Scientist says sudden, heavy rain in Bengaluru due to global warming

BENGALURU: Large swathes of land, mostly in the IT hub in Bengaluru, have been inundated following unprecedented torrential rains since September 4.

Unlike in the past, it is being observed that the pattern of rainfall has changed — from an occasional drizzle and shower to a sudden and heavy downpour now.

There are increasing instances of heavy and incessant rainfall leading to overflowing of lakes, flooding and water logging, which have stumped weathermen and town planners.

While there is a lack of detailed research corroborating link between climate change and monsoon, meteorologist and Professor at the Centre for Atmospheric and Oceanic Sciences and the Chair of Divecha Centre for Climate Change, IIISc, S K Satheesh said that extreme weather events like heavy rainfall over a short period could be because of a “gradual increase in the number of cloud condensation nuclei (aerosols) in the atmosphere and global warming.”

Atmospheric aerosols are known to play a crucial role in cloud formation processes by acting as cloud condensation nuclei (CCN). They define the droplet size distribution forming rain pattern.

ALSO READ | #LeaveBengaluru trends amid man-made tragedy

For a given amount of water vapour content in the atmosphere, a lesser number of large cloud droplets will form if the number of aerosols is less.

For the same amount of water vapour content, a large number of smaller cloud droplets will form when the number of aerosols is high, which in polluted conditions can lead to heavy rainfall within a short period of time.

Speaking to TNIE, the scientist said that the “aerosol loading in India is increasing in the last 10 years because of anthropogenic activities. There is a two per cent per annum increase in the loading of the aerosols in the atmosphere in the Indian subcontinent. This could be because of anthropocentric activities coupled with unsustainable landscape planning and urbanisation etc,” said the meteorologist.

Satheesh cautioned, “Increase in the number of aerosols in the atmosphere will not only alter the rainfall pattern, it will also adversely impact public health, leading to an increased number of people falling sick with respiratory disorders, block solar radiation hitting the earth thereby impacting climate and agriculture, by default,” added Satheesh.

ALSO READ | Minister Munirathna's 'unwelcome to Bengaluru' remark sparks row

“Presence of a large number of aerosols in the atmosphere will also impact satellite remote sensing of the earth’s surface,” he added.

Satheesh said that though there are enough policies for pollution control and regulation of construction activities, enforcement is a problem.

“Research should provide a scientific basis for governments at all levels to develop climate-related policies. Linking disaster management with artificial intelligence (AI) is another aspect, which needs attention with a changing climate,” said the noted scientist.