The researchers noticed a consistent warming phase in northwestern and southwestern India and a progressive cooling pattern in the northwest and southwest regions of the country.
There is a spatial shift in heatwaves in India making these prolonged episodes of extreme temperature events occur in new regions that it was earlier, finds a recent analysis by Benaras Hindu University’s Mahatma Centre of Excellence and Climate Change research (MCECCR) in collaboration with the Department of Science and Technology and Ministry of Earth Sciences.
The MCECCR study came to the conclusion on analyzing temperature data of pre-monsoon (March-May) and early summer monsoon (June-July) seasons from the India Meteorological Department of a period of 65 years for assessing monthly, decadal and seasonal trends in the country. The researchers noticed a consistent warming phase in northwestern and southwestern India and a progressive cooling pattern in the northwest and southwest regions of the country.
What the temperature data reveals
There is a “Spatio-temporal shift” in the occurrence of heatwave events across India. Moreover, the trend of heatwaves has increased in three regions that were already prone to extreme weather conditions i.e northwestern, south0central and central India. Madhya Pradesh recorded the highest events of heatwaves.
Heatwaves are traditionally associated it Delhi, U.P and Bihar, and northern Madhya Pradesh and there are new locations now where these events are taking place, especially in the last two decades, finds BHU’s Rajesh Mall, also the lead author of the study along with Nidhi Singh and Saumya Singh. The study that analyses daily temperature over the past seven decades on a 0.25 square kilometer grid found that heatwaves now occur in south Madhya Pradesh, Andhra Pradesh, Tamil Nadu, and Karnataka as well. According to researchers, heatwaves in the southern part of India like Karnataka and Tamil Nadu is especially significant indicating the increase in such conditions in the future.
Interestingly, though heatwaves have comparatively decreased in the Gangetic planes of West Bengal and other Eastern regions (0.13 events/year). Moreover, heatwaves have emerged in southern states which had previously not experienced such events. The spatial surge of heatwaves during 2010-16 and 2010 and southward expansion are the outcomes of the study.
The highest number of heatwave days were experienced over, northern, northwestern, eastern coastal, and central regions n the summer months between 1961 and 2010. There is an average of 1-3 severe heatwave days and eight heatwave days occurring during the season
Talking about the heatwave conditions and factors that exacerbated it increases in nighttime temperatures that disallow heat discharge at night and increasing humidity levels.
Moreover increasing trend of heatwave days and severe heatwave days were observed in the decade of 2001 and 2010 and its previous decade. The shift of heatwaves can further impact eastern and western coasts that are so far unaffected by this weather condition.
Heatwave-related deaths saw an increase from 5,330 deaths in 1978-1999 to extreme cases of 3,054 in 2003 and 2,248 deaths in 2015.