Scorching heat, flash floods, disappearing spring: India's weather story


New Delhi, Jun 2
Sweltering heatwave in north India that have caused scores of deaths, floods and landslides in the North East that have affected lakhs of people, a spring season that suggests it could soon "disappear" from the calendar—extreme weather events in the first five months of 2024 have got everyone questioning: where is all this headed ? Despite having made predictions to this effect, climate scientists acknowledge that the temperatures this summer, including the outlier 52.9 degrees Celsius in Delhi, are "alarming, though not surprising".
"This could be the worst summer in the last 120 years, at least for north India. Never have temperatures gone so high—more than 45-47 degrees Celsius—for such a vast region, which is also densely populated. This is a record in itself," Vimal Mishra, Vikram Sarabhai Chair Professor, Civil Engineering and Earth Sciences, IIT Gandhinagar, told PTI.
The temperatures, "similar to those in Africa's Sahara desert," are "far beyond expectations" by at least three or four degrees, according to Mishra.
Earth system scientist Raghu Murtugudde, Professor at IIT-Bombay, told PTI this was due to the combined effect of multiple phenomena-climate change, El Nino and the water vapour released by Tonga's Hunga Tonga volcanic eruption in January 2022.
El Nino causes a warming of the sea surface temperatures, affecting the world's weather.
"The Middle East is getting hotter very fast because the desert traps the heat during global warming–warmer atmosphere is more humid and water vapour is a greenhouse gas," Murtugudde said.
"This warming is causing winds over the Arabian Sea to shift northward during summer itself and also during the monsoon. These winds are also warming the Arabian Sea very fast and bringing more humid air to Delhi, thereby raising the heat index.
"However, adding fuel to fire is Delhi's killer urban heat island effect, which amplifies the misery," said Murtugudde. The effect is caused by built-up surfaces in cities, made of concrete and asphalt, that store heat during the day and release it when the temperature cools in the evening. This heat doesn't escape to space but bounces around between buildings and inhibits nighttime cooling.
Mishra said such extreme heat has wide-ranging consequences on public health, electricity, water and the economy.
Studies have linked longer, intense heatwaves to a rise in hospitalisations, premature births and also adverse outcomes such as miscarriages in pregnant women. Research has also projected a rise in inflation and a decline in Gross Domestic Product (GDP) across the world due to climate change.
On May 29, the day Delhi's Mungeshpur station recorded the exceptional maximum temperature of 52.9 degrees Celsius, the city's power demands peaked to an all-time high of 8,302 megawatts.
Even as the India Meteorological Department (IMD) is examining the reading for possible errors, regardless, the day's maximum temperature of 46.8 degrees Celsius, recorded at the primary weather station Safdarjung Observatory, is a 79-year high. It broke the previous record of 46.7 degrees Celsius, registered on June 17, 1945.
The Delhi Fire Services, on May 29,  received information regarding over 200 incidents, of which 183 were fire-related — the highest for a single day so far this year. The National capital is also suffering from a water crisis, with people jumping queues to get water from tankers. This is Delhi's driest May in 10 years.
The hottest temperatures in the country for the day, however, registered from Haryana's Rohtak and Uttar Pradesh's Prayagraj - 48.8 degrees Celsius - an all-time high of maximum temperatures in the cities for May. The previous highest maximum temperatures ever for Rohtak and Prayagraj were 47.2 degrees Celsius and 48.4 degrees Celsius, respectively, recorded on June 6, 1995, and May 30, 1994, respectively.
Una in Himachal logged a 19-year high of 46 degrees Celsius, breaking its previous record of 45.2 degrees seen in June 2005, May 2013 and June 2019. Maximum temperatures in the State were firmly six to eight degrees above normal, with Shimla also registering its highest this season at 31.7 degrees Celsius on May 29.
The week also saw flash floods in Assam and Manipur, and landslides in Mizoram and Meghalaya triggered by Cyclone Remal. At least 6 lakh people have been affected by it.
Murtugudde explains, "Remal stayed intact on land longer because of heat from the Bay of Bengal (a consequence of El Nino) and the land still wet from pre-monsoon rain. That extracted a lot of rain from the cyclone and there are always human factors on hills." The sweltering heatwaves in the north and the floods in the North East were "not surprising since monsoon comes into the south and heatwaves exit from the north. Late-season cyclones are related to ocean warming and wind changes," he said.
Against the backdrop of sharply rising temperatures in March, with Delhi recording maximum temperatures in the mid-to-late 20s, analyses from the US-based Climate Central showed that climate change was shrinking India's spring season, with winters quickly transitioning to summer-like conditions.
In many northern regions of the country, the "spring season is disappearing," the researchers said.
They also showed that increasingly more States, including Rajasthan and Andhra Pradesh, faced the likelihood of experiencing over 40 degrees Celsius temperatures in late March, which used to be about five per cent in the 1970s and in fewer States.
Temperatures continued to rise firmly in April, with above-normal temperatures being recorded in parts of Jodhpur and Bikaner in Rajasthan at 40-42 degrees Celsius, and in Goa at 33-35 degrees Celsius.
On April 17, Mumbai's high of 39.7 degrees Celsius was the warmest ever for the month in the last 14 years. The previous high of 40.6 degrees Celsius was seen on April 2, 2009.
By April 21, heatwave to severe heatwave conditions spread to Uttar Pradesh, Chhattisgarh, Madhya Pradesh, Jharkhand, Bihar, Odisha, Gangetic West Bengal, Vidarbha, Telangana, Andhra Pradesh, Tamil Nadu and Puducherry, with maximum temperatures in the range 40-46 degrees Celsius, 4-6 notches above normal. By the end of the month, more southern regions, including Kerala, came under the heatwave's grip.
The heatwave, part of a larger one impacting billions across South and Southeast Asia, was made about 45 times more likely and 0.85 degrees Celsius hotter due to climate change, scientists from the World Weather Attribution group found.
According to the European Union's climate agency, the Copernicus Climate Change Service (C3S), it was the warmest April ever, making it the 11th consecutive month with record global average temperatures.
El Nino and human-induced climate change together have fuelled the row of record global temperatures, according to the World Meteorological Organization (WMO).
The UN's climate agency also found the current El Nino event to be among the five strongest ones on record.
Given its notorious track record, we need to be on alert for the El Nino years, according to the climate scientists.
Further, with monsoons ahead and La Niña predicted, they are expecting a cooling effect to set in, but not right away.
"I expect this dry heat to continue into June, with intermittent relief, if a weak monsoon prevails over north India during the month," said Mishra.
Murtugudde said that cooling from such a record high could happen over the coming year.
"La Niña should begin to pump the heat into the ocean and even if it's a normal year, the tropical Pacific Ocean will begin to take up heat," he said.