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On June 2, 2019 a cloudburst over Uttarakhand’s Lambagad village in Chamoli district killed one person. Soon after, an alert was issued in the state’s Almora region owing to rising water level in Ramganga River.
While this is the first cloudburst of 2019, the state faced around a dozen of these extreme weather events last year. Experts say not only has the frequency of such events increased, but their timing has also changed.
“The number of cloudbursts is definitely increasing and their time pattern has also changed. We are hardly in June right now and a cloud burst has happened. Earlier, cloudbursts were common during monsoon or post-monsoon period, which is September-October. Cloud bursts are happening sooner every year,” said Kireet Kumar, scientist at GB Pant National Institute of Himalayan Environment and Sustainable Development.
Kumar added that the main reason for this increase is rising temperatures due to climate change. “Rainfall depends on temperature which impacts wind pattern and cloud formation. With increasing temperatures, such events are on the rise,” he said.
The decadal temperature rise in the Himalayan region is higher than the global rate of rising temperatures. “Several climate change studies over the Himalayas reported a consistent warming in the present climate with rate of warming much higher than the global average of 0.4 degree Celsius. The reported rate of warming over Nepal is 0.6 °C/decade during 1977–2002 and 0.6 °C/100 year during 1901–2002 over the eastern Himalaya," according to a study titled Future changes over the Himalayas: Maximum and minimum temperature published in the journal Elsevier in January 2018
"The Tibetan plateau and Brahmaputra basin showed the largest increase during spring season with 0.2 °C/decade during 1971–2005 over northeast India and warming of 1.6°C across the north-western Himalayan region during 1901–2002,” added the study.
High temperatures result in increased moisture levels, according to Sandipan Mukherjee, another scientist at GB Pant National Institute of Himalayan Environment and Sustainable Development.
He added, “This moisture content then manifests itself in the form of either pre-monsoon thunderstorms in the Indo-Gangetic Plains or cloud bursts or hailstorms in mountainous regions like Uttarakhand.”
However, Mukherjee also said monitoring and observation have issues too that predictions inaccurate. “We do not have the equipment to measure rainfall and that’s why it becomes difficult to say if a particular extreme rainfall event is a cloud burst or not,” he said.
He also talked about the possibility of there being a link between forest fires and extreme rainfall events, although no study has been done so far to establish this correlation.
“Theoretically, it is can be said that forest fires and rainfalls are linked because fires give out a lot of smoke and other particulate matter which can aid rainfall if there is moisture in the air. This is the basic idea behind artificial rainfall. However, no studies have been done in India to test this,” he said.
According to the Uttarakhand Forest Department, 36 big fires were active in Chamoli before the cloudburst.