For tourists visiting from around the world, the Rifugio Guide del Cervino offers a break from winter sports for food, drinks, lodging, and as this reviewer called it: "A great Italian experience."

But something unexpected is happening here.

The nearby Theodul Glacier is melting.

And as it does, this little Italian ski lodge is on the verge of moving into Switzerland.

Most of Italy's land border follows the watershed along the Alps.

There is this imaginary line that divides the water that falls in the Mediterranean Sea in the south.

Or in the north, they go into the Black Sea via the Dunabe. Or to the North Sea.

That's Marco Ferrari. He wrote a book about this border with architect, Andrea Bagnato and visual designer, Elisa Pasqual.

This watershed line traces many of the highest peaks of the Alps, forming a natural border between countries.

Much of it is marked by over 8,000 boundary stones like these.

Some of which have been around since the 16th century.

But in the most rugged terrain, where physical markers are few and far between,

Swiss, Italian, and Austrian cartographic agencies have long maintained official border records with meticulous measurements and annotated pictures like these.

Some of these areas are on top of glaciers. Their surfaces are too reflective for satellites which are often used to measure borders.

The work by the surveyors is done manually.

So every few years, there's a commission of surveyors composed of members of both countries that actually walk the border and look how it has changed.

As early as the 1920s, surveyors noticed a "slow but progressive" shrinking among glaciers, and that "some had disappeared."

But by the 1990s, it became clear that summer melt had outpaced winter accumulation.

The surveyors realized that the glaciers were melting and not accumulating ice anymore.

This kind of cyclical change in the shape and geometry of the watershed became more and more permanent.

And as glaciers shifted, so did the watershed and so did the border.

Here's what that looks like.

On many Alpine peaks, a glacier ridge forms the watershed boundary line and thus the national border.

But as those glaciers melt, their highest point might shift, often dozens of meters away.

If they melt far enough, they even reveal underlying rock peaks which then become the border line.

These black X's mark the old national boundary between Italy and Switzerland.

But if you trace today's national boundary and compare it to old maps, you can see all the places where the boundary line has moved.

In the most extreme case yet in the Alps, shifts in the Theodul Glacier moved the border 150 meters.

That put this Italian ski lift on Swiss soil.

And the Rifugio Guide del Cervino might be next.

Typically when countries renegotiate borders, there's a careful process to make sure that neither country gains territory at the other's expense.

But recently, Italy signed a new type of agreement.

First with Austria in 2006, and then with Switzerland in 2009 that recognized the Alps as a "mobile border."

Acknowledging that the border was subject to changes in the natural world outside of those countries' control.

Fortunately, the Rifugio is the only inhabited place along this shifting border.

And if it becomes Swiss, it'll be subject to Swiss law, taxes, and customs.

They might have to change their wall plugs.

But for most nearby residents, the changes won't mean much.

But if we think about different areas of the world where similar processes are happening, for example, the Himalaya or the Andes,

these are completely different geopolitical situations in which also the scale of the phenomenon is much, much bigger, the histories are much more conflicted.

In the Himalayas, China and India disagree about their border and have fought several times over it as it continues to melt and shift.

And in the Andes, Chile and Argentina have long disagreed about their own melting border.

As climate change warms the planet and moves water-based borders, these conflicts could worsen.

Rivers, which make up over a third of the length of all international land boundaries, will be subject to extreme events that can change their course.

Coastlines will give way to rising seas, affecting exclusive economic zones, where a country's sovereignty extends into the ocean.

And glaciers, like in the Alps, will continue to melt.

The alpine mobile border is almost like a laboratory, a prototype of a condition that will happen more and more in a lot of different parts of the world.

Keep going!