KEY POINTS
- Cloudbursts are sudden downpours of over 100 mm rain in an hour.
- Experts warn the Himalayas, Karakoram and Hindu Kush are highly vulnerable.
- Climate change is intensifying cloudbursts, as warmer air and oceans hold more moisture, releasing it in violent bursts.
- Pakistan, one of the most climate-vulnerable countries despite low emissions, faces more frequent extreme monsoon rains and rising annual flood disasters.
ISLAMABAD: Sudden and violent bursts of extreme rainfall, known as cloudbursts, are wreaking havoc across mountainous regions of South Asia, unleashing flash floods, mudslides and landslides that have destroyed villages and left hundreds dead.
Experts warn that climate change is fuelling these devastating events, making them more frequent and intense.
Over recent weeks, parts of Pakistan and India have been battered by cloudbursts that triggered catastrophic flooding.
In Pakistan’s Khyber Pakhtunkhwa province alone, at least 427 people have been killed since mid-August, according to local authorities.
The Buner and Swabi districts were among the hardest hit, with entire villages buried under mud and debris.
In neighbouring Indian Illegally Occupied Jammu and Kashmir, Reuters reported that at least 60 people were killed and more than 200 remain missing after torrents of water and mud swept through the Himalayan town of Chashoti.
What is a cloudburst?
Meteorologists define a cloudburst as more than 100 millimetres of rain falling in just one hour over a small area.
The India Meteorological Department uses this standard, noting that such sudden deluges are most common in the Himalayan regions of Indian Illegally Occupied Jammu and Kashmir, Ladakh, Himachal Pradesh and Uttarakhand.
“Cloudbursts are sudden, highly localised downpours that release immense volumes of water in a very short time,” explained Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology.
“The Himalayas, Karakoram, and Hindu Kush are especially vulnerable because of their steep slopes, fragile geology, and narrow valleys that funnel storm runoff into destructive torrents,” Koll said as quoted by CNN.
These events typically occur during the monsoon season, when warm, moisture-laden winds collide with cold mountain air, causing dense clouds to rapidly condense and discharge violent rain.
Why are they so destructive?
Experts say the impact of cloudbursts is magnified by a combination of poor infrastructure, weak governance and ecological damage.
“This is also a data-sparse region, whether we are studying cloudbursts or glacial outburst floods, making it harder to understand, monitor, and forecast these events,” said Koll. “The storms are also too small and fast for precise prediction.”
Islamabad-based climate expert Ali Tauqeer Sheikh highlighted additional challenges: “Because of very heavy deforestation, any torrential rain and cloudburst will result in landslides and mudslides. They’ll bring boulders and timber with them. A very high percentage of people live along water bodies, and the preparedness time is extremely limited.”
The lack of effective early warning systems, coupled with unplanned construction in vulnerable areas, often results in high casualties.
How is climate change making matters worse?
Scientists agree that the climate crisis is amplifying cloudbursts by loading the atmosphere with more moisture.
Warmer air holds more water vapour, which can then be unleashed in violent downpours when it rises over steep mountain slopes.
“Warmer oceans are loading the monsoon with extra moisture, and a warmer atmosphere holds more water, fuelling intense rainfall,” said Koll.
Sheikh added: “For each degree higher than the average temperature, there’s 7% greater moisture in the air. If there’s a stronger heatwave in the South Asian subcontinent, we can assume the rainfall will be heavier.”
Fahad Saeed, a senior climate scientist at Berlin-based Climate Analytics, told Dawn.com that in northern Pakistan, warm monsoon winds from the east are now colliding with colder air from the west, driven southward by a shifting subtropical jet stream. This interaction, he said, is creating “towers of clouds” that generate torrential rain.
Melting glaciers in the Himalayas and Karakoram are compounding the risks. While glacial melt does not directly cause cloudbursts, it destabilises landscapes, creates fragile glacial lakes and heightens the risk of catastrophic floods and landslides when extreme rain strikes, experts said.
Frontline of climate change
Pakistan contributes less than 1% of global greenhouse gas emissions, according to EU data, but is among the world’s most climate-vulnerable countries. The Global Climate Risk Index ranks it as highly exposed to extreme weather events.
The 2022 monsoon season remains etched in memory as one of the country’s worst disasters, killing nearly 2,000 people and causing $40 billion in economic losses.
Since then, deadly flooding has become an annual reality. Average rainfall seems to have decreased in Pakistan, but the frequency of torrential rains has increased.
Climate change has also altered the monsoon’s rhythm. Longer dry spells are increasingly interrupted by shorter, more intense bursts of rain — a trend scientists say has already tripled the number of heavy rainfall events across India in recent decades.
Can cloudbursts be predicted?
Forecasting cloudbursts remains extremely difficult. “It is possible to warn about the general area, but not possible to pinpoint the exact location in advance where a cloudburst will happen,” Syed Muhammad Tayyab Shah, who leads risk assessment at Pakistan’s National Disaster Management Authority, told Dawn.com.
India’s weather agency has recently installed new radars across the Himalayas to improve early warnings, but experts caution that technology alone will not save lives without stronger communication and preparedness systems.
