New Delhi: The city feels like it is on fire. The heat comes off the road in blistering waves, and the water that flows from the cold tap is too hot to touch. Daytime temperatures have hit 44 degrees and often do not fall below 30 at night. A giant landfill on the outskirts of the capital spontaneously combusted a week ago, and the 17-storey-high dump that contains millions of tons of garbage continues to smoulder, worsening the city’s already dangerously polluted air.

Daily power outages driven by a surge in demand for electricity have resulted in blackouts as long as eight hours in some parts of India, while coal stocks — the fuel that accounts for 70 per cent of the country’s electricity generation — are running low, prompting warnings of a fresh power crisis. The northern wheat crop is scorched. It was the hottest March in 122 years. Spring just didn’t happen, and those extreme temperatures continued into April and May (though they are predicted to ease this week). Still, it’s not until June that the monsoon is expected to arrive and provide any kind of relief.

What’s most alarming about this heatwave is that it’s not so much a one-time ordeal as a taste of things to come as the effects of global warming push India and its neighbours to levels where the climate is a core threat to human health.

The most worrying weather measurement is not the heat typically reported in forecasts but the wet-bulb temperature, which combines heat and humidity to indicate how much evaporation can be absorbed into the air. At wet-bulb temperatures above 35 degrees Celsius, we become unable to reduce our temperature via sweating and will suffer potentially fatal heatstroke after only a few hours, even with shade and water. Similar effects can result for those working outdoors when wet bulb temperatures exceed 32 degrees, and measures as low as 28 degrees caused tens of thousands of deaths in the European and Russian heatwaves of 2003 and 2010.

Humidity falls as temperature rises, so such events were once thought to be extraordinarily rare. One 2018 study concluded that the most severe temperatures of close to 35 degrees “almost never occur in the current climate”. In fact, closer analysis of data from weather stations done in 2020 suggests they’re already happening relatively frequently, particularly in the heavily populated belt from the Persian Gulf through Pakistan and northwest India.

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Just 12 per cent of India’s 1.4 billion citizens have access to airconditioning, which means hundreds of millions of people are simply unable to cool themselves when their bodies reach the point of heatstroke. It’s a situation mirrored in neighbouring Pakistan, which is experiencing similarly catastrophic heatwave conditions. Daily wage earners, who toil in the fields, work in factories and construction, sweep streets and build roads, have no escape.

Multiple regions of India have already been edging close to critical wet-bulb temperatures over the past week, according to government data, though the maximum humidities haven’t necessarily been occurring at the same time as the peak temperatures.

The risk is that, even if the most hazardous levels are avoided in the current heatwave, each hot season is a fresh roll of the dice on whether a freak event will occur that will lead to vast numbers of deaths. The odds lengthen with each passing year. The world is currently in the grip of a La Nina climate cycle, which typically brings cooler summer weather to India. When that next flips to El Nino, the risks will ramp higher still.