The Hunt for Answers Beneath Antarctica’s Ice

Why drilling 2-kilometre ice holes and unlocking the hidden environments beneath may give answers to big questions about the past, the future – and even life on other planets.

By Simon Ingram
Published 19 Mar 2019, 10:54 GMT, Updated 27 Apr 2021, 16:33 BST
Much of Antarctica is below hundreds – or even thousands – of metres of ice, much ...
Much of Antarctica is below hundreds – or even thousands – of metres of ice, much of it millions of years old.
Photograph by María Stenzel, National Geographic

IT TOOK 63 continuous hours for the British Antarctic Survey to drill 2,152 metres to the bottom of the Rutford Ice Stream – a 290km-long slab of ancient ice that sits in a trough beneath the highest mountain range in Antarctica. As these things go, that’s fast. 

The hole was made using a technique called hot water drilling. The process involves melting a large supply of water from the surrounding ice, pumping it through heaters until just below boiling point, then running it into a specially-made, continuous 2.3km hose. Amidst the background whine of generators, the hose is lowered into a pilot hole in the ice. The hot water then starts to flow, deepening the hole at between one and two metres per minute. A pump recovers the excess water, re-heats it, then pumps it back into the hole, widening it to a diameter of 30cm – about the length of a typical school ruler. 

If that sounds easy enough, hang on. Heating water to boiling point when the surface temperature is around minus 30 deg C requires some serious hardware. Keeping water liquid at these temperatures is to continually fight physics, and once the hot water drill is extracted, any hole in the ice re-freezes at around half a centimetre an hour, meaning you have a to get in and out with instrumentation lines before the door very literally closes on you. A 2.3 km hose isn’t easy to come by either – particularly when you need it in one single piece, due to the proclivity of joints to freeze or fail at critical moments, as happened to the same project in 2004. Getting the whole rig out to your drilling site involves moving it to a location 1300km away from the nearest permanently-occupied research station. And then, Antarctica has the habit of often combining extreme cold with storms.

Bad weather forced the survey team into retreat during the first weeks of the season - followed by periods of digging equipment out.
Photograph by Paul Anker, British Antarctic Survey

“They had a particularly bad start to the season,” Dr Keith Makinson of the British Antarctic Survey told National Geographic UK from the institute’s office in Cambridge. “They had about four or five quite severe storms at the site, so they lost well over two weeks just hunkering down during the storms. And then digging all of the equipment out.”

All challenges which made the three holes now drilled by the 11-strong British Antarctic Survey team as part of the BEAMISH project – the first on the 8th January, with a second following on the 22nd and third on February 10th – an impressive result.

The project has been hailed as a breakthrough in more ways than one – the successful opening of a hole from the top to the bottom of a thick ice sheet, and the first time a hot water drill has been used for an access hole to this depth. Now attention turns to what the deployment of instruments into the ice could tell scientists about the world of the past, the changing world of today – and even worlds that aren’t our own. But what is it about ice that makes it such a rich medium for study?

The British Antarctic Survey's BEAMISH team's base on the Rutford Ice Stream.
Photograph by Paul Anker, British Antarctic Survey

The White Desert

Ice has been a feature of Antarctica for millions of years, though precisely how long isn’t fully understood. It is thought the continent’s ice sheets began to form during the Eocene, and grew extensively during a period of global cooling around 35 million years ago. During the earth’s last global glacial period around 18,000 years ago, the Pleistocene, the ice sheet reached its greatest size. Today, with Greenland’s, it is one of only two left on earth. 99% of the world’s fresh water lies locked in the ice. If the sheets were to totally melt, sea levels would rise by over 60 metres globally. (Read about how ice sheets form.)

A combination of retreating ice and the resulting rising seas, this is a visualisation of what Antarctica may look like if its ice sheet melted entirely.

In terms of size, the two sheets are far from comparable. Antarctica’s covers 14 million square kilometres, and is divided into three: East Antarctic Ice Sheet, the Antarctic Peninsula and the West Antarctic Ice Sheet. The BEAMISH team’s focus on the West Antarctic is in an area specified as an ‘ice stream’ – a region of fast moving ice, caused by subglacial melting. Like a giant glacier, heading for the ocean, above an hidden landscape far below. 

Paul Rose, a British explorer and National Geographic Pristine Seas Expedition leader, was for 10 years the Base Commander of the British Antarctic Survey’s Rothera Research Station. “In Antarctica there’s a massive sense of a wild, pristine place,” he says, “but you do have to remind yourself, driving along on a skidoo in a straight line for weeks and weeks, that you’re on a mile-deep piece of ice. That’s the great thing about these places: they do require a bit of imagination to understand.”  

Science to the core

Ice drilling is nothing new – and it’s usually the ice itself that has been the object of attention. Ice core samples are the conventional product of polar drilling, and the extraction of these long cylinders of frozen history has led to some of the most insightful glimpses into our past environment. 

“I like to say, ice cores don’t lie,” says Dr Paul Mayewski, Director of the Climate Change Institute at the University of Maine. Mayewski describes Antarctica as like a "second home", after spending a total of four years on the ice – much of it off-base in a field tent. “People used to believe that because it was a big mass of ice, if you had once ice core you understood everything about it. But there’s a lot to understand.

“By using various techniques, you can tell how far an air mass travelled, the source of that air mass, emissions, volcanic events, whether or not human pollutants have changed over time, biological productivity, past temperatures. We measure about a hundred different chemical properties." Mayewski continues. "The information is there, and if you don’t believe it maybe you go and collect a couple more [to compare], and sure enough. You can get more from an ice core than from any monitoring station. The problem is they’re hard to get – and you don’t get too many of them.” 

So ice cores are like a frozen stratigraphy stretching back thousands, or even hundreds of thousands of years – into which climate history is infused like a chemical time-stamp. This has revealed some worrying and peculiar human-led trends. 

“In the drilling that we did in the Swiss-Italian Alps recently, we noticed that in 1348 – the beginning of the Black Death – that the lead levels dropped to almost zero,” says Mayewski. “And that’s because half the population of Europe was dead. Mining stopped, smelting stopped – so that means that when human activity stops, the levels of lead in the atmosphere should be close to zero. Which completely changes our view of what health standards should be.

“And lead’s not the only thing. Cadmium, all sorts of things that cause cancer, arsenic – people know what these things do. They just had no way of knowing, until ice cores existed, that what we live in today is very different. The chemistry of our atmosphere today is unparalleled in the last 800,000 years – and there’s no reason to presume it isn’t unparalleled in millions of years, prior to human involvement. Based on ice cores alone.”

So that’s the ice itself. But what of the land beneath it? That’s where this next phase of Antarctic exploration is destined to venture. 

A close up of an Antarctica ice core, showing evidence of bacteria and sediment matter.
Photograph by María Stenzel, National Geographic

What lies beneath

“The main reason for hot-water drilling being developed is really about speed,” says Keith Makinson. “It offers quick access. When I started doing this back in the 1980s, we were drilling through just a few hundred metres of ice – but we could do it in maybe 8 or 10 hours, whereas with conventional ice coring equipment that might take several weeks.”

BEAMISH stands for Bed Access, Monitoring and Ice Sheet History. The project’s target: the sediment at the base of the Rutford ice stream. Every centimetre unfrozen is a step back in time until you hit paydirt: the ground beneath, sealed off from the world for as long as the ice has been there.  Extracted elements and isotopes contained in sediment can help with dating and therefore a figure for when the landscape was last free of ice can be obtained. But that’s really only the start of it.

Scientists know relatively little about what the landscape of Antarctica is like beneath the ice. Cores are one thing, but samples from the ground itself remain fiercely difficult to obtain given that most of it sits below thousands of metres of frozen, immovable water. In addition, the depth the holes have reached before emerging out of the ice lies hundreds of metres below the present sea level. This means the sediment the team has hit isn’t the ‘surface’ of Antarctica, but the bed of a now-frozen sea channel that once ran through it, linking parts of the ancient continent by water in the time before the ice.   

“From a drilling perspective it’s the technical challenge of doing this work – overcoming the environmental challenges and getting technology that will work reliably down there,” says Makinson. “And the feeling you get when you know you’ve broken through the base of the ice to create an access hole – that’s a pretty special moment.”

The holes drilled by the BEAMISH team aren’t the deepest made by hot water drilling. In 2005 an American team based at the South Pole station managed a depth of 2,450m and a diameter of 60cm for the installation of a neutrino telescope and monitoring equipment – but these didn’t reach the base of the ice. This makes the BEAMISH holes the deepest hot water drilled subglacial access holes – essentially one that pokes out the bottom of the ice allowing samples to be collected from beneath.

Instruments are lowered into the cavity in the Rutford Ice Stream.
Photograph by Paul Anker, British Antarctic Survey

Liquid lakes – under miles of ice

“All ice sheets are pretty poorly explored,” continues Makinson. “Though we do have some idea of what the landscape looks like. We rely heavily on radar measurements, particularly from aircraft to reveal the large-scale topography that we find underneath them, so you’ll pick up the large valleys, mountain ranges and such. But the [radar] grids are quite coarse.”

Exploring what lies beneath the ice is one of the key drivers for the BEAMISH drilling project. As well as ancient valleys and traces of the early landscape before the ice, subglacial melting has produced water, some of which has pooled into lakes and filled cavities that may have been there since before the ice sheets arrived. Entered existing lakes, even – containing water that might be there still.  

The idea of liquid water beneath kilometres of ice seems remarkable. But temperatures are both warmer below the ice than at the surface due to geothermal activity in the crust, and rather good insulation by the thousands of metres of ice above. This has raised some tantalising prospects for polar scientists – the chance to study a body of water, any remains that might be found there, and sediments locked away from light and disturbance for hundreds of thousands, or possibly millions of years. The problem is accessing it.

“There’s a whole scientific community waiting for the engineering to be developed so that we can access these lakes and look at the microbial communities within them – and obtain a sediment core that is dateable,” says Makinson. “A core from a lake of a few metres long is like tree rings – you might have a history of many tens of thousands of years contained within it.” 

“That’s the great thing about these places: they do require a bit of imagination to understand. ”

Paul Rose

It is thought there are hundreds of sub-glacial lakes in Antarctica. The most mythologised of these is Lake Vostok, a 143-mile long sub-glacial colossus in East Antarctica, which lies under nearly 4,000m of ice and is thought to be 1,000m deep. Its existence was discovered by radar in 1996 by a team of British-Russian scientists. Its volume makes it one of the largest lakes on earth.

In 2012 a Russian team succeeded in creating a borehole down to Vostok, a record depth of 3769m using conventional drilling, but it was a costly and lengthy process. The drilling took almost two decades, and was dogged by glitches: machinery failed, the hole re-froze and the ice fractured in ways that blocked progress, often agonisingly close to their goal. Then, in February 2012, when the Russians finally reached the water below, the sample obtained became immediately contaminated with drilling fluid. It would be another three years until they extracted another. 

Despite being examined in pristine laboratory conditions, the second Vostok samples suggested that even here, away from sunlight and anything even approaching a recognisable habitat, there was life – albeit exclusively microbial. They recognised some of it, too, which propagated the concern that the samples were still not contamination-free. Some of what they found down there, however, comprised a previously unidentified, unclassified bacterial phylotype named inauspiciously as w123-10 – but due to lingering contamination fears, the results remain inconclusive. 

The first sediment sample from beneath the Rutford Ice Stream.
Photograph by Paul Anker, British Antarctic Survey

Micro-barnacles and ‘water bears’

The first team to successfully access a sub-glacial lake and obtain a ‘clean’ sample was an American team in 2013, who drilled 800m into Lake Whillans beneath the Ross ice shelf and found in their extracted samples of water and sediment teeming with microbial life.  

The plot thickened on 30 December 2018 when another American drilling project – the American SALSA (Sub-Antarctic Lakes Scientific Access) expedition – succeeded in drilling through 1,000m of ice to Lake Mercer, and found something unexpected. Reported in the journal Nature earlier this year, the SALSA team discovered microscopic crustaceans, and a mud-dwelling Tardigrade – a sturdy-looking, six-legged microorganism given the nickname ‘water bear’ due to a passing resemblance to its larger, hairier namesake. Tardigrades are often referred to as the toughest creatures on earth due to their resistance to extreme environments, having been successfully revived after exposure to pressure, high temperature and even spaceflight. Why they came to be in Lake Mercer remains a mystery, but one possible explanation is that the lake received its compliment of hardy creatures due to an earlier inundation by sea water, or were deposited there from elsewhere pinned to the base of a glacier. 

The thinner ice at Lake Mercer and the coastal location may prove more amenable to life – but to find such complex organisms in the deeper, more isolated lakes beneath Antarctica such as Vostok and Ellsworth would be rather harder to explain. And while the ideas that have titillated the more imaginative about ancient sea monsters still lurking down there seem quashed, whatever is down in the dark still has to eat. The question is, what? 

Life, but not as we know it

“The only nutrients down there come from rocks,” says Keith Makinson. “There are bacteria that happily munch away on those rocks and make use of the minerals in there… so it would be a very different microbial community. It’s just a case of how different they are to the world around us and given they have been isolated for so long, and have they developed their own unique ecosystems?”

It is thought that the study of the microbial life found in the black, cold depths beneath the ice sheet of Antarctica – in pressures of up to 400 bar – may help scientists determine if life could exist in similarly harsh conditions on other planets. The logistics of Vostok remain formidable, but attention has now turned to other sub-glacial lakes which could be reached by hot water drilling. Notable is Lake Ellsworth, beneath 3,200m of ice – which a British drilling team failed to reach in 2012 when the project was called off in the early hours of Christmas Day after a technical failure. Now, with the success on Rutford and the combination of cleaner, more advanced hot water drilling the potential for exploring sub-glacial lakes over 2,600m deep and obtaining clean samples are back on the radar.  

“A lot of projects have been waiting in the wings until we’ve proved that we can drill to these depths,” says Makinson. “After the failures at Ellsworth funders were reluctant to give money to this kind of work so basically were relying on this project to prove that it’s all doable using this drilling technique.”


A magnified view of a tardigrade, also known as a water bear.
Photograph by Papilio, Alamy

A key to rising seas 

Critical to the BEAMISH expedition’s objectives was to install monitoring equipment that would allow the scientists to assess the behaviour of the ice for the future – and determine its past.

The accelerated melting of polar ice is likely to be a key factor in future sea level rise – but without reliable data to track the change and compare to an equally reliable record, it is impossible to predict with certainty the rate of any such change. In contrast to a static sheet of ice, the Rutford Ice Stream is a huge, fast flowing glacier, which is sliding over the land beneath it – and eventually into the ocean.

And the key to predicting its future? Determining how slippery it is. “The suite of sensors that we’ve put into the ice are to understand the slipperiness of the ice over the sediments beneath it,” says Makinson. “Understanding how slippery it is important for helping us to understand and predict how the ice sheet will evolve over the next century.” 

Quite a lot to learn from a very deep, very narrow and very temporary hole in a slab of ice. 



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