In a concerning trend, Kolkata temperature in April has risen by six degrees Celsius over the five years from 2019 to 2024. This year, the city experienced a maximum Kolkata temperature of 40 degrees Celsius for nine consecutive days, according to a report by the environmental group SwitchON Foundation.
The report, titled ‘Heatwave Havoc in April, a Month of Record-Breaking Temperature,’ draws on data from various sources, including the India Meteorological Department (IMD). It highlights the significant rise in both maximum and minimum Kolkata temperatures over the past five years. Specifically, the minimum Kolkata temperature in April has increased by five degrees Celsius during the same period.
In 2019, Kolkata temperature fluctuations were more frequent compared to 2024, with higher temperatures observed towards the end of April in both years. This year, Kolkata recorded its highest temperature in the past five decades on April 30, reaching a scorching 43 degrees Celsius. This figure is 7.4 degrees higher than the normal Kolkata temperature for that time of year, signaling severe heatwave conditions in the city.
The report also notes that the lowest minimum Kolkata temperature of 24.7 degrees Celsius on April 12 was 0.9 degrees above the normal temperature. Additionally, Alipur, a part of Kolkata, saw the temperature exceed 40 degrees Celsius for nine days in April this year.
Comparing April 2024 to April 2019, the report reveals that Kolkata experienced higher maximum temperatures on 90 percent of the days and higher minimum temperatures on 93 percent of the days in April 2024. These findings underscore a consistent increase in Kolkata temperature, contributing to more extreme heatwave conditions.
Several factors have contributed to the rising Kolkata temperature. The report indicates a current lack of weather systems, such as cyclonic circulations or trough lines, which typically trigger rainfall in Kolkata. Usually, moist air from the Bay of Bengal brings rain, but this year, the air has been unusually dry due to prevailing dry winds.
Further compounding the issue, studies conducted by universities in West Bengal show that Kolkata’s annual mean land surface temperature has increased by 4.7 degrees Celsius over the last 30 years. This increase in Kolkata temperature is primarily attributed to a significant loss of vegetation and a rise in built-up areas, leading to the urban heat island effect.
This year, April saw minimal rainfall in Kolkata, with only 0.5 mm recorded on April 7. In stark contrast, April 2023 experienced four rainy days, accumulating 50 mm of rainfall, with three of these rainy days occurring towards the end of the month.
Vinay Jaju, Managing Director of SwitchON Foundation, emphasized the urgency of addressing these extreme Kolkata temperature increases. He stated, “In the face of unprecedented heatwaves, it is crucial that we recognize the urgency of climate action and its profound impact on vulnerable communities. Let us unite to implement sustainable solutions that prioritize the well-being of all, ensuring a resilient future for generations to come.”
On Monday, Kolkata recorded a maximum temperature of 34.2 degrees Celsius, with maximum humidity at 90 percent. The IMD has forecast thunderstorms and light to moderate rainfall in the southern districts of West Bengal starting Tuesday. All districts are expected to experience light to moderate rainfall from Tuesday onwards, which could provide some relief from the high Kolkata temperatures.
The rising Kolkata temperatures not only reflect broader climate change trends but also highlight the immediate need for adaptive measures to mitigate the impacts on the city’s residents. The persistent increase in Kolkata temperature, coupled with decreased rainfall, exacerbates the heatwave conditions, making it imperative for both government and community action to address these challenges effectively.