Drier June, wet Sept? Data hints at monsoon shift
NEW DELHI: India’s summer monsoon is undergoing significant changes, influencing not just agriculture – for which the rains are a lifeblood --- but also the length and intensity of the summer.
Recent data from the India Meteorological Department (IMD) shows a trend of weaker monsoon rainfall in June, followed by prolonged, heavy rainfall in September. This shift is accompanied by rising temperatures during monsoon months and an increase in the number of dry days over eastern India. Scientists say India should prepare for the monsoon’s new character, which is changing when rain falls, where it falls, and with what intensity.
Since 2008, nine years saw below normal monsoon rainfall in June and six recorded near normal to above normal rainfall, as per data with IMD. Here, normal is the average rain received during 1971-2020 in June.
Increasingly, June rainfall appears to be either weak or patchy, which means the monsoon properly begins only in July, especially over east, central and northwest India.
At the same time, IMD’s monthly climate summaries also show another interesting trend: Since 2008, in September, when the monsoon is normally expected to wind down, nine years have recorded above normal rain as compared to six with near normal or below normal rain. For July, seven years saw below-normal rain and eight above-normal. In August, eight years recorded below-normal rain and seven above- and near-normal.
M Rajeevan, former secretary of the ministry of earth sciences, said, “We are seeing that there is a tendency of monsoon coming late in June or being weaker in June and then continues well after September. The delay is pronounced over central and east India.”
Rajeevan added this shift might be linked to delayed western disturbances and Arctic sea ice melting as a result of the climate crisis, though the exact causes remain unclear.