An increased scorch in summer heat in India is about to cause a big jump in heatwave death rate, researchers at the University of California in Irvine warned.

Although the 0.5 rise on the average temperature might seem quite modest, but over the past 50 years it has led to almost a 150% hike in heatwaves and killed almost 100 people.

But India, along with other Asian nations is now on its way to a temperature rise to between 2.2 and 5.5 degrees Celsius by the end of the century, which is likely to cause a rise in death tolls as well.

“I was taken aback by how large the increase in the likelihood of these mass mortality events was with a modest increase in temperature,” said Steven J. Davis, an earth systems science professor at the university and one of the authors of the report, published in the journal Science Advances.

“Even under the lower global warming scenario, you still see temperature increases of 2, 3 or more degrees. We’re looking at a small temperature increase and still seeing a big increase in heatwave deaths. It seems pretty shocking,” he said on an interview over the telephone.

Not only Asia, temperature rises are expected throughout much of the globe by the end of this century, and that “may make low-latitude developing nations in the Asian subcontinent, the Middle East, Africa and South America practically uninhabitable during the summer months”, the report noted.

A study based on temperature and heat death data in India between 1960 and 2009 said that in the years since 2009 heatwaves in India killed more than 1,300 people in 2010, 1,500 in 2013, and 2,500 in 2015 as summers grew hotter.

According to the study, access to electricity, particularly on air conditioning can help curb heat deaths. But about 1/4th of India’s population have no electricity at all, and another quarter earn less than $1.25, making electricity a luxury they can’t afford.

The biggest victims of heatwaves are the poor, the study suggests. Not only because they cannot afford electricity, but because they also have a shortage of clean drinking water and shelter from the excess heat. Which causes health conditions that are triggered by high temperatures and limited medical care.

The Indian government is trying its best to make electricity more accessible across the nation, with a goal to connect all homes by 2019. But with a population above 1.3 billion, that can be a tough job.

“Access to air conditioning and electricity is key to address heat-caused mortality and that requires significant investment,” said Amir AghaKouchak, one of the report’s authors. “India’s government is trying, they’re doing great. But the population is also growing. It’s not an easy challenge.”

Some Indian cities have taken precautions to cope with the rising heat, providing emergency cooling centers, cancelling leaves for doctors this summer, and broadcasting warnings when increased heats reach an alarming level.

“India is quite proactive in climate-related education and outreach,” AghaKouchak said by telephone. “Awareness is the low-hanging fruit” in dealing with the problem, he added.

A heatwave that’s still on the go has already killed nearly 20 people in Gujarat & Orissa this summer.

Dealing with global warming has recently become even more difficult for developing countries like India, as the US has withdrawn from the 2015 Paris Climate Accord.