Anthropogenic Climate Change

second month

This week, temperatures are soaring to dangerously high levels. They topped 110 degrees in the Indian capital of Delhi on Thursday. The city of Nawabshah in Pakistan hit 117.5 degrees (47.5 degrees Celsius) — 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 one step higher at “heat alert.”

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

Most of India and a large area of Pakistan spent Thursday scorching under temperatures ranging between 104 to 113 degrees (40 and 45 Celsius). Between the two countries, nearly 1 billion people roasted under these extraordinary temperatures.

More than three dozen locations in India recorded temperatures of 113 degrees (45 Celsius) or greater, including the sprawling capital of Delhi, where readings rose as high as 115 degrees (46 Celsius) at the sports complex. Its official high was 110.3 degrees (43.5 Celsius), its highest April temperature in 12 years, according to the India Times.

The heat may escalate further Friday and Saturday, with little relief at night.

Temperatures of 110 degrees (43 Celsius) or higher are expected Friday throughout central India, including in the city of Nagpur. Another zone of similar temperatures is anticipated in north and east India from near Delhi, running southeast through much of Uttar Pradesh, and toward the border of Jharkhand nearer the coast.

Similar conditions are likely Saturday and Sunday, with some slight easing thereafter.

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.

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.

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.

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,” [[https://twitter.com/hausfath/status/1519407921058119680? tweeted]] Zeke Hausfather, a climate researcher at Stripe, a global technology company. “On our current emissions trajectory (SSP 2-4.5) 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.