Step one: Survive. Step two: Protect the planet

These three scientists are conducting vital research at the Earth's poles that will help us understand how our planet is changing — and they're pushing the boundaries of exploration in the process.

Human instinct would drive most people from a gaping hole in an ice sheet.

Especially as ferocious meltwater gushes into the seemingly bottomless cavity.

But for Professor Alun Hubbard, it's an irresistible invitation.

Originally from Wales, the glaciologist at Finland's University of Oulu has been studying Greenland's icy interior for three decades.

He's used to conducting research in "surreal and absurd" places to help us understand how our polar regions are changing — and therefore how the rest of the planet and the way we live on it is, too.

The Greenland ice sheet is one of Earth's two, continent-scale ice masses (the other being Antarctica). It's a powerful system that simultaneously reflects heat and stores water, helping keep the world's climate in balance.

Every summer, it sheds billions of tonnes of ice.

But, in recent years, that rate of loss has been accelerating to "unprecedented" levels.

Professor Hubbard believes there's a fossilised ancient forest inside the vast sinkhole that might offer clues as to why.

"As the base of the ice sheet thaws and more meltwater accesses it, [the forest is] starting to break down that organic matter and it's starting to leak methane," he says.

It's an educated guess that Professor Hubbard doesn't want to wait to test.

Not when he has a background in climbing and mountaineering, some rope, carabiners, and a team he trusts supporting him.

A short while later, the scientist dangles above the meltwater thundering down the shaft — which is called a moulin — equipped with a sensor that reveals the truth.

It is, indeed, expelling excess methane.

This discovery matters, because methane is a powerful accelerator in the climate system, capable of reducing the strength of even the most stable layers of ice.

If more of it's leaking from ice sheets like this one than previously thought, the climate models we use need to be updated to reflect that.

That's why Professor Hubbard decides to volunteer himself.

This time, he wants to feed a fibre optic cable through the rushing meltwater that will record temperature shifts in the depths of the ice below.

The findings are stark: the ice is apparently sitting at –4°C, when it should be between –18°C and –20°C.

According to Professor Hubbard, this has massive implications for projected sea-level rise.

The scientist knows his research matters, but it's also the "thrill" that keeps him coming back to work at the poles of the Earth.

"I feel far more comfortable on the Greenland ice sheet hanging off a rope than I would at a party," he says.

This isn't to say Professor Hubbard is unaware of what's ultimately at stake.

"If you screw up in that position, there is no chance of survival whatsoever … At least I know that if something goes badly awry, it'll be a quick one," he laughs.

The glaciologist is one of 15 researchers from across the world whose vital work is featured in the new documentary series, Ages of Ice.

Narrated by the dulcet tones of acclaimed Scottish actor David Tennant (Doctor Who, The Hack), Ages of Ice is a three-part program that follows a range of scientists including oceanographers and climatologists as they work on a diverse mix of projects in brutal conditions across the polar regions.

It would be remiss of the series not to feature stunning landscapes from Greenland to Antarctica, as well as the animals who call these places home.

But Ages of Ice isn't sanitised escapism masquerading as a nature documentary.

This year alone, we've seen devastating floods in Nepal, reports it might be too late to save places from Venice to Cocos (Keeling) Islands from rising sea levels, as well as a record El Niño forecast.

And it would be hard to forget the warning that the world is on track to breach the 1.5C global warming benchmark by 2030.

Writer, director and producer Karina Holden feels it's too late for "distracting forms of storytelling".

She wouldn't call Ages of Ice a "doomsday series", though.

"[Ages of Ice isn't] trying to make people feel scared or hopeless or depressed," Holden explains. "But we have to be realistic about what we are learning about the planet.

This sense of urgency is part of the reason Professor Hubbard allowed Holden and her crew to capture his descent into a nightmare-inducing moulin in Greenland in search of answers.

It's also why Dr Adrian McCallum agreed to have his arduous 600-kilometre data-collecting journey documented.

He may be working on the same ice sheet, but the geotechnical engineer and polar explorer from the University of the Sunshine Coast in Queensland is embarking on a very different project to Professor Hubbard.

Dr McCallum has just 30 days to trek across one of the most hostile environments on Earth with his crew of four other adventurers and scientists.

As if that wasn't enough, they must each pull 100-kilogram sleds behind them.

Behind Dr McCallum's sled is a ground-penetrating radar, collecting data.

"It projects energy into the ice sheet, which bounces off reflections within the ice sheet, [and] comes back to the surface. We can then work out how deep snow ice interfaces are," he explains.

From there, the hope is the team will be able to project what that might mean for sea-level rise.

But collecting the data involves a relentless month-long cycle of ice, wind and round-the-clock filming.

Every night, they must set up camp in a new stretch of the barren landscape and fall asleep with only a tent to protect them from the elements.

And in an extreme environment like this one, big weather events pose a serious risk.

With just 50 kilometres left to trek, Dr McCallum and his team face a storm — right when they're also about to run out of food.

To make it out before conditions turn deadly, they have to complete the final stretch of the journey in two days instead of the three they'd ordinarily allow for such a distance.

"I was very aware that if we did something wrong here, it could be the end of us," Dr McCallum says from the other side. "The winds were such that the helicopter couldn't get in.

"There were some very honest expressions shared amongst us."

Dr McCallum started training for the expedition a year out, running, cycling and pulling tyres behind himself twice a week. He was in the military for 20 years and has completed 10 polar expeditions in his lifetime.

He still wasn't ready for the reality of this trek.

"We're really surviving first, travelling second, and then thirdly, gathering data," Dr McCallum considers.

"You do need to like to suffer a little bit, or at least be prepared to suffer, because you will suffer.

"And you need to have something that's pulling you through that, that's driving you to do your work beyond the harshness of the environment."

For Dr Susanne Lockhart, the promise that her research has the power to help protect some of the most vulnerable life on Earth is what keeps her going.

Every summer, the independent marine biologist from Melbourne straps herself into a small submersible to find out what's living beneath the ice on the bottom of the seafloor in Antarctica.

The sub she's using to explore the depths of the Bellingshausen Sea this time is built to endure more than a tonne of force pressing on it.

"I've never been in a space capsule, but I can imagine that being in the submersible is very similar," Dr Lockhart says.

Teeming with starfish whose delicate arms stretch out in conversation with each other, sponges believed to be over 1,000 years old, and delicately rippled Nudibranchs, much of the Benthic zone where Dr Lockhart works feels like an alien world.

For almost three decades, the marine biologist has been trying to prove how vital these poorly understood Antarctic worlds are to our planet; we now know fragile ecosystems like this one help maintain the balance of the entire Southern Ocean, on which 10,000 known species depend.

"The invertebrates on the sea floor take carbon that falls from krill and other organisms, and put it back into the sediment, which is what we want," Dr Lockhart explains.

"We need it to go back into the earth to balance things out."

Because of Dr Lockhart's work, more than 500 square kilometres of the Antarctic seafloor have been declared permanently off limits to commercial trawlers fishing for krill, whose activity threatens the existence of these fragile worlds.

Once she's returned to the surface, Dr Lockhart must face what scares her far more than travelling so far below the ice: the possibility she won't be able to make as much of a difference as she'd like before it's too late.

The state of the planet frequently induces feelings of depression and fears of futility in many of the scientists featured in Ages of Ice.

So do the global politics that constrain their research and the implementation of their many and varied recommendations.

And yet, they each still ultimately have hope.

"I still think we have to try and make our voices heard," Professor Hubbard begins.

"People may think there's no point. But every tonne of CO2 that we can stop from going into the atmosphere, if we can really focus on getting to carbon neutral within 10, 20 years, we really do avoid a major catastrophe."

We've got a story for you. Stream Ages of Ice on ABC iview or watch on Tuesdays at 8:00pm from November 3 on ABC TV.