Changes in Monsoon pattern and impact of climate change

Contact Counsellor

Last Updated13/10/2022

Recent incessant rain over Delhi & North -Northwest India evidence shifting patterns in monsoon activity over the Indian subcontinent.
Monsoon - earlier confined to the four-month June-September period, is clearly spilling over into October now.

3 years ago, the India Meteorological Department (IMD) revised the expected dates of onset and withdrawal of monsoon for several regions of the country.
The withdrawal dates for North, Northwest and Central India were pushed back by 1-2 weeks to account for the trends witnessed over the last 50 years.

There has been seen a clear prolongation of the monsoon season.
The nature of rainfall is very different — it is not a short-duration heavy downpour, but sustained rain over a few days.
The recent rainfall over Western UP, Uttarakhand, Haryana, Eastern Rajasthan & Delhi were a result of the interaction of monsoon winds, moving east to west, with the western disturbance wind system.
Happen several times during the monsoon season.

The extension of the monsoon season could also be seen as a consequence of global warming.
A reason for the spillover of monsoon rainfall to October could be that the oceans (Bay of Bengal and Arabian Sea) are now warmer.
Warmer ocean currents help the formation of monsoon winds.
Earlier, rainfall during the monsoon season would bring down the temperature of the ocean.
But possibly because of global warming, the oceans continue to remain warm even after the traditional monsoon season is over.
Oceans could thus be playing a role in keeping the monsoon alive beyond the traditional period.
A warmer atmosphere has a greater capacity to hold water.
When this water is finally released, it often results in a heavier downpour than would be expected otherwise.
Accounts for the increasing instances of extreme rainfall events.

The changing patterns are creating forecasting complications for the IMD.
IMD has invested heavily in setting up observational equipment, upgrading computing resources, and fine-tuning weather forecast models.
Its forecasts are more accurate and specific, & impact-based and actionable.

Indian agriculture depends on monsoon rainfall for irrigation.
Drinking water supply and generation of electricity are also linked to the monsoon.
Implications for dam management
Most reservoirs in the northern and central parts seek to attain full capacity levels by Sept end as not much rain is expected after that.
But if the monsoon consistently spills over into October, this practice would need to be revised as well.