New Delhi — It’s still spring but hundreds of millions of people across South and Southeast Asia have already faced scorching hot temperatures. The summer heat has arrived early, setting records and even claiming lives, and it’s expected to get much worse through May and June as summer actually begins.

At the beginning of May, severe heat waves were already blamed for nearly three dozen deaths across the vast region. Schools have been forced to close weeks ahead of summer vacations and huge swaths of new crops have withered in parched farmland.

Scientists warn of wide-ranging impacts in some of the world’s most densely populated regions, and they’re urging governments to take immediate action to prepare for the impact of climate change and do whatever is possible to mitigate human-caused global warming.

What’s happening, and where?

Several parts of India recorded maximum temperatures over 110 degrees Fahrenheit last month. On April 21, people in the eastern city of Bhagdora sweltered as the mercury touched 114.8 degrees. 

The India Meteorological Department (IMD) on Tuesday issued a “red alert” warning for the eastern and southern states of Andhra Pradesh, Bihar, West Bengal and Odisha, where temperatures have been soaring since mid-April. The IMD warned the heat wave was set to get worse before it gets better.

At least two people died in the southern state of Kerala due to suspected heat stroke over the weekend. Two other deaths were blamed on the heat in the eastern state of Odisha earlier in April.

The scorching temperatures are hitting India right in the middle of an ongoing six-week general election — in which nearly a billion people are eligible to vote — making campaigning and voting challenging.

Authorities in neighboring Bangladesh were forced to close all schools twice over the last two weeks amid the heat wave, and temperatures soared to nearly 110 degrees on Monday. 

Several areas in Myanmar have recorded record high temperatures around 115 degrees, with a much higher heat index. The heat Index is a measure of what the temperature actually feels like, taking into account humidity, wind speed and other factors.

The heat wave conditions have been brutal in Southeast Asia, too. In the Philippines, authorities closed thousands of schools as vast areas of the country experienced drought and temperatures up to 111 degrees — unprecedented for the region in early April.

In Thailand, authorities have urged people to remain indoors when possible with 30 deaths already blamed on heat stroke this year. In the capital Bangkok, authorities said the heat index Thursday was an “extremely dangerous” 125.6 degrees. 

In Vietnam, where temperatures passed the 111 degree mark, the national weather agency warned of the risk of forest fires, dehydration and heat stroke.

“Thousands of records are being brutalized all over Asia, which is by far the most extreme event in world climatic history,” weather historian Maximiliano Herrera said in a social media post last week.

What’s causing the extreme heat?

Scientists are divided over the impact of the ongoing El Niño weather phenomenon, but many believe the temporary warming of the central Pacific, which has altered weather patterns worldwide for years, has made things much worse this summer in South and Southeast Asia.

“I think it’s a mix of El Niño, global warming and the seasonality,” Prof. Raghu Murtugudde, a climate scientist at the Indian Institute of Technology Mumbai, told CBS News. “El Niño is transitioning to La Niña. This is the time when the maximum warming happens towards the Indian Ocean. So, all these things are basically adding steroids to the weather.”

Murtugudde noted that the El Niño phenomenon was already established by March 2023, so last year’s heat waves were also due to a combination of global warming, El Niño and the annual cycle, but he said this year was worse because of the transition to the La Niña pattern.

Not all climate scientists agree, however, about El Niño’s impact.

“We saw heat waves even last year and it wasn’t blamed on El Niño,” Prof. Krishna AchutaRao, a scientist at the Indian Institute of Technology Delhi’s Centre for Atmospheric Sciences, told CBS News.

Last year, severe heat waves killed more than 100 people in India and Pakistan alone in April and May, again destroying crops and affecting millions of people.

“Just like this year, last year the heat wave extended from parts of India to Bangladesh and Myanmar, and all the way to Thailand. This year it went further east, into the Philippines. So, it’s the same pattern,” AchutaRao said. “I do not particularly buy into this that El Niño is the cause.”

Most experts do agree, however, that climate change is one of the major causes of the brutal heat hitting Asia this spring, and scientists said last year that climate change was making heat waves 100 times more likely to occur.

AchutaRao, along with other scientists working with the World Weather Attribution organization, have compiled and analyzed data on last year’s heat waves in the region and the dozens of natural disasters that came with them in Laos and Thailand. The team “concluded that [extreme weather] events like those were not possible without climate change.”

“Climate change is exacerbating the frequency and severity of such events, profoundly impacting societies, economies, and, most importantly, human lives and the environment that we live in,” Ko Barrett, Deputy Secretary-General of the World Meteorological Organization said last month.

Temperatures went through the roof globally in 2023, making it the hottest year ever recorded. The United Nations weather and climate agency said Asia was warming at a particularly rapid pace — making extreme weather events such as floods, major storms and cyclones more frequent and more dangerous.

The poor will suffer most

Around the world, countries have tried to manage the impact of extreme weather events through early warning systems and advisories, but Asia’s large, poor populations will bear the brunt of the impact of the heat waves, Murtugudde told CBS News.

The heat is likely to continue inflicting widespread crop damage, further impacting the lives of farmers who’ve already faced increasing challenges in recent years — to the extent that hundreds of thousands staged massive protests in India to demand government help.

Many national governments restrict outdoor activity in a bid to prevent deaths during extreme heat events, which has an outsized impact on manual laborers in the construction sector — a huge part of Asia’s fast-developing economies.

Scientists and environmental activists across the globe have consistently urged nations to cut greenhouse gas emissions, warning it is the only way to slow the rate of global warming. Until that happens, experts fear the death toll will keep rising, and millions of people will face a dire decision with every new heat wave: Work in dangerous conditions, or go to bed hungry.