Lalpani is not an isolated pocket. It's the same with the rest of the Himalayas. Tourists tend to mindlessly leave behind huge mounds of polythene bags, glass, metal, coal residue, juice wrappers, processed leather, empty oxygen cylinders and ash.

Can the thoughtlessly tossed juice cans or plastic bags add up to something bigger? Scientists say yes.

"Non-biodegradable waste absorbs heat which results in temperature rise that can melt glaciers to form new glacial lakes. These lakes pose the threat of glacial lake outburst flood (GLOF). But we don't know when the lakes could burst," says Prof RK Ganjoo, a Jammu University specialist in quaternary geomorphology, climate change and glaciology.

The Hindu Kush-Himalayan region stores more snow and ice than any other part of the world outside the polar regions (thus the name 'the third pole'). The Nepal Himalayas, on the other hand, occupy 800 km of the central section of the Himalayan range and the Indian stretch has more than 5,000 glaciers of different sizes and shapes.

Experts say that continuous storage of huge quantities of water has turned these lakes on high mountains into potential "water bombs" for the population living downstream in Uttarakhand, Himachal Pradesh and Nepal.

There are 249 glacial lakes in HP and 11 have been identified as ones with potential risk of breaching. Experts said that these lakes need regular monitoring. "A lake burst would cause flash floods which could sweep away people, houses, roads and bridges in Nepal, Bhutan, Bangladesh and India," says a recent report prepared by Himachal Pradesh government.

The increase in atmospheric temperatures is the main reason for higher melt rates of glaciers. Though waste is not the biggest reason for such increase, it is a contributor. In the last century, the north-western Himalayan region has witnessed 1.6 degrees celsius rise in temperature. Winter discharge in Chenab river has shown significant increase while Satluj river too is showing increasing trend of discharge during winter and spring.

A report by the HP department of science environment and technology says an overall reduction in glacier area from 2,077 sq km to 1,628 sq km from 1962-2001 has been recorded in Chenab, Parbati and Baspa basins — a loss of 21% of glaciers.

Scientists chiefly blame tourism for the situation. "In 2005, non-biodegradable waste was 16.9% of total waste in Manali and 34.8% in Kullu. In and around the Valley of Flowers and the Pindari valley in Uttarakhand, such waste comprised 84.5% and 66.4% of the total waste generated. It is evident that nonbiodegradable waste is much higher in trekking and expedition locations than the down-slope hill spots," says JC Kuniyal, senior scientist at GB Pant Institute of Himalayan Environment and Development, Mohal in Kullu.

The Himachal government, in 2011, imposed blanket ban on the use and storage of non-biodegradable disposable plastic cups, plates and glasses and warned violators of a fine of up to Rs 5,000. But these measures don't seem to working very effectively.