Standing by vast, ash-colored coalfields, miner Rabi Behera expressed few doubts about the job at hand. To cope with increasingly brutal temperatures, India has to keep its power grid standing— and for now that means digging up ever expanding quantities of the dirtiest fossil fuel.

“It’s hard to survive without electricity during the summer,” he said, giant trucks rumbling past in clouds of black dust. “Our production target is raised every year. Every year we’re producing more coal.”

So far, this year has been less blistering than 2022, when temperatures in New Delhi climbed past 49C (120F), but February still broke records, April saw lethal conditions and forecasters issued warnings for this month, when pre-monsoon heat tends to peak. Extreme temperatures are increasingly frequent, and that’s driving electricity consumption surges, which in turn push up demand for fuel from vast pits like Gevra’s in the eastern state of Chhattisgarh, where Behera works — soon to become the largest coal mine in the world.

Wealthy nations are, by and large, moving away from coal, the single largest contributor to climate change, according to the International Energy Agency. But even with considerable advances in renewable energy, the world’s most populous country still relies on the black stuff for roughly three-quarters of power generation, and will need it for years to come. The fuel is relatively cheap, and, crucially for an energy-importing economy, readily available domestically.

As a result, India is now the third-largest emitter of greenhouse gases, even if it still lags China and the US, and per-capita figures remain below the global average. A vast, climate-vulnerable nation is making its own predicament worse, leaving hundreds of millions of its workers caught in a vicious heat cycle — with all the health and economic productivity costs that come with toiling in sweltering conditions. A 2020 McKinsey Global Institute report estimated that as of 2017, heat-exposed work contributed to about half of India’s gross domestic product, and a third of GDP growth.

It’s not just about rising mercury. The combination of heat and humidity may make parts of India some of the world’s first uninhabitable places. At high humidity even relatively modest temperatures can compromise the body’s ability to cool itself by sweating. This can lead to fainting, heat stroke and heart attacks.

“Heat is not foreign to most countries in South and Southeast Asia. However, at present level of global warming, it is just going beyond the survivability limit,” said Fahad Saeed, an Islamabad-based scientist with Climate Analytics. “The heat is incredibly serious and points to the need for us to reduce emissions as fast and as hard as we can.''

Miners like Behera find themselves at both ends of the problem.

He helps dig coal for state-owned Coal India Ltd, one of the largest producers globally. He said he sees the benefit of strong demand and his family enjoys the appliances electricity can power. He is also among those risking the worst of the consequences, laboring daily in a black, shade-free moonscape. Unlike truck drivers who can take refuge in air-conditioned vehicles, Behera, a supervisor, spends his days outside, in a region where temperatures have topped 49C.

Behera pointed out a small kiosk, insulated with wooden sheets, where workers can rest or eat in the shade, one of the measures the company has taken to mitigate the heat. Workers in hard hats and sunglasses walked past, their faces covered with scarves to protect against the heat and debris. Most employees carry oral rehydration salts, just in case. An ambulance is always on stand-by.

Temperatures always spike before the monsoon hits around June. But blistering, life-threatening levels like those reached in 2022, and tested again this year, are becoming more common. A changing climate has made extreme heat 30 times more likely in India.

There are consequences for agriculture in a country that has 1.4 billion people to feed, already frets about import bills and can roil world markets. Last year, severe heat forced the second-biggest producer of wheat to ban exports, fueling fears about global shortages as the war in Ukraine upended supply chains.

In the eastern state of Odisha, dairy farmer Manoj Kumar Behera described falling milk output as even mixed breeds among his 25 cows and calves struggle to tolerate the heat. With intermittent electricity supply, he has few options but to deal with the losses.

“When we ask about power cuts, we are told it’s happening due to abnormal demand for electricity during summer months,” he said, as his workers fed the cows nearby. “Sometimes when it gets too hot in the shed, we have to bring the cows out to rest under the trees.” Production, he said, falls by close to a third.

The impact is far wider, though, threatening overall productivity, long-term health and even survival, as hundreds of millions are exposed to extreme conditions — a greater proportion of the population than anywhere else globally. Heat may lower the quality of life for almost 600 million Indians by 2100.

That means the myth that India, a hot country, can cope with extreme heat must be dispelled, said engineer and computational social scientist Ramit Debnath at the University of Cambridge, who researches climate misinformation and last month published a study on the impact of heat on development.

“I received comments, including from doctors, saying Indians have their own way of coping with heat wave, so, it's not a very big problem,” he said. “The notion that Indians are more resilient to heat than people elsewhere is misinformation.”

READ: How Extreme Heat and Humidity Test Survival Limits: QuickTake

Awareness is growing. The government has developed heat action plans, providing guidelines for state, district and city authorities on how to respond. Prime Minister Narendra Modi led a meeting in March to review preparedness for hot weather conditions.

But heat waves are not explicitly among the disasters eligible for relief under the National and State Disaster Response Funds, and a study of state- and city-level heat action plans by the Centre for Policy Research think tank found significant gaps.

The blueprints for New Delhi, a metropolis of 33 million which smashed temperature records last year, have yet to be released. The state government directed a request for comment to the local disaster management authority, which directed queries to the pollution control board. The pollution control board did not comment.

Meanwhile, official definitions of heat waves still focus only on temperature thresholds — not on impact of high humidity or the link to smog. “Heat waves can intensify air pollution and that's simple physics: pollutants won't be able to escape because of the heat,” said Ronita Bardhan, an architectural engineer at the University of Cambridge who researches sustainability and also worked on the heat study.

READ: A Billion Air Conditioners Will Save Lives But Cook the Planet

Companies have largely been left to deal with the problem as they see fit. Food delivery startup Zomato Ltd. provides rest stops for riders to take a break between deliveries, offering clean drinking water, first-aid kits and access to washrooms. Other e-commerce firms provide sports drinks or replace less breathable uniforms with material suited for hot weather.

But there are also pressures to meet targets. In the Talcher coalfields in Odisha, run by a unit of Coal India, a local government directive means outside work should stop in the middle of the day, to prevent heatstroke. But work in the opencast mines rarely does, according to workers who asked not to be identified as they are not authorized to speak to the media. Some coal mine officials said they simply do what ever it takes to meet production targets.

Mahanadi Coalfields Ltd, the unit of Coal India, said the order does allow coal mining to continue as it’s linked to essential services, specifically power supply. The company tries to ensure the safety of field workers by limiting their exposure to the sun and maximizing output during cooler times of the day or at night. “It is possible that couple of workers may not be aware of the order. However, this does not mean we are not conscious of our duties to protect our workers,’’ it said in response to queries.

The trouble is that India’s power demand is growing. Green development, climate finance and sustainability have been a priority for its Group of 20 presidency this year, but coal will remain a major part of India’s power sector in the coming decades. The Central Electricity Authority estimates it will account for 54% of generation in 2030, and the country is still building coal-fired plants.

“This will delay the amount of emissions that could have been cut off, and that’s a major concern — not just for India but for across the world,” said Bardhan. “We are not saying that India needs to stop using coal completely at this point. But probably phasing out and understanding the opportunities and potential in renewables, understanding where the investments can happen… those areas need more discussion.”

The opportunity should appeal as multilateral lenders and even wealthy nations and capital markets push cash towards the energy transition. BloombergNEF calculates that India will need $12.7 trillion in supply and demand-side investment to become net zero by 2050. The country targets to reach net zero by 2070.

Modi’s government raised its goals for clean energy capacity last year. India is offering incentives to add more solar or wind power and aims to become a global hub for production of green hydrogen and green ammonia. But New Delhi has also opposed international efforts to set firm deadlines to phase out the use of coal.

Today, with the monsoon still days from making landfall further south, the news is good mostly for air-conditioner sellers like Vishnu Moorarka, sitting in his electronics shop in Bilaspur, a city on the Chhattisgarh plain, about two-hour drive from the Gevra mine. He has been anticipating the start of nautapa in late May, a nine-day period in the Hindu calendar that’s traditionally held to be the hottest of the season.

“We have stocked up inventory in expectation of high demand,” Moorarka said, a cluster of air-conditioner units neatly stacked behind him. His staff haven’t been allowed to take time off, he said, and his eyes are constantly on his phone — for weather alerts.

After a long day at the Gevra mine, supervisor Behera is less optimistic. “It’s getting hotter than earlier. Trees are being cut, industries and mines are coming up,” he said, at home with his two children. “It will only rise from here.”

--With assistance from Sreeja Biswas and Spe Chen.