Summer here, intense heat in store
NEW DELHI: Summer seems to arrived early across India with maximum temperatures already hovering around 2-5 degrees Celsius above normal in many parts of the country on February 28 — the day the IMD picked to predict an intense summer across India, implying a greater threat to human and crop health.
The early onset of summer also means a higher probability of heat waves developing earlier than expected, IMD said. On Wednesday, the agency issued a heat wave warning for Mumbai, Raigad and Ratnagiri for Wednesday and Thursday.
Heat waves don’t just impact human health; they also affect crops, deplete water resources and put pressure on the power system because of the spike in demand for cooling. The aboveaverage temperatures could affect winter crops, including staple wheat, in the absence of precautionary measures, experts warned. “Wheat is susceptible to a condition called terminal heat if, during maturing and harvesting stage, temperatures rise abnormally,” said Dr R Nagesh, a retired scientist from the Indian Agricultural Research Institute.
“There is a danger of productivity losses.”
A sustained heat wave is bad news for farmers across the country who are already battling an agricultural crisis.
The National Disaster Management Authority describes a heat wave as a period of abnormally high temperature. IMF’s own criteria says a heat wave need not be considered till the maximum temperature reaches 40 degrees Celsius or, if it is lower than that, when the maximum temperature is 5-6 degrees Celsius more than the normal temperature. On Wednesday, Mumbai recorded a maximum temperature of 37.4 degrees Celsius, 5.5 degrees above normal.
This was the third successive day of heat-wave conditions in the city (the maximum temperature was higher at 37.8 degrees on February 27), which perhaps explains IMD’s move. Other parts of Maharashtra were hotter. The highest temperature in the state was recorded at Bhira (41 degrees Celsius, 5 degrees above normal).
Heat waves normally occur between March and June, although some have been recorded even later.
In Delhi, heat wave conditions normally develop in the beginning of May, when maximum temperatures breach the 40 degrees Celsius threshold. That looks likely to happen earlier this year with the northern plains already heating up. “The maximum temperature in the northern region has already touched 36.2 degrees C on February 27,” Kuldeep Srivastava, a senior IMD scientist said. “The maximum and minimum temperatures in February were about 3 degrees C above normal.”
“It is likely that heat wave conditions will hit the region earlier than expected,” he added.
The core heat wave zone spreads over Punjab, Himachal Pradesh, Uttarakhand, Delhi, Haryana, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana and the meteorological subdivisions of Marathwada, Vidarbha, and Madhya Maharashtra in Maharashtra and coastal Andhra Pradesh in Andhra.
This summer too will be hotter, IMD said, with mean temperatures between March and May being 1 degree Celsius above normal.
A draft IMD report noted that 2017 was India’s 4th hottest year, and the 4th consecutive recordbreaking year, mostly because of record-breaking temperatures in the January- February period, classified as winter.
Officials in Mumbai cited unique conditions for heat wave conditions forming in the region. “The heat wave conditions are for isolated parts of the Konkan coast, including Mumbai, due to a lower-level anti-cyclonic circulation over Gujarat and parts of Maharashtra, which is pulling warm easterly to north-easterly winds over Mumbai and surrounding areas. The easterly winds are also not allowing the sea breeze (cool westerly winds) to settle over the city fast enough,” said KS Hosalikar, deputy director general, western region, IMD.
There is an increase in the frequency and duration of heat waves according to IMD officials. The rise in average temperatures that is fuelling the heat waves is attributed to increasing greenhouse gas emissions and warming of sea surface temperatures.
The National Disaster Management Authority reported recently that heat wave deaths have dropped significantly in recent years partly because of early warnings.
However, experts say the cost of heat waves go beyond fatalities and include health care costs and the loss of productivity.
“When people are exposed to very high temperatures, they start developing a temperature and the body’s heat-regulation mechanism and circulation fails; people can die if they are not cooled down immediately,” said Dr Dileep Mavalankar, director of Indian Institute of Public Health, Gandhinagar-Public Health Foundation of India.
It isn’t just Mumbai and the North, Hyderabad has seen an increase of 3-4 degrees C from normal in the minimum temperature during January and the first week of February.
“We entered summer in the second week of February and the maximum temperatures are gradually rising. It is quite common to have a deviation of 1.5 to 2 degrees Celsius during this period, but the deviation will go up to four to five degrees in the peak summer season in May,” an official in the IMD control room in Hyderabad said, asking not to be identified.
Responding to the IMD forecast, West Bengal chief minister Mamata Banerjee held an emergency meeting with the ministers and officials of the agriculture and irrigation department.