Scientists ponder reasons for Uttarakhand floods Climate change, Western disturbance, or both?

Global warming or maybe a Western disturbance bringing fresh snow that melted could have triggered the inundation in Uttarakhand's Chamoli district, experts said on Monday as they scrambled to understand the reasons for the avalanche and floods that wreaked havoc in the upper reaches of the Himalayas.

The Snow and Avalanche Study Establishment (SASE) of the Defence Research and Development Organisation is investigating the exact reason for the flooding but there are no clear answers yet for a glacier to have melted in the winter.

It is not clear whether the flood is a typical Glacial Lake Outburst Flood (GLOF) or some temporary damming due to a landslide and avalanche that might have blocked the mainstream to form a temporary lake which burst, said Ranjit Rath, director general of the Geological Survey of India (GSI).

A GLOF is a type of outburst flood that occurs when the dam containing a glacial lake fails.

"Once the water level recedes a team of experts will assess the damage as well as the triggering factor responsible for the outburst," Rath told reporters here.

As the nightmare envisaged by numerous environmentalists warning against untrammeled development in the mountains came true on Sunday, glaciologist Farooq Azam said a glacial burst is very rare.

"We have been trying to understand the event since yesterday. Right now what we can tell is a glacier slipped from around 500-600 metres, which started a landslide with an icefall that triggered this disaster," Azam, assistant professor, Glaciology & Hydrology, Indian Institute of Technology (IIT), Indore, told PTI.

Climate scientist Roxy Mathew Koll agreed and also said more data is needed.

Koll said it was not clear if an accumulation of glacier melt led to this burst, and noted that Western disturbances during last week did bring in a lot of snow over the region, followed by clear sky and warm temperatures.