Heat wave breaks monthly records in India and continues to build

The Times of India reported Delhi clinched its second hottest April in 72 years Friday with an average high temperature of 104 degrees (40.2 Celsius).

The city of Nawabshah in Pakistan hit 117.5 degrees (47.5 degrees Celsius) Thursday — the hottest temperature in the Northern Hemisphere this year so far.

The heat wave has heightened the fire danger in recent days, threatened crop yields and even accelerated melting of some glaciers. While this part of the world is no stranger to extreme heat, scientists say conditions have been worsened because of climate change.

“Heat waves happen more frequently now and they are spread around throughout the year,” said Amir AghaKouchak, a professor at University of California at Irvine, in an email. “This is the new normal and most likely it will only get worse in the future unless we take serious actions.”

The India Meteorological Department has placed much of that nation under a “heat watch” through the weekend, with some locations like Madhya Pradesh in the center of the country are at one step higher at “heat alert” through Saturday.

Temperatures in this episode are expected to peak over the weekend, although the hot temperature regime over the subcontinent seems entrenched, with little meaningful relief in sight.

On Friday, more than 50 locations in India recorded temperatures of 111 degrees (44 Celsius) or greater, including the sprawling capital of Delhi, where readings rose as high as 115.1 degrees (46.2 Celsius) at the sports complex. The city’s official high was 110.3 degrees (43.5 Celsius) both Thursday and Friday, its highest April mark in 12 years.

Gurgaon, just southwest of New Delhi, broke its monthly April record on Thursday and again on Friday, when it hit 114.6 degrees (45.9 Celsius), shattering its previous record of at 112.6 degrees (44.8 Celsius) in 1979.

Lucknow, the largest city in the northeastern state of Uttar Pradesh, surpassed 113 degrees (45.1 Celsius) setting a new April record Friday. April records were also set in in the northeastern state of Uttar Pradesh where the city of Banda reached 117.3 degrees (47.4 Celsius) while Prayagraj hit 116 (46.8 Celsius).

More temperature records are expected to fall, as the heat may escalate further Saturday and Sunday, with little relief at night.

According to Maximiliano Herrera, an expert on world weather extremes, the highest April temperature in India is 118.9 degrees (48.3 Celsius), reached in Barmer during 1958. Nawabshah, Pakistan, about two hours inland from the Arabian Sea, hit 122.4 degrees (50.2 Celsius) four years ago.

It’s probable that Pakistan ends up with the highest temperatures overall. Some locations north of the capital of Karachi could hit 120 degrees (49 Celsius) or higher through the weekend. Forecasts for Jacobabad, known as one of the hottest cities on Earth, are as high as 122 degrees (50 Celsius), which could test major records.

The intense heat has caused significant power disruptions, described as the worst in years. Much of rural India lacks access to air conditioning. The unprecedented early-season heat waves are causing major health concerns in a country accustomed to the perils of hot conditions.

“The unfortunate reality is that people who are more vulnerable are the ones who will be impacted the most,” AghaKouchak said. “Lack of access to air conditioning, which is more common in poor and underserved communities, significantly increases the likelihood of heat stroke and heat wave caused mortality.”

Even without extreme heat waves, AghaKouchak found that just moderate increases in temperature can drastically increase mortality rates. Over the past five decades, around 0.92 degrees (0.5 degrees Celsius) of warming has increased the probability of heat-related mortality events of more than 100 people by 146 percent.

Most of those hazards are due to an increase of nighttime temperatures. AghaKouchak said temperatures typically tend to dip at night, providing a chance for our bodies to cool down. Without this cool-down, the prolonged heat increases the risk of heat exhaustion, cramps, strokes and even death.

“While we typically look at daily temperature extremes, nighttime temperatures are also really important for human health. … Nighttime heat waves have also increased significantly in densely populated areas of India,” AghaKouchak said. He and his colleagues previously found that the hottest nights from 1981-2013 have warmed by 0.92 degrees (0.51 degrees Celsius) per decade.

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India’s prime minister, Narendra Modi, also said the elevated temperatures have increased the risk of fires across the country. Just in the past few days, satellites have detected a large increase in fire hot spots, especially in the northern part of the country. One fire at a landfill outside of New Delhi spewed toxic fumes, prompting a nearby school to shut down Tuesday.

Waves of relentless heat are also impacting the harvest. Wheat arrivals have been reported as running 20 percent below 2021 values in parts of the country this year. The decrease is mainly due to consistent temperatures above 104 degrees (40 Celsius) across Punjab — a breadbasket of the country — during the growing season.

A drop in yield is largely due to crops that matured too quickly and have shriveled grains because of the early heat. It comes at a time when India was hoping to fill some of the gaps in the world market, like those created by Russia’s ongoing war in Ukraine.

There are also concerns that the heat wave is rapidly melting glaciers, which might lead to flash and river flooding, according to the Pakistan Meteorological Department.

While India is often exposed to intense heat episodes, research shows the frequency, duration and intensity has increased as global temperatures rise.

A February study revealed that human activity played a larger role than natural causes, stating “anthropogenic factors have cause a twofold increase in the occurrence probability of severe heat waves in central and mid-southern India during twentieth century.” The risk of heat waves is projected to increase tenfold during the 21st century under some future climate change scenarios as well.

“The extreme heat wave hitting India this week comes on top of 1C warming that country has already experienced,” tweeted Zeke Hausfather, a climate researcher at Stripe, a global technology company. “On our current emissions trajectory (SSP2-4.5) India is headed for around 3.5C warming by the end of the century.”

Hellacious high pressure “heat domes,” like the one that has persisted over India in recent months have been found to be more common and more intense than in the past. Similar record-breaking temperature setups occurred in the Pacific Northwest during 2021, among other recent instances across the globe.

Temperatures tend to peak in India during April and May, or just before the rainy season — a seasonal shift in winds called the monsoon — gets underway. Cloudier and rainier conditions of the monsoon typically sweep north and west out of the Indian Ocean by late May and into early summer, lasting through early fall.

While readings are expected to drop somewhat after this weekend, there are signs of a resurgence thereafter.