North East states including Meghalaya may experience overall warming of summer and winter minimum temperatures, increase in the number of rainy days, and increase in the number of heavy rainfall events in the next 30 years from now.
These are the findings of “District-Level Changes in Climate: Historical Climate and Climate Change Projections for the North-Eastern States of India” by the Centre for Study of Science, Technology and Policy (CSTEP), a Bengaluru-based think tank.
The study projects changes in temperature and rainfall patterns in Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura over the next three decades (from 2021 till 2050) and compares it to the historical period (from 1990 to 2019).
It analysed two representative scenarios: first at moderate emissions, what in technical terms is called as Representative Concentration Pathways (RCPs).
According to the study, temperature and rainfall in Meghalaya are projected for the 2030s under two RCPs – RCP 4.5 (medium emission) and RCP 8.5 (high emission) scenarios.
The projected changes in the summer maximum and winter minimum temperatures for all the districts of Meghalaya as per RCP 4.5, the summer maximum temperature will increase by 1°C to 1.5°C while in winter the minimum temperature will increase by 1°C to 2°C.
In RCP 8.5, the summer maximum temperature is projected to increase by 1°C to 2°C and in winter the minimum temperature will increase by 1°C to 2°C.
The analysis of rainy days under historical and projected periods shows that there will be an increase in the number of rainy days during the projected period in all the districts of Meghalaya. According to the India Meteorological Department, a rainy day is defined as a day with rainfall of 2.5 mm or more.
RCP 4.5 scenario projected rainfall to increase by one to five days annually in all the districts. The increase is by five days in South West Khasi Hills; four days in East Garo Hills, North Garo Hills, Ri Bhoi, South Garo Hills, and West Jaintia Hills; three days in East Khasi Hills, South West Garo Hills, and West Garo Hills; two days in West Khasi Hills; and one day in East Jaintia Hills.
RCP 8.5 scenario projected rainfall to increase by one to twelve days annually in all the districts. The increase is by twelve days in Ri Bhoi; ten days in West Jaintia Hills and South Garo Hills; eight days in East Garo Hills and South West Garo Hills; seven days in East Jaintia Hills, North Garo Hills, West Garo Hills, and West Khasi Hills; and six days in East Khasi Hills and South West Garo Hills.
The total number of high-intensity rainfall events increases from 97 to 416 days during the historical period (1990–2019) to 124 to 450 days in the 2030s (2021–2050) under the RCP 4.5 scenario and 167 to 476 days under the RCP 8.5 scenario.
RCP 4.5 scenario projected high-intensity rainfall events are projected to increase per annum by one to four events. The increase is by four events in West Jaintia Hills; three events in East Khasi Hills and South West Garo Hills; two events in Ri Bhoi, South Garo Hills, West Garo Hills, and West Khasi Hills; and one event in East Garo Hills, East Jaintia Hills, and North Garo Hills. No change is projected in South West Khasi Hills.
RCP 8.5 scenario projected high-intensity rainfall events are projected to increase per annum by one to five events. The increase is by five events in and West Jaintia Hills; four events in East Khasi Hills; three events in North Garo Hills, Ri Bhoi, South Garo Hills, South West Garo Hills, West Garo Hills, and West Khasi Hills; two events in East Garo Hills and East Jaintia Hills; and one event in South West Khasi Hills.
The total number of very high-intensity rainfall events increases from 12 to 475 days during the historical period (1990–2019) to 78 to 495 days in the 2030s (2021–2050) under the RCP 4.5 scenario and 92 to 480 days under the RCP 8.5 scenario.
RCP 4.5 scenario projected very high-intensity rainfall events to increase per annum by one to four events. The increase is by four events in West Khasi Hills; two events in East Khasi Hills, East Jaintia Hills, North Garo Hills, West Garo Hills, and West Jaintia Hills; and one event in East Garo Hills, Ri Bhoi, South Garo Hills, South West Garo Hills, and South West Khasi Hills.
RCP 8.5 scenario projected very high-intensity rainfall events to increase per annum by one to five events. The increase is by five events in West Khasi hills; two events in East Garo Hills, East Khasi Hills, North Garo Hills, Ri Bhoi, South West Garo Hills, and West Jaintia Hills; three events in East Jaintia Hills and West Garo Hills; and one event in South Garo Hills and South West Garo Hills.
The temperature is projected to increase in the short term (2021–2050) in all the districts under RCP 4.5 and RCP 8.5 scenarios compared to the historical period (1990–2019). The summer maximum temperature is projected to warm by 1°C to 1.5°C under the RCP 4.5 scenario and 1.5°C to 2°C under the RCP 8.5 scenario. The winter minimum temperature is projected to warm by 1°C to 2 °C under RCP 4.5 and RCP 8.5 scenarios.
The study recommended that since the district-level climate change assessment for the north-eastern states provides an understanding of the historical climate and climate projections for the 2030s, all North East states need to integrate this information into the State Action Plans on Climate Change, which are currently under revision.
“Additionally, states need to formulate plans and strategies based on climate risk assessments, which account for climate hazards, vulnerability, and exposure. Instituting studies to map climate risks will contribute to climate preparedness and help the states buffer the loss and damage likely to be incurred from extreme climate events,” the study said.
