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Temperatures around 40 degrees celsius in the last week of September are not usual in Assam. Yet, with an adversely changing climate, people in the northeastern state are reporting health complications arising out of the ‘heat dome effect’ for the past few days.
The heat dome effect is explained as a type of high-pressure system (also known as anti-cyclone) that forms over a large area in the atmosphere, and causes extremely hot and dry weather conditions.
So far, seven people in Assam have lost their lives due to the ongoing 40-degrees heat which the mobile phone applications flag as ‘feels like 50 degrees’.
What has exacerbated the crisis for the residents of Assam is that the unusually high temperatures aren’t cooling down at night.
The weakening monsoon circulation, poor soil moisture, heavy exposure to sunlight, local factors like heavy deforestation and expanding industrial activity have all contributed towards the heat dome effect now prevalent over a week in Assam, according to experts.
“Usually, air circulation over the northeastern region keeps the region cool. This circulation emerging from the Bay of Bengal hits the region with low velocity winds that provide the much-needed moisture, causing short spells of showers throughout the month of September,” Rahul Mahanta, an associate professor specialising in climate science at Guwahati-based Cotton University, told Down To Earth (DTE).
“This year, we noticed that the circulation is completely absent and in its place, a high-pressure system prevails over Assam and adjoining states. Another crucial factor in the region has been soil moisture which generally has a cooling effect during the night. However, this year, we have witnessed an absence of soil moisture as well which has led to the high night-time temperatures. Based on these observations on the air circulation above the region, one can see the presence of a heat-dome effect,” Mahanta elaborated.
The absence of the monsoonal circulation, according to Mahanta, can be attributed to the imminent weakening of the Gulf Stream. Also, changes in the jet stream that is controlled by atmospheric circulation is responsible.
“The monsoonal circulation is impacted by the changes currently happening to air currents, which are largely threatened by climate change,” added Mahanta.
Besides these, the professor explained that external local factors like deforestation across the region, rapid industrialisation in the region and urban heat islands have significantly contributed to the heat. In two decades starting from the year 2000, Assam has lost over 2,690 square kilometres of forests to various anthropogenic activities.
The Regional Office of the India Meteorological Department (IMD) in Guwahati had issued warnings and advisories last week about the prevalent heat conditions.
According to MET statistics, all the major cities of Assam, including Guwahati, Silchar, Dibrugarh, Jorhat, Tezpur, Dhubri and North Lakhimpur broke previous records of highest temperatures ever recorded in the month of September.
“This heatwave may be happening due to the weakening monsoonal circulation. This week however we will see short spells of rain across the region,” Sanjay O’Neill Shaw, a senior official at IMD-Guwahati told DTE.
As is the case with the vagaries of the weather, the underprivileged sections of the society have faced the worst brunt of the ongoing heatwave in Assam.
On September 23, Badal Bhuyan, a 35-year-old daily wage labourer collapsed as soon as he reached his house in Bandarmari Bhuyan Line of Demow in Upper Assam.
Bhuyan was referred to the Dibrugarh Medical College where he succumbed to a heat stroke that evening.
Similarly, in Jorhat town, two unidentified workers aged about 40 and 55 respectively succumbed to a heat stroke. The police authorities in Jorhat are yet to ascertain their identities.
On September 24, Anup Koch (44), a contractual worker in Tezpur's Indian Air Force station collapsed after reaching home and breathed his last in a government hospital in Tezpur leaving behind his wife and two children.
Dibakar Kuli, a 27-year-old farm worker, similarly suffered a heat stroke in Malaya Chapori of Majuli. Vernacular journalists told DTE that the government ambulance arrived late which led to his death.
On the other hand, Jibakanta Pegu (30) collapsed in a Dergaon bus stand due to a stroke. Pegu did not make it to the Jorhat Civil Hospital where he was referred.
Furthermore, 20 women tea garden workers also collapsed in a tea estate in Dibrugarh’s Moran. Due to the quick response of the local worker unions and the tea estate management, these women recovered after receiving primary treatment.
Taking cognisance of the prevalent heat conditions, Assam State Disaster Management Agency (ASDMA) has circulated a format to the district health officials.
“The health department records deaths or any kind of health situation due to heat. We do not record the deaths in case of an extreme heat situation. However, with the prevalent situation, we have circulated a format to take note of any casualty due to heat among the health department officials,” Mandira Buragohain, Project Officer, Knowledge and Climate Change of ASDMA told DTE.
While IMD has issued fresh warnings of increased rainfall activity in the next few days, ASDMA officials said that they did not declare a heat wave because of the standards followed by National Disaster Management Authority (NDMA).
“Although the prevailing temperatures broke all records, the protocol of declaring heat waves depends on extreme heat conditions which are experienced in North or Central India like the summer loo or very high temperatures. We have been observing the temperatures and the decision not to declare a heat wave was based on that,” Buragohain explained.