Climate change made India’s April heatwave 45 times more likely: Study

The heatwave in India was made 45 times more likely due to climate change and recurrence of extreme heat incidents are likely as the global temperature goes up from the current 1.2 degrees Celsius towards 2 degrees Celsius, according to a study by the World Weather Attribution (WWA).

The findings are part of the WWA’s report on heat waves in Asia based on the quantification of the effect of human-caused warming on the extreme temperatures.

The report, authored by seven scientists and reviewed by six others, comes on the back of similar findings for the year 2022 and 2023, with the authors pointing to the influence of the rise in global mean surface temperature on the extreme heat.

The scientists analysed weather data along with peer-reviewed models to compare how the heatwave incident has changed between today’s climate of 1.2 degree of global warming and the cooler pre-industrial climate. Three sets of time series was taken for different regions of Asia: three-day average daily maximum temperature in March-April in West Asia; 15-day averaged daily maximum temperatures annually in the philippines and average April temperatures in South Asia, from India to Combodia.

WWA’s 2022 study on dry heat at monthly temperatures and the 2023 study focused on humid heat and extreme temperatures at short timescales. The analysis showed a 30-fold increase in event probability and a temperature rise of around 1 degree Celsius in average daily maximum temperatures. Similar was India’s 2024 summer.

“The synthesis of observation reveals a strong climate change signal... The 30-day heatwave in South Asia, including India, can be expected to occur about once every 30 years. “However, they have already become about 45 times more likely and 0.85 degree Celsius hotter due to climate change,” the study said.

The researchers acknowledged the links between El Nino Southern Oscillation (ENSO) and extreme weather events but said the larger spatial scale means “the change in ENSO is not expected to influence global mean surface temperature-driven trend in April mean temperatures’.

“While high temperatures are the norm across Asia during April, the increasing risk of dangerous heat, particularly in rapidly growing cities, highlights the critical need for heat planning that protects vulnerable groups,” the researchers said.

Friederike Otto, Senior Lecturer in Climate Science at Grantham Institute - Climate Change and the Environment, Imperial College, London, said the additional heat was driven by emissions and those vulnerable suffer the most. “The main story is absolutely the same: climate change makes these heat waves much more likely, it makes it longer and much more intense. It’s always those who are most vulnerable who will pay the price and sometimes with their lives,” she added.

Mariam Zcharia, Researcher at the Grantham Institute, said unless the world takes massive, unprecedented steps to reduce emission, extreme heat will lead to even greater suffering in Asia. “Our study is consistent with our previous findings. Looking into the future in a 2 degree Celsius world, the heatwave incidents will be about 7 degree Celsius hotter,” she said.

The study said urgent attention is required to enhance cross-sectoral collaboration and prioritise immediate relief measures during heatwaves to mitigate recurrent impacts and safeguard vulnerable populations effectively. The current efforts to prepare for extreme heat incidents, accelerated and expanded action is needed to protect those most vulnerable, it pointed out.