Report by thinktank presents historical trends from 1990–2019 and projects future ones
Summers and winters in India have become warmer over the last three decades and are projected to become warmer as the effects of climate impact become more pronounced, a report by a Bengaluru-based thinktank has suggested. The rainfall during the Kharif season — June to October — is also expected to increase.
Climate Atlas of India: District-Level Analysis of Historical and Projected Climate Change Scenarios by Center for Study of Science, Technology and Policy (CSTEP) assessed the changes in the observed and future climate.
The thinktank looked at climate variability at the district level for 723 districts in 28 states in India, excluding Union territories.
It presented historical trends in summer (March to May) maximum and winter (December to February) minimum temperatures from 1990—2019. It also analysed Kharif (June to September) season rainfall during the period.
It also showed future trends in temperature, rainfall, and extreme events for the future (2021—2050) as changes compared to the historical period for two climate scenarios.
The scenarios were: Representative concentration pathway (RCP) 4.5 and RCP 8.5. RCP 4.5 is a moderate scenario in which emissions peak around 2040 and then decline. The other is the highest baseline emissions scenario in which emissions continue to rise throughout the twenty-first century.
The temperature in all districts showed an increase in both summer maximum and winter minimum temperatures from 1990 to 2019, the analysis found. A warming of up to 0.5 degrees Celsius was recorded in 70 per cent of the districts for the maximum summer temperature.
Severe heatwaves or days with temperature departure from the normal have also increased and expected to rise further.
Historical and projected heatwaves
Historical and projected severe heatwaves
Heatwaves (top) and severe heatwaves during the historical (1990—2019) and projected (2021–2050) periods under RCP 4.5 and RCP 8.5 scenarios. Source: CSTEP
A higher warming of 0.5℃—0.9℃ was recorded in the districts of the northern states of Punjab, Haryana, Uttarakhand, Uttar Pradesh, Bihar, Rajasthan, Gujarat and the northeastern states.
The winter minimum temperature increased by 0.5℃ in all districts, the report noted. The warming in the northern states was higher compared to the southern states.
The highest winter warming of 0.5℃—0.9℃ was recorded in 54 per cent of the districts of India, including those in the northern states of Punjab, Haryana, Uttarakhand, Uttar Pradesh, and Bihar; the western states of Rajasthan and Gujarat; and the northeastern states.
An increasing trend in rainfall during the Kharif season (June to September) was recorded during the historical period across all districts by the analysis. Overall, an increase in rainfall of up to 15 per cent was recorded during the Kharif season.
A maximum increase in rainfall by 10 per cent—15 per cent was recorded in the Northeastern districts: Arunachal Pradesh, Sikkim, and Meghalaya; the northern districts of Nagaland and the Western Ghats districts in southern India.
Read more: Understanding climate change
The report painted a grave picture of the future. A summer warming of 1℃ to 2.5℃ is projected for a majority of the districts compared to the historical period, considering both RCP 4.5 and RCP 8.5 scenarios.
For winters, warming of greater than 1℃ was projected for a majority of the districts for both scenarios.
The Kharif season rainfall is projected to increase relative to the historical period by 25 per cent–35 per cent in 2 per cent of the districts and 15 per cent—25 per cent in 18 per cent of the districts. It is expected to go up 10 per cent-15 per cent in 35 per cent of districts and less than 10 per cent for the rest.
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