Early pre-monsoon showers due to climate change: Study

Pre-monsoon weather activities have begun early this year due to climate change, and are likely spread across several parts of India, including some regions of north Karnataka, said a study.

The temporary respite will have ramifications, especially on agriculture, said the latest report by Climate Trends.

Rain and thunderstorms have made an appearance in the first week of March itself (between March 6 and 8) in Rajasthan, Madhya Pradesh and Maharashtra, an activity usually seen in the second half of the month, it said.

The unseasonal rains have caused crop damage.

The India Meteorological Department (IMD) has forecast light rainfall in north and central India between March 9 and 15 and above-normal rainfall with thunderstorms over major parts of the country, including the south peninsular region, between March 16 and 22.

Climate Trends said a formation of twin cyclonic circulations, fed by moisture from the Arabian Sea and the Bay of Bengal and aided by western disturbance (winds from West Asia) are likely to bring widespread weather activity over central, eastern and southern parts of India between March 13 and 18.

It said the country is gearing up for another prolonged spell of pre-monsoon rain and thunderstorms.

“While northern plains would mostly escape the hazardous activity, South Madhya Pradesh, Vidarbha and Marathwada, Telangana, Andhra Pradesh and North Karnataka will witness the fury of lightning strikes and thunderstorms,” the report added.

The early onset of pre-monsoon showers is mainly due to climate change, whose latest mark last month was February turning out to be the warmest since 1901, when the record-keeping began. The rising temperatures lead to an increase in convective activities (upward movement of hot air and moisture), thus inviting pre-monsoon showers.

“These weather activities have started a bit early. Usually, pre-monsoon activities commence during the second half of March. Also, rainfall activities during this season are confined to early morning or late afternoons, but prolonged spells are rare. This season, the abnormal temperatures have triggered multiple weather systems across several parts of the country,” said Mahesh Palawat, vice president-meteorology and climate change, Skymet Weather.

“There is already a trough running through the central parts. It will get more marked with a western disturbance which would start affecting the region by March 12. This is a clear example of what kind of climate impacts can be expected with global warming,” he added. The report said an increase in greenhouse gases in pre-monsoon season may deal with excess heat and humidity with uncomfortable conditions throughout the day and night.

Anjal Prakash, Research Director at Bharti Institute of Public Policy, Indian School of Business, and IPCC author, said it was important to note that while individual weather events cannot be directly attributed to climate change, the overall pattern of more frequent and severe extreme weather events is consistent with what scientists expect to see as the planet warms.

R H Patil, head of Agroecology Department at the University of Agricultural Sciences, Dharwad, said the findings were consistent with the phenomena.

“The convection activities due to the high surface temperature in February have definitely had an impact on the weather. We had forecast rains since February 15. But we are not sure whether they will be the usual scatter rains or the prolonged rainfall, which is not a good thing to happen this early. The heating of surface in summer till mid-May is key to the monsoon activity. If prolonged early rains lead to cooling off of the surface during those days, then it will delay the monsoon,” he added.