New Delhi — Shiv Shankar, 54, works all day on a construction site in the blistering New Delhi sun. He can't even think of taking a day off to avoid the deadly heat wave that has gripped India's capital and much of the country's north since late March. That would mean losing a day's wages, and his family of four simply can't afford it.
Hundreds of millions of workers in India and Pakistan spend every day outside, without the option of avoiding even the hottest hours of the day. Those workers may face increasing life or death choices about going to work, as scientists say climate change is making deadly,like the one hitting northwest India and Pakistan right now 100 times more likely to occur.
A report published this week by the U.K. government's Meteorological Office says climate change has increased the chances of heat waves hitting the region from once every 312 years, to once every 3.1 years.
"And by the end of the century… this will increase to once every 1.15 years," the study concludes.
In recent weeks, temperatures over 120 degrees Fahrenheit have scorched parts of India and Pakistan, killing dozens of people,, increasing the demand for energy while triggering electricity blackouts, forcing authorities to shut schools, and prompting officials to warn people to stay indoors.
New Delhi hit 120 degrees on Sunday.
"I have seen heat waves before, but this is something entirely different," Shankar told CBS News on Thursday. "I drink a lot of water to keep myself hydrated, and take small breaks off work."
Shankar migrated from the central Indian state of Uttar Pradesh to New Delhi years ago to work in construction. He sends most of his earnings home so his wife and two teenage children can put food on their table.
Scientists say prolonged exposure to extreme temperatures poses a risk of fatal heatstroke and can impact the functioning of vital organs including the heart, lungs, kidney, liver and brain.
Authorities do urge workers to take time off on the hottest days, but as laborers only get paid if they're on the job, that can mean a crippling loss of income for millions of families like Shankar's.
Between 2001 and 2020, India lost around 259 billion hours of labor per year due to the impacts of extreme heat, according to a Duke University study published in January. That translates to a loss of about $624 billion to India's economy, and a much more literal impact on families that live hand-to-mouth every week.
One of the lead researchers behind the Duke study, Luke Parsons, told CBS News there's no doubt that rising global temperatures mean "more people will be exposed to uncomfortable and unsafe levels of heat more and more frequently unless they are able to move inside and cool themselves."
"In both India and the U.S., this means that those who are the most vulnerable — for example, the elderly, and often those who have jobs that force them to work outside or those who are too poor to afford to purchase and run air conditioning — will be the most impacted," Parsons said.
Among them are the estimated 85,000 bicycle rickshaw drivers in Delhi.
"I earn 300 to 400 rupees (about $5) a day," Shiv Kumar Mandal, a rickshaw driver in Delhi's shopping district, told CBS News on Friday. "What do you mean, 'why am I working in this heat?' If I don't work, we will die of hunger."
Parsons said people like Mandal and other laborers "are often forced to choose between their health and safety, and economic well-being, which is not a good choice to have to make."
And the science points to it getting worse.
"There is no doubt that in future the heat waves will occur more often, last longer and cover larger parts of the Indian subcontinent," Vimal Mishra, a climate scientist at the Indian Institute of Technology in Gandhinagar told CBS News earlier this month.
Forcing people to decide between working in dangerous conditions or going hungry is only one impact of the heat waves in the region.
"They are going to affect water availability, agriculture, businesses and energy demand," Mishra told CBS News.
The current heat wave in India has already had a global impact, helping to send the price ofsoaring to a record high last week after India banned exports of the crop, which has been badly damaged by the dry, hot conditions.
Scientists say it's evidence of the fact that, while India and other developing nations are more vulnerable to the effects of climate change, they won't suffer alone.
"This is not going to stop in India," Dr Anjal Prakash, a climate scientist and lead researcher with the United Nation's Intergovernmental Panel on Climate Change (IPCC), told CBS News. "This will eventually hit the backyard of the countries who created this problem for us."
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