Explained | North India’s monsoon mayhem is a confluence of factors Premium

Rainfall this pre-monsoon was above normal due to a combination of the warm Arabian Sea and an unusually high number of western disturbances. As a result, the soils were left moister than normal, which in turn affected the evolution of the monsoon. However, the mystery is that, despite averaging rainfall over a month, a season or even multiple seasons, rainfall distribution remains uneven. Disuniform terrain and heterogeneous land-use patterns are the likely culprits.

Every year, the entire country awaits the onset and evolution of monsoon with baited breath. Each year tends to be different – and this year has managed to produce a rather unique onset and evolution thus far.

The onset this season was delayed by unforeseen interactions between typhoons and cyclones. Cyclone Biparjoy was born after the onset and lingered for longer than normal to delay the arrival of the monsoon over Mumbai by nearly two weeks. The city finally saw the monsoon  arrive together with Delhi for the first time in over half a century. The monsoon trough thus ended up with an exaggerated curvature over northwest India.

The deficit due to the delayed onset has been all but wiped out but the distribution of rainfall remains as patchy as ever, with excess rainfall over the northern Western Ghats into Northwest India and deficits extending in a horseshoe pattern from Uttar Pradesh into Odisha and back to the east into Chhattisgarh, Madhya Pradesh, and Maharashtra. Extreme heat has also been reported in parts of Himachal Pradesh, even as some areas of the state received heavy rainfall.

What is normal and what is not in this smorgasbord of heat, drought, and floods? The impact of climate change has always been of great interest, but it is worth remembering that everything today happens in a warmer world that is also more humid. As the old adage goes, climate is what we expect and weather is what we get. With global warming, a warm and humid atmosphere acts like a steroid for the weather.

Every weather event now has some contribution from global warming. One must pay close attention to the weather patterns that emerge due to other factors as well. The El Niño has been grabbing most of the headlines this year and yet it is not clear that the monsoon mayhem thus far has had much to do with the El Niño.

What is not getting noticed as much is that the wildfires thus far this year have burned over three-times the normal area and have also emitted about three times as much carbon dioxide so far. This has also had a contribution to the warming.

What else could be driving this weird summer monsoon?