Italian officials have closed off roads and ordered mountain hut evacuations in response to expert warning that part of a glacier on Mont Blanc could collapse.
The mayor of Courmayeur, Stefano Miserocchi, ordered the safety provisions to be taken as experts said that a section of the glacier was sliding at speeds of 50-60cm (16-23in) per day.
Miserocchi said that global warming is changing the mountain.
“These phenomena once again show how the mountain is going through a period of major change due to climate factors and, therefore, it is particularly vulnerable,” he told Italian media.
Around 250,000 cubic metres of ice are in danger of breaking away from the Planpincieux glacier on the Grandes Jorasses peak.
Mont Blanc is Western Europe’s highest mountain range.
It has 11 peaks above 4,000m in France and Italy and attracts hundreds of thousands of tourists annually.
This comes as a new UN report is set to outline the impact that climate change is having on the world’s oceans - with millions in coastal communities facing flooding and sea level rise.
The latest special report from the Intergovernmental Panel on Climate Change (IPCC) has been launched on Wednesday, following the UN Climate Action Summit where countries met and discussed ways to avoid the worst impacts of global warming.
Attendees heard from teenage activist Greta Thunberg who set out the scale of the challenge in curbing emissions as she criticised world leaders for failing to take action, with the refrain: “How dare you?”
The new study, which examines the oceans, coasts and the cryosphere or frozen areas of the world, warns of huge increases in flooding damage, melting ice caps and glaciers and more ocean heatwaves that bleach and kill coral.
The world has already experienced 1C of warming which has made the oceans warmer and more acidic and affected fish stocks, while melting glaciers and ices sheets are causing sea levels to rise, the report says.
Hundreds of millions of people worldwide live in low-lying coastal areas, from villages to megacities, which face higher seas, more intense tropical cyclones and storms, extreme storm surges and flooding.
Many more live in high mountain areas affected by hazards caused by melting glaciers and ice, or downstream where water supplies and food security will be hit by changes to the frozen lands above.
More than 100 scientists from around the world have assessed the latest science about the role of climate change on ocean, coastal, polar and mountain systems, and the human communities that depend on them.
And an increase in extreme El Ninos – a weather phenomenon in the Pacific which pushes up global temperatures and can cause an increase in wildfires – is also on the cards.