Meteorologists have said that an average rise of 1 degree Celsius in summer temperatures — as predicted by the India Meteorological Department (IMD) on Thursday — over most of India would mean more days of extreme heat as well as a higher likelihood of heat waves compared to last year.
“We don’t have a count of the number of heat wave days across the country last year but this year [the number] is likely to be greater,” said G.P. Sharma, chief meteorologist, Skymet, a private weather forecasting agency.
The Indian Meteorology Department (IMD) defines a heatwave as an excess of five to six degrees C over the maximum daily temperature (over a 30-year period) of less than 40 degree C or an excess of four to five deg. C over a normal historical maximum temperature of over 40 degree C. The IMD declares a heat wave when the actual maximum temperature is above 45 degree C.
More heatwaves could mean a greater public health concern. Last year, heat waves killed over 1,500 in Andhra Pradesh alone. As >The Hindu reported in February , this year the IMD will be issuing a summer fortnightly forecast about the likelihood of heatwaves across the country.
On Thursday the Met Department stated that the summer months of 2016 would be warmer than normal across all meteorological sub-divisions of the country and above-normal, heat wave (HW) conditions are very likely over central and northwest India during the period.
Much warmer January India experienced significantly above normal temperatures during January and February of this year with monthly anomalies of 1.5 deg. C and 2 deg. C, when compared to the thirty-year average of 1961-90. Moreover, 2015 was the third warmest year ever recorded since 1901. All the temperatures (maximum, minimum and mean) of most of the sub-divisions from northwest India, Kerala from south India and Vidharbha from Central India are likely to be above 1 deg. C, the department said in a press statement .
The IMD concurs that the frequency and duration of heat waves over the country are increasing and attributes it to increasing greenhouse gases due to anthropogenic activity and the El Nino — characterised by the warming of sea surface temperatures over the Pacific Ocean and correlated with droughts in India — that is also linked to more heat waves.
“Generally, El Nino years are followed by warmer temperatures,” said D.S. Pai, chief meteorologist, IMD, “but were a La Nina (an anti-El Nino) to form then that could reduce temperatures as well.”
