- The British Antarctic survey (dramatic music) just dropped the most detailed map ever of what's underneath the ice in Antarctica.

And my mind is blown because I had no idea it was like this: enormous mountain ranges and valleys island chains, and massive rivers and lakes.

And it turns out there's even an ancient alien ecosystem down there.

We didn't know about almost any of this until the last few decades because it's hidden by an ice sheet that's on average over 2 kilometers thick, which is basically just 34 million years of accumulated snowfall, which is enough to raise the world's oceans by 190 feet if it melts.

(dramatic music continues) Accelerated ocean warming has already locked in drastic melting of the West Antarctic Ice Sheet.

And new evidence shows that total collapse might be more imminent than we once thought.

And there's something else hidden under the ice that may speed up the melt that we're just now beginning to understand.

This is the Ring of Fire, a massive horseshoe-shaped zone where most of the world's earthquakes and volcanic eruptions occur.

It marks the edges of tectonic plates where one plate dives beneath another in what's called the seduction zone.

But what the map doesn't show is that West Antarctica is possibly the largest volcanic region on Earth.

Antarctica isn't technically part of the Ring of Fire because it's a roof system rather than a subduction zone, but over 100 volcanoes have been identified there, most of them buried under kilometers of ice, which raises some big questions.

What happens when a volcano erupts beneath thousands of feet of ice?

And what does that mean for the stability of the West Antarctic Ice Sheet, which holds enough water to cause 5 meters of sea level rise?

I set out to find the answers, and what I found is that it's not just possible, it could actually trigger a dangerous feedback loop, something that we've seen before.

So stay tuned because there's some unexpected and cute new evidence that the future of West Antarctica is even more precarious than we once thought.

(dramatic music continues) Antarctica remains one of the most mysterious places on Earth, and is also a source of deep curiosity for scientists, especially when it comes to what lies beneath the ice.

- We do know more about the surface of Mars than we know about the subglacial environment in Antarctica.

- But thanks to some really cool technologies like seismic surveys, ice-penetrating radar, and satellite gravity mapping, researchers have begun to assemble an increasingly detailed image of this alien world, and what they found is shocking.

- [John] If you were to take that ice sheet off, you'd see a mosaic of 2-mile high mountains, deep trenches, and valleys and rivers.

Some of the rivers are larger than surface area than the Amazon.

- [Maiya] And they've also found hundreds of lakes, so you might be wondering the same thing I was.

In the coldest place on Earth, where temperatures reach 70 degrees Fahrenheit below 0, how is there so much water?

- There's three main reasons.

You have this thick ice sheet, which insulates the bottom of the ice sheet from the very cold atmosphere, and then the mass of the ice sheet puts pressure on the bottom, which reduces the freezing point of water.

And we all know that the Earth has this molten core, so there's heat down there.

So that little bit of heat combined with that reduced freezing point and that nice insulating blanket gives you a really unique habitat for liquid water.

- Starting in the '50s, aerial and seismic surveys added support to the idea of a lake under the ice.

And then while the Soviets were drilling for climate data, they hit some funny ice.

And this is ice that didn't appear to have been layered over time, like the normal glacial ice formed from falling snow.

- And they kind of stopped drilling and the international community all joined in and had a discussion about this ice.

And the conclusion was it was water that had frozen onto the bottom of the ice sheet from the lake.

- [Maiya] And this lake, which is about 2 miles beneath the ice, is called Lake Vostok.

And it turned out to be remarkable for many reasons.

- Well, it's one of the largest lakes on our planet.

It's over 3,000-feet deep, and it's about size of Lake Ontario, and it's been liquid probably for 15 million years.

And then that led to, "Maybe there's more lakes," and all of a sudden countries all over the world joined in, that right now we know there's almost 700 lakes under the ice sheet.

- Of these nearly 700 subglacial lakes, scientists have only been able to sample a few so far, and what they found there beneath nearly a kilometer of ice completely changed how we think about Antarctica.

- Everybody thought the Antarctic cont was just a big benign block of ice.

There was no liquid water.

The only life were this prismatic megafauna around the edges of the continent like seals, and penguins, and shore birds, et cetera.

- John and his team drilled down into two lakes, Lake Whillans and Lake Mercer, and they found life.

And not just fossilized life, but living microbial life, thriving in total darkness under immense pressure in the coldest place on Earth.

- I'll never forget it, it kind of changed my life.

- And there's another reason these subglacial lakes and water systems are important, and it has to do with climate change.

- When this water pools under the ice sheet, it lubricates the bottom of the ice sheet and leading to rapid flow to the ocean.

The glaciologists now are revising their ice sheet models to include this liquid water underneath.

- Scientists once thought the West Antarctic Ice Sheet was hundreds of years from collapse, but a growing body of research suggests that it may happen a lot sooner.

And that loss isn't mainly from melting at the surface, it's from below.

Warm ocean water seeps underneath the ice shelves, melting them from the bottom, and creating a kind of lubricated bed that allows massive glaciers to slide more quickly into the sea.

- And when those glaciers go, that ice can just flow very quickly to the ocean and sea level can rise in decades really quickly.

- And as I mentioned earlier, West Antarctica also happens to sit on a volcanically active rift system, and this is where things really get strange.

(dramatic music continues) - Over a hundred volcanoes have been identified already.

Some of these are exposed so visible at the surface, and then the majority of them are buried underneath the ice.

- Which brings us back to my original question, what happens when a volcano erupts under thousands of feet of ice?

And does this volcanic activity further threaten the already imperiled West Antarctic Ice Sheet?

- When volcano erupts underneath an ice sheet, hot magma is put in contact with ice, and this heat can be used to melt the ice.

And if you have liquid water underneath an ice sheet, this can significantly reduce the friction associated with the ice sheet against the bedrock.

- And that can allow the ice sheet to slide much faster into the ocean.

But perhaps my original question isn't the right question at all because there's a different interaction that's happening between the ice and volcanoes that could be much more significant, and it has to do with how climate change is amplifying the effects of these volcanoes.

Allie's team developed a physical model of a magma chamber that's within Earth's crust beneath an ice sheet, and they found that the volcanoes themselves are sensitive to the rate at which ice is removed overhead.

- Ice sheet removal can trigger additional eruptions that would not have otherwise occurred, and these additional eruptions could be larger.

- And I can't imagine that more and bigger eruptions under Antarctica's already compromised ice sheet is a good thing.

- [Allie] That's the worst possible place that you could put water if you're trying to slow down the loss of ice.

- This could trigger a dangerous feedback loop where eruptions trigger more melting, which triggers more eruptions.

And what I really wanna know is if we've seen evidence of anything like this happening before.

And to find an answer, we don't have to look any further than the last ice age in the South Andes.

- [Allie] Basically what we see in the Southern Andean Volcanic Zone is an increase in the frequency of eruptions and the total amount of erupted material along the times of most rapid ice loss.

- Another strong argument for this link between glaciation and volcanic activity is how Earth transitioned out of so-called snowball Earth events hundreds of millions of years ago.

And these are periods where ice covered all or most of our planet.

- As you cover the entire globe with ice, the surface becomes very reflective.

As the ice grows, it reflects more radiation from the sun, and that only promotes further ice growth.

It's an unstable feedback.

- If the entire Earth was covered in ice, how did we get out of that to an Earth that's more similar to present day?

- Really, the only prevailing theory is that there is a feedback between volcanism and deglaciation.

Volcanic activity was still going on underneath this glaciated planet, and then that causes ice to melt, which in turn affects the volcanic activity below until you can melt enough ice to revert to a modern climate state.

- So far, the West Antarctic Ice Sheet has only contributed a few millimeters of sea level rise, but these new findings add to a growing body of research warning that near total collapse is much more likely than we once thought, and could happen as soon as 2300.

And one more piece of evidence added to this theory, and it came from an unusual source, octopus DNA.

- So DNA is like a time capsule of the past.

So anything alive today contains information about their ancestors' past.

And through modern genomic techniques, we can utilize this information and look into patterns of genetic mixings in the past.

So for our project, we use octopus DNA to understand whether the West Antarctic Ice Sheet had experienced mass loss during the last interglacial.

- DNA analysis showed that isolated populations of this tiny octopus mated around 125,000 years ago, something that wouldn't have been possible unless the Weddell Sea and Ross Sea were connected.

This adds to growing evidence that during the last interglacial when temperatures were similar to today, the West Antarctic Ice Sheet collapsed and sea levels were as much as 10 meters higher than today.

(dramatic music continues) All of this, the potential feedback loop of volcanic eruption triggering ice melt, causing more volcanic activity, lakes under the ice contributing to more melt, and evidence that the ice sheets are a lot more unstable than we once thought is concerning.

The future of sea level rise remains uncertain, but research continues to show that the decisions made today will influence how that future unfolds.

I'll certainly be staying informed as scientists closely watch these developments to better understand what lies ahead.