"All the Himalayan glaciers are melting, an average of 10-20m a year," he says.
One of the most obvious changes, he adds, is the growth of what are known as glacial lake outburst floods (glofs).
"A glof happens when a glacial lake is created by a melting glacier and it then bursts. Imja lake is the most dramatic example of a potential one. It is growing 74m a year. When it bursts its banks, we will have a mountain tsunami. Billions of gallons of water will be released and it could wipe out about 70% of the trekking trail to Everest base camp. Not only will that destroy our homes and potentially kill people, but it will wipe out the jewel in the crown of Nepal's tourism industry," he says. -Guardian.co.uk