Heatwave takes a toll but no data on deaths
The disaster management division of the home ministry usually keeps a record of deaths and losses related to extreme weather events.
In April, east and southeast peninsular India saw an intense spell of humid heat (between April 5 and 7), and Odisha and West Bengal, one between April 15 and 30, which expanded over days to Bihar, Jharkhand and south peninsular India.
In May, Odisha, Gangetic West Bengal and parts of peninsular India saw an intense spell of heat (between May 1 and 7), Rajasthan, between May 16 and 26, with nine to 12 days that were classified either a heatwave or a severe heatwave (with temperatures nearing 50 degrees Celsius on some days), and Delhi and the National Capital Region, Haryana, southwest Uttar Pradesh and Punjab, also between May 16 and 26, with five to seven days that were classified a heatwave, with temperatures between 44 degrees C and 48 degrees C.
That’s already more than the average four to eight days of heatwaves around the country in the first three months of summer (March to May). And the rest of the month (May 26-31) promises to be no different.
Despite these unusually long heatwave spells, there is no record of heat deaths for this year. The disaster management division of the home ministry usually keeps a record of deaths and losses related to extreme weather events. It releases situation reports related to floods and extreme monsoon rainfall regularly. HT reached out to a home ministry spokesperson for a comment but did not get one immediately.
“During the heat spells, the relative humidity in coastal areas over east India was well over 50% and over northwest India, around 20%-30%. Humid heat can have very severe health impacts and we fear that a large number of people may have been impacted,” said a senior India Meteorological Department (IMD) official, who spoke on condition of anonymity. These heat spells coincided with the Lok Sabha elections being held between April 19 and June 1.
Last year, Kiren Rijiju, ministry of earth sciences, informed the Rajya Sabha that in recent years, deaths due to heatwaves have decreased significantly. “However, the figures for the year 2023 are not yet updated by the National Crime Record Bureau (NCRB), ministry of home affairs. It is a fact that annual temperature is increasing globally and the impact of the same is reflected in the increase in heatwaves in various parts of the globe, including India. IMD issues forecast and warnings related to severe weather events, including heatwaves, in different spatial and temporal scales and shares the same with public as well as disaster management authorities so as to initiate required mitigation measures,” he said on July 27 last year.
Government officials, who asked not to be named, pointed out that it is the responsibility of the states at the district magistrates’ level to take measures to reduce loss of life due to heatwaves and maintain data on deaths. “It is very difficult to define the death due to heatwaves, if a person has died due to exhaustion. Nonetheless, we keep writing to the states to take measures,” one of them said.
India already has national guidelines on heatwaves, explicitly laying out the roles and responsibilities of the central and state government agencies, district administrations, local self-governments, NGOs, civil society organizations and other stakeholders, said a second official.
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“The NDMA (National Disaster Management Authority) conducts workshops to sensitise states and Union territories about the need to prepare and implement their heatwave action plans, share best practices on management, sensitising the community through social media, print/electronic media advertisements on protection. It is the states/UTs which must do the work on the ground as they are better prepared to deal with heatwave conditions,” the official said.
The numbers are likely to be significant.
“In April last year, an intense humid heatwave hit India. While the total number of deaths related to that heatwave is unknown, it’s likely hundreds or even thousands of people would have died. In Europe, which is less hot and has a less exposed population, 70,000 deaths were linked to high temperatures in a single year,” said Friederike Otto, senior lecturer in Climate Science at Imperial College London, in an interview to HT in April.
According to scientists, at wet bulb temperatures above 35°C, even fit people will overheat and potentially die within six hours.
Wet bulb temperature is the lowest temperature to which air can be cooled by the evaporation of water into the air at a constant pressure. A wet-bulb temperature (TW) of 35°C marks our upper physiological limit – approximately 40 degree C temperature with 70% relative humidity.
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But it always does not need to be that precise combination to kill. A wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts, according to “the emergence of heat and humidity too severe for human tolerance,” according to a paper led by scientists from Jet Propulsion Laboratory/California Institute of Technology, USA, Department of Earth and Environmental Sciences, Columbia University.
In 2003, for example, around 72,000 people were killed in heatwaves in Europe; in 2010, around 56,000 people in Russia died due to a heatwave and 20,000 Somalis due to drought. Regions affected by the deadly 2003 European and 2010 Russian heatwaves experienced wet bulb temperature values no greater than 28°C, as per the study.
The paper, which analysed temperature records from 1979 to 2017, found wet bulb hotspots (with wet bulb temperatures exceeding 31 degrees C) have emerged in eastern coastal India, Pakistan and northwestern India, and the shores of the Red Sea, Gulf of California, and southern Gulf of Mexico.Worse may follow. According to the study, wet bulb temperatures could regularly exceed 35 degrees C in parts of South Asia and West Asia by the third quarter of the 21st century.
“There are two types of heatwave deaths – exertional, which is caused when one exerts in direct sunlight and their body heats up. They are not able to cool down by sweating and then they die. Only 10% of heatwave deaths are such exertional deaths. The non-exertional deaths happen among the vulnerable, the old, sick, infants who are not able to cool down even at night, their kidneys and heart start failing following dehydration. These people may not have access to cooling at home and they can die anywhere, even at home, since it’s not related to exertion. These are not categorised as heat strokes and are hence, possibly not counted as heat deaths at all,” said Dileep Mavalankar, head of the Indian Institute of Public Health (IIPH), Gandhinagar.
“In 2010, in Ahmedabad there were 800 excess deaths in a week during the heatwave period. Those excess deaths helped us identify the mortality burden of heat. We saw a similar pattern in Nagpur. So it’s critical that the government track all causes of excess mortality during extreme heat and make that data available,” added Mavalankar.
Climate change is increasing risks to human health by increasing exposure and vulnerability to extreme heat events like heatwaves, humid heat, heat domes. In 2013-22, compared with 1991-2000, the estimated average annual heat-related mortality increased by 85%, driven by both warming and changing demographics, globally, the National Disaster Management Authority said in its report on “Autopsy Findings In Heat Related Deaths”, released earlier this year.
But in another report, titled “Beating the Heat: How India Successfully Reduced Mortality Due To Heat Waves” , released in 2021, the agency claimed that deaths due to heatwaves have reduced remarkably from 2,040 in 2015 to four in 2020.
Between 1992 and 2015, there were 24,223 deaths across the country, the report said. But experts flag that heatwave mortality is not being effectively documented. Low heatwave mortality in 2020 may not mean mortality is in fact declining.
“The northern and central parts of India are currently experiencing severe heatwaves, with the IMD forecasting no relief until June. This situation highlights the immediate impacts of climate change and poses significant dangers to public health. According to the IPCC, heatwaves will be the biggest health risk in South Asia,” said Vishwas Chitale, sSenior programme lead, Council on Energy, Environment and Water (CEEW), in a statement.
“To build resilience, India’s heat action plans must shift from a response-centric to a preparedness-centric approach, mapping granular-level heat risks to help administrators prioritise health interventions. The CEEW team jointly with Thane Municipal Corporation developed a first-of-its kind heat action plan for Thane city that provides assessment of heat risks at ward level. Moreover, it is crucial for the public to follow alerts and guidelines of do’s and don’ts issued by government agencies,” added Chitale.
