Living in India, heat is an ever-present factor for all of us. Indeed it seems unending, especially if you happen to live in the centre of the subcontinent, Nagpur, for instance. We've learnt to accept it, with difficulty, but something has changed since at least 2015. The texture is different now. No longer is it just scalding. If you think this is more of the normal, no, and you may not be capable of weathering it. This is not your grandfather’s heat. You can't find your second wind and it's just the morning.

Heat comes in two incarnations—dry heat and damp heat. The first is the familiar feeling of being inside an oven; your nose dries out and skin gets drier and drier. But you sweat and cool off. In wet heat, though, you feel sticky, you breathe as if through a wet cloth. You leak from every pore, as long as the sweat glands work.

In the dry heat, survival is not an issue, though you feel uncomfortable, if you sweat and drink plenty of water. But temperatures above 38-40Celsius make that difficult. Still, it's bearable, but there's a twist, the early onset of high temperatures since 2015. That indicates it could get a lot worse.

On February 16, temperatures in Bhuj, Gujarat, shot up to 40.3C, a new monthly record. The same day, Kandla, 70 km from Bhuj, showed 38.1C, a monthly record for the place. This is deep winter in Delhi and a time when everywhere else in India it's cool or cold.

These “temperatures [are] unprecedented for this time of year,” says Maximiliano Herera, climatologist and expert on weather extremes. “According to climatologist Rajesh Kapadia, the 40C recorded in Bhuj is the earliest ever in India, and also the earliest ever in Asia, together with the February 16, 2018, recorded at Makkah, Saudi Arabia.”

We can't do anything, the heat is killing us. I feel like my life force is being stripped by heat.

This year, in February, India had an average temperature of 23.1C, 1.36C above the 1981-2010 baseline. It was the second hottest February on record after 2016. Cool in the south, extremely warm in the Northwest, up to 4C above average, he writes.

Herrera calls it an “endless heat wave.” On February 21, Narnaul In Haryana with 35C broke its own February record. Varanasi with 35.5C had its hottest February day since 1884 (36.1C). On March 4, “Karwar with 40.2C and Honavar with 39.4C (both in Karnataka) had their hottest day ever (for any month).” The air would have felt like viscous liquid in the two coastal towns.Finally, July 4 was the hottest day in the world since records began to be kept. That was exceeded on July 5,

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Adapa Satyanarayana is around 60. He belongs to Kapavaram village in the West Godavari district of Andhra Pradesh. He's both a tenant farmer and farm worker. Heat has been a constant in his life, but now it's an ordeal. He has diabetes, which makes heat-related illness, such as heat stroke, more likely. “It’s not like the old days. It’s continuously hot and exhausting, and draining our energies. It's hard to recover,” he says.

“Working in the direct sun is unavoidable for me. I don’t have any wealth to fall back on.”

If it gets too much, he hobbles into some shade nearby. Sometimes, the person he is working for objects to this retreat. “We can't do anything, the heat is killing us.” As he gets older, it's got worse, causing headaches, dizzy spells and heat-induced confusion. Longer and longer heat extremes are making farm work difficult. “I feel like my life force is being stripped by heat.”

In a warming climate, weather systems have more energy to work with. The energy goes into producing intense storm systems, and enormous high pressure systems.

Rising heat is a complex story, that comprises more and hotter spells that last longer, how early in the year it starts to get hot and how long it takes to subside, the shorter intervals between heat extremes, points perhaps to India crossing a threshold. A small rise in global mean temperatures shifts the entire country into extreme heat events.

While the world has been warming for a couple of centuries, India has warmed slightly slower than, for example, the Middle East. But, “since it's already a hot country, even moderate warming is worsening the suffering of people,” Herrera says.

Extreme heat is the most direct physical result of fossil fuel combustion. The baseline switches to warmer temperatures that we’re experiencing because of climate change drive up the likelihood of heat waves in other seasons too, not just summer.

There are other wrinkles in this story, short-term yearly oscillations being one. The wild card here is La Nina—a weather pattern in the Pacific Ocean where strong winds blow warm surface waters from South America to Indonesia. It's been brewing for the last two years, sometimes waxing, sometimes waning, confounding observers all the time. The consensus, however, is settling around the feeling that it will get hotter sooner and for longer periods.

In India and Pakistan, we just burn. Back to back heat tsunamis in March and April last year engulfed the region. This is normally the beginning of summer, when you notice that it's getting warm. But you also get cooler days that bring some relief. So this surfeit of heat is the clearest sign that even a tiny uptick in average temperatures can lead to extreme heat. In the words of Maximiliano Herrera, this is an “infinite heat wave”.

The March-April 2022 India-Pakistan heat wave is vying for a spot among the most extreme events ever recorded globally.  In March, Wardha in Maharashtra recorded 45C, while Nawabshah in Pakistan sweltered in 49.5 degrees, a number reached only at the height of summer, in June-July. It just kept hotter and hotter with no sign of relief, on the roads, in backyards, in the air and at home.

Tap water was hot enough to make tea. India and, for that matter, Pakistan and Bangladesh, are on the frontline of climate disasters year round, but we are particularly affected from March through June. Even the thought of cooler days seemed unreal in that atmosphere. The way the heat steepled in India in these months is matched only by the way the delta variant of the Coronavirus pandemic tore through the country in these very months last year. The difference was in the number of dead, vastly greater in the pandemic, but mass heat deaths are a distinct possibility in the future. That should send a chill down our spines.

In a warming world caused by human activity, such longer, harsher, wider heat conditions will be routine rather than an exception.  Extreme heat is the most direct physical result of fossil fuel combustion. This wave or event is an effect of global warming that has already happened. The baseline switches to warmer temperatures that we’re experiencing because of climate change drive up the likelihood of heat waves in other seasons too, not just summer. What makes it hard to comprehend is that we’re simultaneously experiencing and processing it.

Fuelled by climate change, encouraged probably by La Nina—a climatic phenomenon in the southern Pacific Ocean where strong winds blow warm surface waters from South America to Indonesia,  and seasoned by local conditions--the heat swamped India and Pakistan earlier than usual that year, lasting longer, breaking previous records, and causing hundreds of deaths. In this weather, the air tastes burnt, smells acrid. A kind of burning rubber smell accompanies your breathing. It could be singed hair follicles in the nose.

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Heat is a silent killer, it sneaks up on you. It's just discomfort at first but if you don't take notice you could end up dead. What makes heat exposure and death different from drowning and getting caught in a burning building is that you'll notice the last two and try to help, but heat death happens in silence.

Global warming means our climate, like Chennai, has three phases, hot, hotter, hottest. We have more blazing hot days, the summer lasts longer and it begins earlier. This is potentially catastrophic for us, given the narrow range in which the body maintains itself. In extreme heat, complications develop as internal body temperatures rise in response to external conditions.

“Heat illness depends on how long you’re exposed, the time of day, whether you’re doing strenuous work, whether you’re drinking water or not,” says Khyati Kakkad, paediatrician at LG hospital in Ahmedabad. She was lead author of a 2014 paper that compared infants’ heat-related illness in a 2010 heat wave to the years before and after, and brought out the importance of simple adaptive measures. When she found newborns with high temperatures were all coming from a top floor neonatal ward, she helped shift it to the ground floor, which made all the difference.

In India, the annual mean, maximum and minimum temperatures averaged for 1986–2015 show a significant warming trend,  0.15C, 0.15C and 0.13C per decade, respectively, according to the Assessment of Climate Change over the Indian Region, a 2020 report of the Union Ministry of Earth Sciences (MoES).

These changes will be more pronounced for cold nights and warm nights. Pre-monsoon heat wave frequency, duration, intensity and area coverage are projected to substantially increase in the 21st century, the report says.

As for Herrera, “The world will keep warming, so we should expect these heat waves to become more frequent and intense and the cold spells rarer but still present from time to time.”

This year the heat arrived earlier than the last year, prompting the India Meteorological Department to issue an alert in February itself.

“It's the combination of heat exposure and existing vulnerabilities that make for deadly outcomes in our settings,” says Gulrez Shah Azhar, lead author of a landmark study that launched further heat studies. The study, published in 2014, assessed excess deaths in Ahmedabad in May, 2010 when temperatures reached 46.8C. It counted an estimated  1,344 excess deaths---a 43 per cent increase---relative to a combined May 2009 and May 2011 reference period. Later, heat action for different places was developed.

In a future of high heat when land, air and water all seem to be on fire, it will be impossible to do outdoor work, which is hard enough even now.

Between 1992 and 2015, heat waves officially caused 24,223 deaths across the country, according to the National Disaster Management Agency’s heat wave book. The year 2015 had 2,040 heat deaths; 2016, 1,111; 2017, 384; 2018, 25;2019, 226; 2020,4. In India, heat deaths are under-reported.

High temperatures can be mitigated by staying indoors in air conditioning, showering and drinking fluids. “When a big proportion of population doesn't have cool indoors, or air conditioning, or electricity, or indoor water storage or supply, then the same heat will be deadly.” In our country, your home can be an oven in the summer.

Azhar, meanwhile, went to the U.S., and after stints at Rand Corporation and the University of Washington, he is now an independent researcher. He remembers the research team coming down with fever while doing a study on heat.

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In a future of high heat when land, air and water all seem to be on fire, it will be impossible to do outdoor work, which is hard enough even now. Working in the tropical sun is a serious health hazard. The costs pile up. A 2022 paper—"Global labour loss due to humid heat exposure underestimated for outdoor workers"—in the journal Environmental Research Letters, says “labour losses are most pronounced in India, which accounts for almost half the global losses and experienced over four times the labour losses of the second most impacted country, China.”

It’s not just the deaths but the burden of disease induced by heat that is a problem, says Vidhya Venugopal, professor at the department of environmental health engineering at Sri Ramachandra University, Chennai.

In their studies on heat stress among organised and unorganised workers, Vidhya Venugopal says, 22 per cent of  stone quarry workers had reduced kidney function. Excess heat, dehydration and heavy exertion contributed and if unattended, could lead to Chronic Kidney Disease (CKD). The studies found that reduced kidney function is much higher in the unorganised sector at 27.6 per cent than the organised sector (16.8). The poor and unprotected are disproportionately affected by climate change.

“Most workers in unorganised sectors are unprotected by health insurance or lack facilities and do not come under the ambit of labour laws,” she says. In construction, the studies show, heat-related illness is 87 per cent; productivity loss is 27 per cent, risk of accidents 26 per cent.

About 75 per cent of  India's workforce are exposed to heat, according to the World Bank. “As over half of India's GDP is derived from heat-exposed industries such as agriculture, mining, and construction, even a slight GDP decline could influence recovery from financial setbacks,” she says.

The Met Department issues alerts only for air temperatures and not for humid heat. Venugopal suggests, “heat alerts must take into account all of the contributing aspects, including humidity, that describe the worker's health in terms of the safest possible temperature for a worker.”

"The way IMD defines a heat wave needs to be changed,” says Chandra Bhushan, public policy expert and the president and CEO of the International Forum for Environment, Sustainability and Technology. Peninsular India suffers from high humidity with relatively low temperatures. “The present definition doesn’t take into account those conditions.”

The higher the wet-bulb temperature, the harder for the body to sweat and cool down. The air is saturated and cannot take any more water.

For instance, take wet bulb temperature (WBT). With 30C as the temperature and 90 per cent relative humidity, we get an extremely uncomfortable 28.62 degrees C.

Instead of waiting for the Centre to revise the definition of a heat wave, the southern states can ask the Centre directly, Bhushan says.  As for workers, factory law speaks about all this but in such a generic way as to appear meaningless.

“What we need now is specific numbers or range,” he says.

In conditions of high humidity the sweating mechanism which helps reduce core temperatures collapses. Humidity makes it hard for the body to cool down. The higher the wet-bulb temperature, the harder it is for the body to sweat and cool down. That’s because the air is saturated and cannot take any more water. Research says if WBT crosses 35C, sweating doesn’t work and you overheat. No human, however healthy and strong, will make it in these conditions beyond six hours.

Global warming is creating precisely such conditions of rising heat and humidity, according to the study in Environmental Research Letters.

The tropics house approximately three billion people and will be worst hit if global warming crosses 1.5C. At that limit, WBT will creep to 35C but not cross it, says a 2021 paper in Nature Geoscience. But even lower WBT, say around 27-28C, can turn people into zombies.

Put simply, you cannot survive in high humid heat, which climate change has already wrought.

Large swathes of India, Pakistan and Bangladesh will have WBT of 35C by the end of the century, according to a 2017 paper in Science Advances. But that abstract danger turns into an immediate, here-and-now catastrophe in another, 2020 paper, in the same publication.

Here, researchers analysed hourly observational readings from 7,877 weather  stations around the world from 1979 to 2017. It found that WBT has, indeed, crossed 35C, the limit of survivability, and such instances doubled in their study period. They found thousands of zombifying short, localised episodes, lasting a few hours, in Asia, Africa, Australia, North America and South America. India, Pakistan and Bangladesh experienced repeated instances of this lethal combo.

Hot, humid death appeared 14 times in Damman, Saudi Arabia, Doha, Qatar and Ras Al Khaimah, UAE.  The world over, WBTs above 30C doubled; believed-to-be-hardly-ever 31C occurred 1,000 times; thought-to-be-never 33C materialised 80 times. These bursts are increasing in frequency and intensity. Their sweep will increase as the planet warms.

Closer home, Bob Kopp of Rutgers University showed in 2015 that in Kakinada, Andhra Pradesh, WBT touched 30C.There were days when it didn’t fall below 27.777C. The sea off Kakinada drove humidity up. Whenever and wherever the sea breeze blows onto an already-searing shore, WBT soars. In these circumstances, the sea breeze doesn’t refresh, it turns the place into a potential death zone.

Local and regional practices are also responsible. A 2020 study from Indian, German and US researchers in Nature Geoscience, says intensive irrigation in the Indo-Gangetic plain has worsened humid heat.

In 2010, Steven Sherwood and Mathew Huber  proposed the concept of physiological limit of human survival based on WBT. “Peak heat stress, quantified by wet-bulb temperature T_W, is surprisingly similar across diverse climates today. T_W never exceeds 31C. Any event of 35C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global mean warming about 7C, calling the habitability of some regions into question,” they wrote.

They felt even a healthy, at-rest, in-shade person would overheat if WBT compromised the sweating mechanism. Since such copybook conditions don’t exist most of the time, lower WBTs can fell people.

If you cannot afford air conditioning, extreme heat waves of 50+ C or extreme dew points of 35C will become mass casualty events.

Many climate scientists thought WBTs would reach those limits at the end of the century. Highs of 35C felt like a long tether, not reached until very long into the future. That is the maximum a person can go, lingering at that level for some hours before overheating and dying, a condition we believe never happens. But researchers at Penn State say in their 2022 paper in the Journal of Applied Physiology we don’t have that long a rope.

“The researchers found that critical wet-bulb temperatures ranged from 25C to 28C in hot-dry environments and from 30C to 31C in warm-humid environments,” according to the article.

“The researchers added,” the article states, “ that because humans adapt to heat differently depending on the humidity level, there is likely not a single cut-off limit that can be set as the “maximum” that humans can endure across all environments.”

So a WBT much below 35C can kill, as can temperatures much above 40C. Indians, it appear, have no cover.

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Heat is a 74-year-old man, fitfully adrift, not zonked out yet, nor completely put-together, but not quite there. It is a homeless man, back on the pavement and legs splayed, coming alive suddenly, not knowing what happened to him earlier. Heat is birds panting to cool down, or a street dog panting and wheezing; panting helps them cool themselves.

The IMD prediction of an extremely hot April and May was on point. The onset of El Nino, the warming of the Pacific Ocean, contributes to the heat. But whatever cooks up a heat wave, it is a special, heightened concern for Christopher Burt, weather historian at IBM’s Weather Company and former blogger for Weather Underground.

“The local population in places such as the Persian Gulf region will have nowhere to hide. If you cannot afford air conditioning, extreme heat waves of 50+ C or extreme dew points of 35C will become mass casualty events,” says the Californian whose brush with warming-fuelled wildfires is an ongoing experience. Every fall since 2017 has featured months of choking smoke over much of the state and beyond.

“Prior to 2017, this was a rare occurrence, now it is the new normal,” Burt says.

Last year was the pre-apocalypse. In January 2022 Argentina, Brazil, Paraguay and Uruguay in South America felt the heat; in June Japan reeled from its worst heat wave in 150 years. China too had several heat waves. From June to August, heat savaged different parts of Europe. Heat waves in February and May affected different parts of the US.

Back home, a significant warming trend has persisted over the last 20 years, says Jew Das, research associate at the National Institute of Technology at Warangal, Telangana. He published a paper in 2021 in the International Journal of Climatology on heat wave magnitude under different emission scenarios.

“It indicates that the magnitude is expected to intensify, with longer duration, over India,” Das says. Heat waves claim thousands of lives in India. A 2021 study published in Elsevier, says mortality rates per million for heat waves have risen 62.2 per cent in the last four decades. Mean temperatures have risen by more than 0.5C from 1960 to 2009. The likelihood of a mass death event of more than 100 people rose by 146 per cent with an increase of just 0.5C in summer mean temperatures, according to a 2017 study in Science Advances.

 The authors analysed IMD data and found that “accumulated intensity, count, duration, and days of Indian heat waves have also increased over most of the country and especially in the northern, southern, and western parts of India.”

Southern and western India were hit by 50 per cent more heat waves from 1985 to 2009 than in the 1960 to 1984 period. In years when heat wave days and summer mean temperature are above average, heat-related deaths also rise. But there's a silver lining, says Roxy Mathew Koll, a climate scientist at the Centre for Climate Change Research at the Indian Institute of Tropical Meteorology, Pune.

IMD forecasts for heat waves have improved; the public is on the lookout for quick measures, he says. There are scattered attempts in some regions to adjust school and work hours, for example, in Odisha and interior Maharashtra. 

“We need to have this as a policy at state government level, depending on the heat waves of each region. We have sufficient data to show which regions need policies based on heat waves,” Koll says.

India needs a long-term vision where we have policies to manage work hours, public infrastructure, schools, hospitals, workplaces, houses, transportation, and agriculture for heat waves to come

Apart from curbing greenhouse gas emissions and adopting commonsense approaches to beat the heat, direct compensation for the loss of livelihood  is needed to keep people from dying. It will help the poor tide over the climate disasters they have no part in producing.

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Heat is a silent killer, it sneaks up on you. Unnoticeable at times and unnoticed many times, heat exposure sets off a cascade of physiological processes that will kill if unaddressed. What makes heat exposure and death different from drowning and getting caught in a fire is that in the latter cases somebody might see you and come to your rescue. Heat death happens in silence.

Global warming means days with scorching temperatures have increased; the heat season is longer; hot temperatures are showing up early. This is potentially catastrophic for the narrow range within which the body maintains itself. 

In our country, the most important thing is drinking water. If water content in the body is fine, it helps by all means.

The human body maintains an optimal temperature of 37C. During the day, it ranges from 36C to 37.5C. Anything above that range is hyperthermia.  It’s not fever, which is an inflammatory response. A temperature above 40C is severe hyperthermia.

In his article "Severe non-exertional hyperthermia (classic heat stroke) in adults", published in UpToDate literature review through April 2022, Crawford Mechem, professor of emergency medicine at the Perelman School of Medicine, University of Pennsylvania, discusses the pathophysiology of heat illness.

The body gains heat from both metabolic processes and the environment. It has the ability to keep its temperature within the comfort range by absorbing and shedding heat as necessary. Heating and cooling is controlled by the hypothalamus, an area in the centre of the brain that controls the metabolism, temperature, weight and emotions. When the inside of the body starts heating up, the hypothalamus restores the temperature to the normal range. It stimulates the autonomic nervous system—a complex cluster of nerves that involuntarily modulates all kinds of internal body processes such as blood pressure, heart rate, enlarging blood vessels—to produce sweating and widen blood vessels.

Evaporation of sweat is the principal way the body dissipates heat. This works if it has enough fluids. People who are short on fluids cannot sweat and so overheat. Evaporation of sweat also doesn’t work if relative humidity is above 75 per cent. The other means by which the body cools down are: radiation (emission of infrared electromagnetic energy), conduction (direct transfer of heat to a cooler object) and convection (direct transfer of heat from a solid object to air).

Overheating produces a series of cascading processes. Your body needs more oxygen and you breathe in more air than normal, a condition called hyperapnea; the heart beats faster than 100 times a minute, a condition called tachycardia. The process by which food (sugars) is transformed into energy within the cells, called cellular respiration, dies down. Enzymes that regulate the rate of chemical reactions in the body stall. An inflammatory response follows.

The movement of blood changes. Splanchnic circulation—blood flow to the abdominal gastrointestinal organs including the stomach, liver, spleen, pancreas, small intestine, and large intestine—comes to a halt. That blood, charged with heat, is shunted to the skin and muscle, in the hope of the air absorbing it.

The diversion of blood reduces blood and thus oxygen to the gastrointestinal tract and the mucosa, its inner lining, gets perforated.

“Hepatocytes (cells helping the liver function), vascular endothelium (the inner cellular lining of blood vessels), and neural tissue are most sensitive to increased core temperatures, but all organs may ultimately be involved. In severe cases, patients develop multi-organ-system failure and disseminated intravascular coagulation (in some cases this leads to clotting and in some cases, to bleeding) ,” notes the article.

Your brain, built entirely of nerve cells, is most sensitive to heat. In high heat, these cells get denatured, linkages holding them together come undone.  In simple terms, they get cooked. 

The body’s response to heat ranges from mild to severe. “Heat-related illness is a spectrum of illnesses,” says Kakkad.On the one end, you have hypothermia plus rash.

“You take rest. You cool yourself. It also depends on the personality, whether you’re healthy or have comorbidities, whether you’re acclimated or not, whether you’re doing strenuous work or not, whether you’re drinking water or not.”

Then there are heat cramps, severe pain in the lower limbs because of dehydration.If unaddressed, it can lead to heat exhaustion, a higher version. If there is continuous high heat, the body cannot lose heat. Dehydration, electrolyte imbalance set in. You feel giddy, might want to throw up, and in some cases, you may have convulsions.

The severest body reaction is heat stroke. In this condition, muscular protein breaks down. The kidney cannot excrete the debris and is overwhelmed and shuts down. Intravascular fluid volume is low because sweat has already taken away fluids. (Blood is 90 per cent water.)

“You may have a circulatory collapse. There is no vehicle to send nutrients and oxygen to every part of the body,” says Kakkad. “All vital organs will get affected. The whole system unravels.”

These reactions to heat, she notes, are not water-tight compartments. They bleed into one another, if unattended and could get you into something serious.

“In our country, the most important thing to counteract these reactions is by drinking water. If water content in the body is fine, it helps by all means.”

When you sweat a lot and don’t drink enough water, your intravascular fluid volume will drop.  Blood thickens and may clot in some vessels. Kidneys will not work properly. It will lose or retain sodium. As Indians, we may have may have some idiosyncrasies in our response to heat. In places like Ahmedabad, heat victims come with more sodium in the blood. It’s called hypernatremia and in this condition you may have cramps, less urination, you’re thirsty, get cranky and have seizures. In certain cases, there is less sodium in the blood, hyponatremia, characterized by confusion, lethargy, and in some cases, cerebral oedema.

Kakkad  has treated heat-affected infants with rashes, nausea, dehydration, high sodium levels and kidneys temporarily shut down, with, sometimes, diarrhea.

“They don’t ask for water; their thermal regulation is not yet developed; they have larger surface area to take the heat in. It’s difficult for mothers to understand that their child is having a heat-related problem,” says Kakkad. “I am more worried about low sodium than borderline high sodium levels.”

Ice packs cannot be used for children because they’re prone to hypothermia. Kakkad and her team ask the infants’ mothers to buy a mosquito net and wrap a wet soft cotton cloth around it, keeping the upper part open. When the air passes through it, water in the cloth evaporates, providing a cooler micro environment. She also encourages mothers to wrap a wet bed sheet around cradles, and wet jute bags on corrugated roofs (if they’re living there) and windows and continue wetting them so that infants have a cooler environment.

For every degree Celsius the air warms, it guzzles 7 per cent water, creating a deadly combination of heat and humidity.

Apart from infants, the elderly are also at greater risk from heat exhaustion and heat stroke. Even young people are at risk in this high, long heat. People with comorbidities and people using certain medications can fall victim more easily. For example, drugs for high blood pressure induce more urination, draining fluid from the body. In high heat or humid heat, the loss of fluid is greater, making one susceptible to heat stroke. Not only that, those drugs alter blood flow to the skin, making it difficult to shed heat.

The thing with heat is anyone can die of it, in any of 27 ways, according to Camilo Mora, professor at the University of Hawaii, Manoa. In the paper, the authors explain how each mechanism is triggered. In this epic heat, no one is safe.

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Extreme heat is an effect of global warming that has already happened. This also raises the chances of heat waves in colder seasons. How does it happen? It starts with  a high pressure system. Hot air rises and expands and in normal circumstances helps reduce heat from the earth’s surface. When a high pressure system is parked over an area due to meteorological conditions, it acts as a lid obstructing the rising hot air. So the air sinks. As it is compressed, it warms and tries again to rise, where it again hits the lid, and sinks back down, and on and on, circulating up and back, getting hotter and hotter. The system also drives away beneficial cooler air currents in different patterns and dismantles clouds.

Then, everything—people, plants and trees, soils, ground, roads—bakes in the sun. Heat cannot escape into the atmosphere and the temperature rises. That produces a heat wave. Lack of rain boosts the cycle.  The energy that would have been used for evaporating moisture from plants and soils goes to heating up the already hot air. It also further erodes soils.

In coastal areas, and to some extent inland, too, where humidity is high, extreme heat builds up. For every degree Celsius the air warms, it guzzles 7 per cent water, creating a deadly combination of heat and humidity. India’s east coast, including the coastal regions and adjoining regions, swelters in this damp heat. 

More heat comes through urban heat islands where roads, buildings and infrastructure absorb heat, making places hotter still. Night temperatures that help people recover are rising, too.

All of this is happening in the context of a warmer background, which makes heat waves that much warmer and worse. Scientists say the average global temperature has risen by 1.1 Celsius since 1880. The larger part of warming has occurred since 1975, at 0.15-0.20C per decade. Research says mean temperatures across India, on the other hand, have risen by more than 0.5C from 1960 to 2009.

“The heat situation seems to have got worse in the last two years,” says Aditya Valiathan Pillai, an associate fellow at the Centre for Policy Research. When his team wanted to find out how governments at different levels are responding to heat in terms of executing heat action plans, they could track only 37 across the country. Out of that, only two mentioned how the plan would be funded.  Eight of them said that they leave it to the departments to find the funding.

“The biggest weakness is lack of funding,” says Pillai. “If there is a scheme that’s financed, then it’s more likely to be implemented.”

He says they’re working on putting out policy fixes, both short-term and long-term, that can help heat plans be more effective: For example, “National adaptation fund on climate change is meant for these kinds of things. In addition, closely-related schemes such as PM Awas Yojana, Kisan Yojana, MGNREGA mission can be tapped to provide funds.

Moreover, he says, “We need a national repository where all the heat action plans are deposited and made accessible to the public.”

The most important component of addressing heat disaster is “you should know where your most vulnerable people are.”  Heat is a multi-sectoral problem affecting people from different walks of life—farm labour, construction workers, street vendors and small business people. It spans multiple localities, neighbourhoods and communities.

“It is not enough to know what needs to done but also where it needs to done,” says Pillai. Out of 37 plans they saw, only two had vulnerability assessments.  Focusing on high-risk populations could reduce heat deaths significantly. In addition, without robust estimates of heat deaths, “you’re flying blind.” Mortality and morbidity data help in defining temperature thresholds for heatwaves, in allocating meagre resources such as ambulances, ice packs, cooling centres and others judiciously.

Abnormally high temperatures from the second week of March 2022 onward contributed to the loss of wheat yield, down from 110 million metric tonnes (MMT) to 99 MMT, according to the a United States Department of Agriculture report. Power crisis hit the country. We don’t yet know what’s happening to biocenosis in India due to heat.

The kind of heat we're talking about will affect everything—the physical body, the land and fertility, the economy and society as a whole. Already, it defines India in many ways and in years to come it will become even more of a marker. It is not a comforting thought.