As the planet gets warmer, expect intense, extreme rain

NO NET GAIN Short bursts of extreme precipitation do not reduce water stress or help recharge the water table. Instead, they often lead to flash floods

Intense bursts of rain and continuous downpours have increased across towns and cities over the past few decades, with Bangalore receiving 35% of its annual average rainfall this year even before the onset of the monsoon. Last year, Ahmedabad (180mm in 24 hours) and in 2005, Mumbai Metropolitan Region got flooded when it didn’t stop pouring (994 mm in a 24 hours).

“The number of days with heavy rainfall is increasing and the number of days with light rainfall is decreasing,” M Mohapatra, senior official at the India Meteorological Department (IMD), said. “The same amount of rainfall is happening over a fewer days.”

The monsoon season is a dangerous and unsettling time in India, with most deaths reported from heavy rains and flooding in the four months of rain from June to September.

“Increasing trends in daily extreme precipitation in India have been observed during the recent decades,” said a recent study published in Geophysical Research Letters in June this year.

“Moreover, urban areas in India have witnessed eccentric precipitation extremes in the past, which have affected human lives and infrastructure.”

Between 1950 and 2017, India has reported 285 floods that have impacted 850 million people, left 19 million homeless and killed about 71,000. In the past decade. Flood damage has led to losses of ₹ 206 billion every year, according to the International Disaster Database.

But the short bursts of extreme precipitation worry scientists .

Such events may boost the total amount of rainfall but they do not necessarily reduce water stress or significantly recharge the water table.

On the contrary, much of the rain discharge is difficult to manage and often causes flash floods, which are detrimental to infrastructure.

Incidences of extreme rainfall, that precipitate flooding, are projected to increase as the planet warms. India is not just prone to weather-related disasters. Its high population density and poor infrastructure also put more people at higher risk.

In the last two years alone, 25 million people have suffered impacts from heavy rains and floods and at least 2,000 people have died in these episodes.

In India, both large-scale floods from continuous heavy downpours and flash floods from sudden bursts of rain are expected to strike more often.

“A warming climate will cause more intense and more frequent extreme rain events,” Vimal Mishra, a climate scientist at IIT Gandhinagar and co-author of the paper, said. The increase in rainfall extremes is being driven by anthropogenic warming, Mishra and his colleagues said in a 2018 paper, noting that in the worst case scenario of unchecked greenhouse gas emissions, such events will increase significantly over south and central India by 2050.

“For cities, daily rainfall data is not that helpful, even 5-10 minutes of heavy