Mumbai billboard collapse: Why cities need to gear up for ‘multi-hazard weather events’

Here is a look at such events and their impact.

But first, what happened in Mumbai?

On May 13, Mumbai experienced a pre-monsoon thunderstorm between 3 pm and 4 pm. The event began with a dust storm and was followed by rain that took place in the city and suburban areas. The wind speeds ranged from 40 kmph to 90 kmph, varying from place to place. The India Meteorological Department’s (IMD) Santacruz and Colaba weather stations recorded a top wind speed of 87 kmph and 51 kmph, respectively.

The winds damaged railway infrastructure, banners, hoardings, and trees at different locations. They also led to the collapse of a massive 120×120 feet billboard in Ghatkopar (east), resulting in the deaths and injuries of numerous people.

How do thunderstorms develop and are they becoming more intense?

Thunderstorms and dust storms are natural weather phenomena and occur during peak summer and pre-monsoon periods. Persistent surface heating and favourable wind conditions combine to form thunderstorms.

“Thunderstorms are mesoscale (at a smaller scale), localised events which can cause a lot of damage due to the strong winds that accompany them. Dust storms can also cause damage. Thunderstorms form during later afternoons and evenings, form quickly and die down soon,” said M Rajeevan Nair, former secretary, Ministry of Earth Sciences.

With rising global temperatures, countries, including India, are witnessing more intense and frequent thunderstorms as at warmer temperatures, the atmosphere can hold more water vapour, according to Nair.

Sunil Kamble, director, regional meteorological centre, India Meteorological Department (IMD), Mumbai said that IMD issues impact-based forecasts for weather events like thunderstorms and heavy rain spells. “We issue advance forecasts and nowcasts too. We also share the forecasts with the city’s disaster department, airport and railways so that action can be taken at the ground-level,” said Kamble.

What are climate and weather-related hazards?

Meteorological events that can cause extensive damage to human life, properties, and animals are broadly categorised as climate or weather-related hazards. In 2022, the IMD prepared an atlas of 13 such hazards – dust storms, thunderstorms, hailstorms, cyclones, drought, extreme rainfall events, floods, fog, lightning, snowfall, heatwave, coldwave, and strong winds. This atlas mapped the vulnerability of districts to these climate hazards based on disaster data, climatological archives, population, and housing density.

These events can also be categorised as multi-hazard events as they can cause fatalities, displacement, property damage, livestock deaths, crop damage as well as widespread damage to infrastructure.

Lubaina Rangwala, Program Head, Urban Development, World Resources Institute said the Mumbai episode highlights the need for climate-proofing infrastructure in big cities.

Rangwala said a lot of focus in Mumbai is on urban flooding. But being a coastal city, it will keep facing different kinds of risks, including multi-hazard events. “We need climate-proofing of infrastructure to withstand multi-hazard events. The billboard accident showed that it was not able to withstand high wind speeds. You cannot have objects that can potentially fall or projectile onto people in such a congested city. Authorities need to review this kind of infrastructure”.

What is the impact of such events on human life?

The National Crime Records Bureau (NCRB) 2022 report on accidental deaths and suicides in India revealed that in 2021, there were 8,060 accidental deaths in India due to ‘forces of nature’ such as lightning, heat stroke, exposure to cold, floods, landslides and torrential rains.

Lightning led to the most number of deaths, accounting for 35.8% of more than 8,000 deaths by natural events. In terms of absolute numbers, lightning strikes killed 2,887 people, floods killed 547 people, landslides killed 269 people, exposure to cold killed 720 people and heat stroke killed 730 people.