mitigate the impacts, the study recommends updating extreme weather assessments to include the Heat Index and its effects on sustainable development. Urban greening and heat-health packages for low-income communities are critical for building heat resilience. As India continues to scale up its heat action plans, it is imperative to reassess the metrics for climate vulnerability to better protect its population from the escalating threat of heatwaves.
Read Now:Unsold Bananas Highlight Crumbling Infrastructure and Soaring Losses in India
