Heavy Rainfall Events And Heatwaves To Characterise Climate Changes In Future

Extreme weather events, including heatwaves and high intensity and very high intensity rainfall, are projected to increase.

In the upcoming years in many districts of the country, according to ‘Climate Atlas of India: District-Level Analysis of Historical and Projected Climate Change Scenarios’, a report released by the Center for Study of Science, Technology and Policy (CSTEP).

The report shows that the climate projections for the country (at district levels) during the period of 2021–2050, indicate a warmer and wetter future.

For the climate change projections, the study considered two climate scenarios or Representative Concentration Pathways (RCP) based on different levels of emissions – RCP 4.5 (moderate emissions scenario) and RCP 8.5 (high emissions scenario). The findings for the short-term period, 2030s, have been compared with the climate from 1990 to 2019, which was considered as the near past historical period, in the study.

Warmer years ahead

In 15 districts, which were analysed for heatwaves, under both RCP scenarios, the projections indicated that the number of days with temperature departure from the normal, from 4.5 degrees Celsius to 6.4 degrees Celsius and greater than 6.4 degrees will increase.

Besides, the report also says that it is projected that the summer maximum temperature in all the districts of the country under RCP 4.5 and RCP 8.5 scenarios will increase in the short-term period relative to the historical period.

The increased warming levels in the country might affect agricultural activities as well as animal and human health, the report says. The projections also show that the minimum winter temperatures will also increase by 1.5℃ to 2℃ in 18% of the districts under RCP 4.5 scenario and in 63% of the districts under RCP 8.5 scenario.

Manipur and Maharashtra

Some districts of Manipur, has been projected to have maximum warming levels under both scenarios. While a maximum warming of 2–2.5 degrees is projected under RCP 4.5 scenario, under RCP 8.5 scenario, maximum warming is expected to be 2 – 3.5 degrees.

On the other hand, some districts of Maharashtra have made it to the list of warmer temperatures during both summer and winter, increased Kharif season rainfall, increased high intensity and very high intensity rainfall events under either or both climate scenarios.

Wetter days to increase

The study says that during the historical period, the number of high intensity rainfall (51–100 mm per day) events were 4 to 615 days. According to the projections, this will increase to 15 to 760 days under RCP 4.5 scenario and to 23 to 805 days under the RCP 8.5 scenario during the years ahead.

A similar trend has also been projected for very high intensity rainfall events as they are predicted to jump from 0 to 550 days in the historical period to 0 to 600 days under RCP 4.5 scenario and 2 to 612 days under RCP 8.5 scenario. “It is important to note that of the 723 districts, only 629 (87%) districts had recorded very high-intensity rainfall events during the historical period,” the report said.

“Changes in rainfall and increase in high-intensity rainfall events will affect surface and groundwater availability with implications for water quality, availability, and management of drinking water and irrigation,” the report said.

Rise in temperature, rainfall

Between 1990 and 2019, around 70% of districts in the country saw an increase of 0.9 degrees in summer maximum temperature, the report says based on an analysis of historical data. In around 54% of the districts, the winter minimum temperature too saw an increase of 0.5 degrees. “Rainfall during the kharif or the monsoon season has increased, and the increase is particularly high in the north-east and Western Ghats districts—about 10% to 15%,” the report added.