WILER, Switzerland (Reuters) -Residents struggled on Thursday to absorb the scale of devastation caused by a huge chunk of glacier that buried most of their picturesque Swiss village, in what scientists suspect is a dramatic example of climate change's impact on the Alps.

A deluge of ice, mud and rock crashed down a mountain on Wednesday, engulfing some 90% of the village of Blatten. Its 300 residents had already been evacuated earlier in May after part of the mountain behind the Birch Glacier began to crumble.

Rescue teams with search dogs and thermal drone scans have continued looking for a missing 64-year-old man but have found nothing. Local police suspended the search on Thursday afternoon, saying the debris mounds were too unstable for now.

As the Swiss army closely monitored the situation, some experts warned of the risks of flooding as vast mounds of debris almost two kilometers across are clogging the path of the River Lonza, causing a huge lake to swell amid the wreckage.

Swiss President Karin Keller-Sutter is returning early from high-level talks in Ireland due to the crisis, her office said.

"I don't want to talk just now. I lost everything yesterday. I hope you understand," said one middle-aged woman from Blatten, declining to give her name as she sat alone disconsolately in front of a church in the neighbouring village of Wiler.

Nearby, the road ran along the valley before ending abruptly at the mass of mud and debris now blanketing her own village. Just a few roofs poked up through the sea of sludge.

A thin cloud of dust hung in the air over the Kleines Nesthorn Mountain where the rockslide occurred while a helicopter buzzed overhead.

Werner Bellwald, a 65-year-old cultural studies expert, lost the wooden family house built in 1654 where he lived in Ried, a hamlet next to Blatten also wiped out by the deluge.

"You can't tell that there was ever a settlement there," he told Reuters. "Things happened there that no one here thought were possible."

'ENORMOUS PLUG'

But the immediate danger might not be over.

"The water from the River Lonza cannot flow down the valley because there is an enormous plug," Raphael Mayoraz, a cantonal geologist, told Swiss national broadcaster SRF, saying floods in downstream villages were a possibility.

Up to 1 million cubic meters of water are accumulating daily as a result of the debris damming up the river, said Christian Huggel, a professor of environment and climate at the University of Zurich.

Matthias Ebener, a spokesperson for local authorities, said that buildings which had emerged intact from the landslide are now flooded and that some residents of neighbouring villages had been evacuated as a precaution.

The army said in a statement that water pumps, diggers and other heavy equipment were on standby to provide relief when it was safe.

Authorities were airlifting livestock out of the area on Thursday, said Jonas Jeitziner, a local official in Wiler, as a few sheep scrambled out of a container lowered from a helicopter.

Asked how he felt about the future, he said, gazing at the debris: "Right now, the shock is so profound that one can't think about ityet."

The incident has revived concern about the impact of rising temperatures on Alpine permafrost which has long frozen gravel and boulders in place, creating new mountain hazards.

For years, the Birch Glacier has been creeping down the mountainside, pressured by shifting debris near the summit.

Matthias Huss, head of the Glacier Monitoring in Switzerland (GLAMOS), pointed to the likely influence of climate change in loosening the rock mass in the permafrost zone, which triggered the collapse.

"Unexpected things happen at places that we have not seen for hundredsofyears, most probably due to climate change," he told Reuters.

(Reporting by Dave Graham; Writing and additional reporting by Emma Farge in Geneva; Editing by Alison Williams, Gareth Jones and Mark Porter)