By Navin Singh Khadka
BBC News, in Nepal
Already experiencing melting glaciers and a receding snowline, the Everest region of Nepal has seen some unusual weather patterns these past few months.
A dry winter has been followed by a snowy spring
It has given locals further cause to examine the changing face of this unique environment.
A snow-free winter, followed by unexpected snow storms in the second week of March - when spring had already begun - has left Sherpas baffled.
Another unexpected storm in April, which lasted three days, surprised the locals further still. The following morning, on 21 April, debris from a major ice collapse killed three Sherpa climbers and injured more than a dozen others in the Khumbu Ice Fall area.
Such accidents are not uncommon in mountaineering, but this one was blamed on the unusual snowfall which was believed to have caused the collapse of the ice mass.
"We don't remember getting such snowfall during spring in the past," said Manmohan Singh Chhetri of Asian Trekking, which had employed the Sherpa climbers.
"This accident had much to do with the sudden change in the weather patterns in the Everest region. Perhaps this is what global warming is all about."
Even local Sherpas say heavy snowfall in spring is something they are not used to. Moreover, the snowstorms occurred after a completely dry winter period, lasting from November to February.
"Last winter was not at all like winter, and now the same is the case with spring," said Jangbu Sherpa, an 80-year-old Sherpa from mountain town Namche, which is en route to the Everest base camp.
"This is something we've never seen before. We think this is quite ominous."
In the last two months, many trekkers have been caught unprepared by the unexpected snowfall, forcing some to return while keeping others indoors.
"The guidebooks I referred to did not have any information about snowfall in this season," said Sarah Topping, a trekker from London, after she braved a sudden snowfall around Namche last month.
The locals are just as surprised. "I have taken all my jackets out of the wardrobes again, even though I had put them away last February," said Nawang Sherpa, a lodge owner in Namche.
For locals dependent on farming, the unusual snowfall in spring brought relief.
Heavy snowfall in Namche during spring surprised locals
"We were quite frustrated because the wintry months were dry and we could not grow anything," said Sarki Maya Tamang, a farmer in Lukla, the gateway to the Everest region.
"Now that it has snowed, the fields have become wet and we can sow barley."
Conservation organisations such as WWF have also taken note of the unusual weather patterns.
"We have noticed the unusual and unexpected snowfall in spring," WWF's climate change officer, Sandeep Chamling Rai, said. "We have been receiving complaints from locals about the changing weather pattern."
Rangers in the Sagarmatha National Park echo the same message: "All we can say at this point is climate change is happening the world over and the Everest region cannot be an exception," said a spokesperson.
This region has now become the subject of intensive study, to get some concrete data rather than just people's perceptions of changing climate.
EV-K2-CNR, an international organisation with headquarters in Italy, has recently installed a sunphotometer at an altitude of 5,079m (16,600ft) near Mount Everest. It will monitor atmospheric aerosols, "brown clouds" and changes in humidity in the Himalayas.
"Atmospheric aerosols are 'powders' that can prevent sunlight from reaching the Earth's surface, and they can also warm the air layer. They have impacts in both regional and global climate," explained a spokesperson from EV-K2-CNR. "They can lead to changes in temperature and rainfall patterns."
While the findings of the sunphotometer are awaited, Nepal's Department of Hydrology and Meteorology says it has an explanation as to why it did not snow at all in most of the Nepalese Himalayas last winter.
"The information we have is that the westerly disturbances that normally arrive in the atmosphere of Nepal during winter did not happen this time due to atmospheric pressure reasons," said Sarju Baidya, senior divisional meteorologist at the department.
"The westerly disturbances this time went to Tibet without entering Nepal's atmosphere, and that was the reason why there was no rain throughout Nepal last winter and there was no snow in the mountain region."
Technocrats like Baidya may have the answer for the dry winter but they do not, as yet, have an explanation for the unusually snowy spring the Everest region has witnessed this time.