The analysts at ClimaMeter said the intense and prolonged heat wave India endured in May was a result of the naturally occurring El Nino phenomenon -- unusual warming of the ocean surface in the central and eastern tropical Pacific Ocean -- and the rapidly increasing concentration of greenhouse gases -- primarily carbon dioxide and methane -- in the atmosphere.

The researchers analyzed how events similar to the high temperatures in India's May heatwave changed in the present (2001-2023) compared to the past (1979-2001).

"The temperature changes show that similar events produce temperatures in the present climate at least 1.5 degrees Celsius warmer than what they would have been in the past over a large area of the region analyzed. The precipitation changes do not show any significant variations," the analysis read.

ClimaMeter's findings underscore that heatwaves in India are reaching unbearable temperature thresholds because of fossil fuels burning, said Davide Faranda of French National Centre for Scientific Research.

"There are no technological solutions for temperatures approaching 50 degrees Celsius. We should all act now to reduce CO2 emissions and avoid exceeding vital temperature thresholds in large areas of the subtropics," he said.

Gianmarco Mengaldo of National University of Singapore said the findings show the complex interplay between natural variability and climate change, with the latter playing an important role in critical synoptic-weather-pattern changes in tropical and subtropical regions that may significantly aggravate heatwaves in the near future.

The world is witnessing weather extremes under a combined effect of the 2023-24 El Nino and human-caused climate change.

This May was the warmest May ever and the last 12 consecutive months -- June 2023 to May 2024 -- have broken temperature records for each corresponding month, according to the European climate agency Copernicus.

Northwest India and parts of the central region reeled under a punishing heatwave in May which tested India's disaster preparedness, with several states reporting heat-related deaths.

There are concerns that heat waves in April and May have played a role in the lower-than-usual voter turnout during the seven-phase general elections in India that began on April 19 and ended on June 1, the second longest after the 1951-52 parliamentary elections.

According to the Central Water Commission, water storage in 150 major reservoirs in India dropped to just 22 per cent of their live storage this week, exacerbating water shortages in many states and significantly affecting hydropower generation.

The intense heat has already driven India's power demand to a record 246 gigawatts, with air conditioners and coolers in homes and offices running at full capacity.

India recorded nearly 25,000 suspected heat stroke cases and 56 deaths due to heat-related illnesses from March to May, PTI reported earlier, citing data from the health ministry.

According to data compiled by the National Centre for Disease Control (NCDC), 46 of these deaths were recorded in May alone (till May 30). Between May 1 and 30, 19,189 suspected heat stroke cases were reported in the country, it said.

The data does not include deaths from Uttar Pradesh, Bihar, and Delhi, and the final numbers are expected to be higher, a source said.

Severe heat waves have impacted a large number of people in parts of India for three consecutive years, affecting health, water availability, agriculture, power generation, and other sectors of the economy.

The heatwave in May saw several places across the country, including Assam, Himachal Pradesh, and Arunachal Pradesh, recording their all-time high temperatures. Parts of India saw record-breaking maximum temperatures in April as well.

Similar heatwaves could occur once every 30 years, and these have already become about 45 times more likely due to climate change, 'World Weather Attribution', a group of leading climate scientists, said last month.

Experts say those working outdoors, the elderly, and children are at higher risk of heat exhaustion and heatstroke.

According to a World Bank report, India could account for 34 million of the projected 80 million global job losses from heat stress-associated productivity decline by 2030.

In the absence of adequate cold-chain infrastructure, extreme heat can cause major damage to fresh produce. Studies show India faces food losses worth USD 13 billion a year, with only four percent of fresh produce covered by cold chain facilities.