Heat waves across In­dia rose over 50 years, more to come

Hindustan Times (Lucknow) - - NATION - Sne­hal Re­bello sne­hal.re­[email protected]­dus­tan­times.com

MUMBAI: Heat waves across the coun­try have in­creased in the past 50 years, by more than 31%. What’s more? In­dia must brace it­self for more next year, if the cur­rent El Nino con­di­tions per­sist in the Pa­cific Ocean.

Heat or se­vere heat waves oc­cur when ex­ces­sively hot weather, be­yond the thresh­old tem­per­a­ture of a re­gion, lasts for a pro­longed pe­riod. This could be cou­pled with high hu­mid­ity.

Ac­cord­ing t o an anal­y­sis by In­dia Me­te­o­ro­log­i­cal De­part­ment (IMD), Pune, more than half the num­ber of weather sta­tions — 57 of 103 — across the coun­try recorded heat waves in summer for an av­er­age of 550 days, be­tween 1961 and 2010.

Sim­i­larly, se­vere heat waves were ob­served for an av­er­age of 60 days, with 18 sta­tions be­ing the most af­fected over the five decades.

In­ter­est­ingly, most long spells of heat and se­vere heat waves were recorded in the years that fol­low an El Nino year — when sur­face ocean wa­ters in the eastern and cen­tral trop­i­cal Pa­cific Ocean are ab­nor­mally warmed.

“Nat­u­ral and man­made ac­tiv­i­ties, along with cli­mate change, lead to an in­crease in land sur­face air tem­per­a­ture. This means we will see a rise in ex­treme events, in­clud­ing heat and se­vere heat waves in the coun­try,” said sci­en­tist DS Pai, Na­tional Cli­mate Cen­tre, IMD Pune. Pai said states such as Ra­jasthan are al­ready wit­ness­ing a rise in heat wave con­di­tions.

In 2014, Ma­ha­rash­tra, Pun­jab, Haryana, Delhi, Ut­tar Pradesh, Ra­jasthan, Gu­jarat, Odisha and Bi­har were hit by heat waves, with tem­per­a­tures reach­ing 45 de­gree Cel­sius. With Nel­lore in Andhra Pradesh be­ing most prone, the north, north­west, cen­tral and north­east, on an av­er­age, wit­nessed more than 8-15 heat wave days.

Se­vere heat waves were ex­pe­ri­enced in the north­west, north and eastern parts for one to three days, and some­times ex­tend­ing be­yond a week.

Fol­low­ing the three El Nino years of 2002, 2004 and 2009 in the last decade, which was also the warm­est since 1880 glob­ally and since 1901 for In­dia, the num­ber of heat wave days sig­nif­i­cantly in­creased to an of av­er­age 670 days per year from 2001-2010, com­pared with 580 days per year be­tween 1991 and 2000.

In con­trast, an av­er­age of 510 heat wave days was recorded an­nu­ally dur­ing the 1961-1970 and 1971-1980 decades. There was a slight dip to 470 days per year, from 1981-1990.

Sim­i­larly, se­vere heat waves days hit­ting var­i­ous parts of the coun­try al­most dou­bled, to an av­er­age 98 days ev­ery year from 2001 to 2010 as com­pared with 48 days per year in the pre­vi­ous decade.

Fur­ther, more lives were claimed by heat waves in the years fol­low­ing El Nino (1983, 1988, 1995, 1998, 2003, 2005 and 2010).

More than 1,000 peo­ple died be­cause of a heat wave in May 2002 in Andhra Pradesh and around 200 peo­ple died across the coun­try. In May 2010, more than 250 peo­ple died in north In­dia.

“We need proper early warn­ing sys­tems, im­prove­ment in pub­lic in­for­ma­tion cam­paigns on the dan­gers of heat waves and the use of so­cial care net­works to reach vul­ner­a­ble sec­tions of the pop­u­la­tion,” Pai said.

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