Real feel in Kolkata under sun was 51°C on June 13, 2023
Photo: iStock The night of June 8, 2023 was Kolkata’s hottest June night in 50 years for which records have been maintained, according to the India Meteorological Department (IMD). The nightime temperature touched 31.2 degrees Celsius, GK Das, head of weather section in IMD Kolkata, told this reporter.
Senior officials of IMD confirmed that city temperatures, both during day and night, have been consistently on the rise over the last few years and that too over all the months.
On June 13, Kolkata’s actual temperature rose to about 39°C but the real feel under the sun was 51°C, mainly due to high clouds as well as humidity, according to Accuweather, a private weather monitoring agency.
IMD pegged the maximum temperature on June 13 to be 37.7°C but predicted that city temperature would be around 38°C on June 14.
A few bouts of showers and the arrival of monsoon in north Bengal have put a slight lease on the warming spell in Kolkata but several south Bengal districts are still experiencing heatwave conditions.
Earlier, several north Bengal regions and adjoining Sikkim suffered severe heat spells, with maximum temperature in Bagdogra in Darjeeling district reaching 40°C just before the onset of monsoon in north Bengal.
On June 14, a special bulletin released by IMD showed that seven south Bengal districts – Purbo (East) Bardhaman, Paschim (West) Bardhaman, Bankura, Paschim (West) Midnapur, Jhargram, Birbhum and Purulia — are among 26 districts out of a total of 766 in the country where heatwave conditions have been predicted for this week.
The previous record for June nighttime temperature in the city was 31°C observed on June 10, 1998 and its all-time highest nighttime temperature is 34 degree Celsius recorded on March 10, 2008.
The weather experts, however, pointed out a warming pattern that is sending a warning bell for Kolkata. “Apart from the highest nighttime June temperature ever recorded in Kolkata on June 8, the disconcerting fact is out of the top six records of maximum nighttime temperatures during the month of June in Kolkata; three happened this year, within the first 8 days of the month,” said one of the experts.
“While there has been variability in several weather parameters from year to year, it can be safely said that both day and nighttime temperatures in Kolkata have been increasing over the last few years; and the trend is consistent during all the months of the year,” said Das.
The weather expert pointed out that the daytime temperature during June had earlier soared up to 40.2°C in 2012 and 40.6°C in 2018.
Kolkata’s highest-ever temperatures have all been recorded in June — 43.9°C on June 1, 1924 and 41.2°C in April this year.
“It’s a fact that the heating pattern has shifted this year, with eastern India and adjoining Bangladesh suffering from high heat spells, mainly under the influence of western disturbances,” said KJ Ramesh, former director general, IMD.
One of the main causes of the high temperature in this region this year is the fact that a high pressure zone has not been created over Bay of Bengal, said Das. “This is affecting the moisture inflow within the city and so heat conditions have sustained.”
Kolkata and its adjoining south Bengal districts may face a far worse condition unless global and regional emissions are curtailed, said scientists referring to a recent report by the United Nations. “With high confidence we can say that extreme heat and heat-wave phenomena are going to increase in Kolkata,” said Subimal Ghosh, a scientist from the Indian Institutes of Technology, Mumbai and lead author of the UN report.
In the worst-case scenario with no significant emission cuts soon, the annual mean temperature of Kolkata may increase by 4.5°C by 2080 over the pre-industrial period, the report, prepared by Intergovernmental Panel for Climate Change (IPCC), a UN body, showed. The maximum temperature may shoot up to 49.6°C.
Several south Bengal cities are likely to face similar warming towards the end of the century under business as usual scenarios, with maximum temperatures crossing 50°C in places like Bankura, Purulia, Santiniketan and Asansol, according to the IPCC report.
“A major part of the temperature rise has been happening from the mid-1990s. The period since then has seen major environmental destruction, be it filling up of waterbodies, cutting down trees and wholesale concretisation. That is impacting the city’s weather,” said an environmental expert.
The report also predicted that the city may experience a temperature of 35°C or more for 150 days a year within a few decades from now.
“We have analysed the IPCC report and found that about 80 per cent rise in the city’s temperature is slated to have happened after 2014,” said Aniruddha Mukherjee, head of the environmental science department of Calcutta University.
The report showed that urbanisation has contributed to a rise in the city’s temperature, saying “urban centres and cities were warmer than the surrounding rural areas because of the urban heat island effect”.
Urban heat island effect arises from several factors, including reduced circulation of air and heat being trapped because of multi-storeyed buildings standing close to one another, heat generated from human actions, presence of too many concrete structures and reduced green cover.
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