Transcript for What glaciers on Mont Blanc, Europe's tallest mountain, reveal about climate change
a melting landscape. The highest peak to the right is the very top of mount blanc. Reporter: It's the highest mountain in western Europe, spanning three countries, mount blanc, soaring over the world-famous alps. We travel by helicopter to reach mount blanc's glacier, about 10,000 feet up. Remarkable up here. You do get a sense of just how much is changing and how fast. These deep cracks represent our planet's latest climate change battleground. We often think of climate change as taking place on the outer reaches of our world, Greenland, Antarctica, islands in the Indian ocean. But what's happening here on mount blanc shows that the changes are happening much closer to home. The glacier on the Italian side of the mountain is breaking apart significantly faster than expected and could collapse at any moment, sending ice crashing into the town below. How fast is too fast, if you because all glaciers move. Of course. But this glacier is moving quicker? Enormous speed for this glacier. Would be about 10 centimeters per day. Right now peaks at 1 meter per day so 10 times. It's moving 10 times as fast as it should be? Yeah, yeah. Reporter: Why? A warming climate, say 66 million gallons at risk of collapse. That's about 100 frozen olympic swimming pools. This scientist monitors and studies the changing glaciers in the region. So this is it? This is where you do your work? He took us to his office in the outskirts of the area which sits directly underneath the glacier we flew over. Right now the different scenarios say the glacier will disappear under 3,500 meters. Which means the alps will have just maybe one-third or less of the glaciers that they have today. You could lose two-thirds of the glaciers? Almost everything will disappear by 2100. That's just 80 years. Yeah, it is. Reporter: He shows stark images of how a nearby glacier has changed over the past decade. 2004, there's still quite a lot of ice coming down and coming down in this flat area. But if we go to 2017, in just a few years, all this ice has disappeared and gone back up here in the rocks. A small bit of ice. The change is really drastic. Reporter: He warns if we don't continue to make change, it could get much worse. We are working and will work more and more to let people know about the effects of climate change. If everybody will do this around the world, it would be a good point to start. Reporter: The falling ice from mount blanc, a dangerous hazard. Water supplies for millions drying up. Livelihoods in the balance. This danger zone now evacuated. A main road closed. People here insist life will go on. Their experience is not isolated, it's one of many melting glaciers around the world. Earlier this year I traveled to antarctic ka, ground zero for climate change. We have 12 years to fight the impacts of climate change. We have to act now. Reporter: The frozen continent too harsh for humans struggling to cope with a human-altered climate. Good morning. Welcome to Antarctica. Reporter: Across the peninsula the ice season has shortened by more than three months over the last 40 years, and 87% of the glaciers here are receding. It's not just glaciers. The animals threatened as well. Today we're going to look for humpback whales, minke whales. We want to biopsy and fly our drone over them to look at body condition and size. Yeah, I see it, yeah, right there. It's up now. Reporter: These marine biologists have come from all over the United States to Antarctica to study the pressures facing the humpback and minke whale populations. Biopsy samples are taken using a cross bow. This is the tip that will collect the skin and blubber sample from the whale. It will penetrate an inch, inch and a half into the whale and get some skin and blubber. This first sample we took for pollutant analysis. This sample can't go into the plastic sterile baggies because one of the contaminants we're looking for is plastic contaminants. Reporter: Contaminants have made their way into the whales' bodies, tendrils of man making their way into the seemingly pristine waters of Antarctica. We're presenting issueses of life and death and they are often really serious. Being here, learning about the science, you get the sense this really is life or death. For all of us. From Antarctica to the alps -- It really is a marker of what may be to come if the pace of global warming accelerates or even stays where it is at this point. Reporter: A striking reminder of what's at stake. For "Nightline," I'm James long money in mount blanc.
This transcript has been automatically generated and may not be 100% accurate.