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Antarctica’s Deep Bore Ice Cores

Antarctica. A vast, frozen land that sprawls for 14 million sq km (5.4 million sq miles) – which is bigger than Canada and India combined – and with an ice sheet that measures 4.7 km (2.9 miles) in thickness at its deepest point. The first human sighting of the great white continent came almost exactly two hundred years ago in 1820 and it is an area that has drawn explorers and scientists ever since. But despite this, much of Antarctica remains unexplored and untouched – perhaps no more so, than what lies beneath our feet. 

The European Project for Ice Coring in Antarctica (EPICA) has been drilling in Antarctica for over two decades now – their prize isn’t oil or any kind of mineral but rather pieces of ice that are hundreds of thousands of years old. By studying this ice it’s hoped that we might be able to better understand the changes that our planet has seen over time, which in turn may help us to predict the effects of climate change more accurately.   

Their recent findings have opened up a window to the past that stretches back an extraordinary 800,000 years, but with new ice cores planned, the group hopes to push our knowledge back past the 1 million year mark. 

These are megaprojects in the truest sense of the word. They involve painstaking processes that can take years to complete in temperatures that are at best -22 C (-7.6F). This is not glamorous work and it receives far less attention than it really should. But the data coming out of these ice cores is staggering and has enabled us to map out our planet’s past like never before.  

Ice Cores

Before we look at the history and build-up to the current ice cores, it’s probably worth explaining a little about the cores themselves. 

An ice core is essentially just a block of ice, but a piece of ice typically taken from deep down inside a glacier or an ice sheet. The blocks are then be analysed to discover a wide variety of factors, such as natural climate change across glacial cycles, temperature, precipitation, wind strength and composition including different minerals and gases which can be compiled to give a clear idea of what this part of the world might have looked like hundreds of thousands of years ago. 

Ice cores are excavated using specially designed ice drills, which work their way down then cut a cylindrical shape out of the ice that is then brought up to the surface. 

Early ice drills were known as hand augers, a design patented in 1932 which remains remarkably similar even to this day. An auger is a cylinder with helical metal ribs (known as fights to those in the industry) located on the sides, which cut into the ice. Traditional augers were positioned on the ice then slowly turned by hand and so pushed them down. When the process was reversed, the auger would twist out of the ice bringing with it a nicely cut potion of frozen history. 

Nowadays, using tripods and mechanical versions of the auger, scientists can go as deep as 50 metres (164ft) in a single sitting (though 30 metres (98.4ft) is considered close to optimal because of the stress on the drill). Some modern ice cores are now dug with a string of drill pipes which can be incrementally added to as the pipe descends into the hole while cooling liquid is pumped down to cool the surprisingly high temperature that the drill can produce even in thick ice.  

Once the ice is removed from the holes it is sometimes studied on-site or shipped immediately to an ice core storage. Researchers from around the world can then apply to study pieces of ice from certain areas and particular periods.    

History

People have been drilling ice cores as far back as the mid-19th Century. A Swiss-born American biologist and geologist by the name of Louis Agassiz drilled holes in the Alps in 1841 and 1842 but did not remove any cores. During an Antarctic expedition in 1902 and 1903, a series of 30 metres (98.4ft) deep holes were drilled with scientists taking temperature readings from the bottom of the holes.

The process of sampling took a huge step forward with the work of James E Church and his drill design that was able to retrieve ice cores for the first time. Over the winter of 1908 and 1909, he constructed a steel tube complete with slots and cutting heads that could bring up cores measuring up to 3 metres (9.8ft) in length.   

The first major study of snow and the ice beneath it came in 1930-31 with the Alfred Wegener Expedition to Central Greenland. The ice cores were the responsibility of Ernst Sorge who dug a 15 metre (49ft) hole and carefully examined the layers that were brought up. These findings went on to underscore Sorge’s Law of Densification – a series of mathematical equations that are used to measure how quickly snow accumulates and compacts. 

The 1950s saw a large increase in the number of ice cores, with studies getting underway in Alaska, Greenland and Antarctica. The International Geophysical Year (IGY) – a global scientific project involving 67 countries – was held across 1957 and 1958 with deep cores emerging as one of the high-priority research targets. A 307 metre (1,007ft) core was drilled at Byrd Station in Antarctica, while in Greenland drills descended to a record depth at the time of 411 metres (1,348ft). 

The success of the IGY meant an uptick in both the interest in ice core drilling and also the technology to do it. In 1966, a hole drilled by the American Cold Regions Research and Engineering Laboratory (CRREL) reached the bottom of the ice sheet for the first time, clocking up an impressive depth of 1,387 metres (4,550ft). But that was nothing, the same drill was then moved to Byrd Station where it hit a depth 2,164 metres (7,099ft) until it was frozen in place by sub-ice meltwater and eventually abandoned. 

This being the middle of the Cold War you probably won’t be surprised to hear that there was a certain competitive quality to proceedings. The Soviet Union drilled numerous cores from the 1970s onwards with the deepest reaching 3,770 metres (12,368ft), which provided data stretching back 420,000 years covering the four previous glacial periods. In 2012, work on another ice core was stopped when it reached the surface of the ancient Lake Vostok, over 3.5 kilometres (2.1 miles) below the surface. This is the largest of Antarctica’s subglacial lakes covering an area of 12,500 km2 (4,830 sq mi).   

Before we move on, a little story about the Russian Vostok Station. Apparently in 1959 two men were playing chess when one became incensed after losing. Now, we all know people who can’t handle losing, whether it was throwing computer game controllers or taking the football home out of spite – but this was entirely more extreme. The tale goes that the man attacked his opponent with an ice axe, killing him in the process. This is a story that was denied by official Soviet channels but spread nonetheless. That murderous, evil game that is chess is now said to be banned at the Vostok Station. 

The Science

Glaciers are typically formed over thousands of years through water freezing and then slowly building up to form large areas of ice. Within this ice lies plenty of sediment, air and rock which slowly compacts together over time into millions of layers. These layers remain in chronological order and act almost as a history book – the lower you go, the further back in time you travel. 

By analysing the ice, researchers can determine a huge amount of factors. Tiny water molecules usually have an air imprint which gives scientists a fairly clear indication of the temperature at the time. The ice also contains millions of particles and by examining these small aerosols, such as dust, ash, pollen, trace elements and sea salts, it’s possible to determine major global events that occurred in the past such as volcanic activity and rising water levels.   

The ice also holds plenty of microscopic bubbles which essentially still hold the atmosphere that was present thousands of years ago. We can analyse these bubbles to give us a clear idea of the amount of carbon dioxide, methane and other gases in the atmosphere at that time. By examining large quantities of this ice, scientists can then produce accurate models which depict how climate has changed through several cycles – which I’ll explain a little more later in the video.  

EPICA  

The European Project for Ice Coring in Antarctica (EPICA), a multinational European project, has, over the last twenty-five years, retrieved some of the most comprehensive ice cores ever seen. Their work in Antarctica began in the mid-1990s and continues to this day. 

Dome C     

Members of the EPICA team began arriving at Dome C during the field season 1996/1997. This is the site of the current Concordia Research Station, operated jointly by France and Italy around 1,670 km (1,040 mi) south-east of the South Pole, but when EPICA arrived they were greeted by nothing but a wide-open expanse of white.  

Once a camp had been established, a drill casing going down 120 metres was installed close by. At this point, it’s probably worth pointing out that this is not a particularly fast process. Not only can work only be carried out during the relatively short summer months that Antarctica experiences, the drilling itself often moves at a painfully slow speed. It would take eight years until the core at Dome C reached its final depth. 

By December 1998, the drill had progressed to a depth of 781.6 metres (2,564ft) when catastrophe struck as the drill became lodged within the hole and couldn’t be retrieved. Not to be deterred, in December 2000, scientists began another hole close by and a year later had reached 1,458.2 metres (4,784ft) and 2871 metres (9,419ft) by February 2002. At this depth, the heat and effect it had on the machinery was substantial and the next field season saw only a modest change in depth. As with many things in life, the final stage was going to be the most difficult by far as the drill crawled slowly through the final 100 metres (328ft).   

On 21st December 2004, the EPICA team at Dome C reached a depth of 3,270 metres (10,728ft), just 5 metres (16.4ft) above the bedrock at the bottom. Scientists believed that the ice was melting close to the bedrock so the decision was made to halt drilling out of fear of contaminating the basal water (the bottom layer of the ice). The ice that was retrieved from this core was the oldest ice ever seen, thought to be in the region of 800,000 years old. 

Kohnen Station

Two years later in 2006, drilling ceased at another EPICA core, this time at Kohnen Station, a German-run research station located in the north of the continent. The aim here was to produce a high-resolution record of a glacial-interglacial cycle (a period that covers both an ice age and significant time without ice) in an area of Antarctica facing the Atlantic Ocean, which could then be compared with similar work going on in Greenland. The drilling was stopped at 2,774 metres (9,101ft) but still managed to record around 300,000 years worth of data.   

What have we learned?

If you look at levels of carbon dioxide, methane and temperature over thousands of years you can clearly see that the earth moves in cycles. The data points sync up so well that it’s difficult to argue that they aren’t linked, or that the earth’s cycles are self-regulating. We have a pretty good idea about the regulation because the upper and lower boundaries of the three variables are closely constrained, meaning that they usually move up and down to the same points.   

We can see how this looks over 4-8 cycles which takes us back around 800,000 years. When levels of CO2 and methane rise, so does the temperature, when they fall, so does the temperature.

Now, if you’ve long been sceptical about the idea of climate change and you think that these results show that the earth always heats up and cools down naturally, you are completely right. However – and I guess you knew this was coming – when we look at the atmospheric CO2 since 1960, it has increased by 70 parts per million (PPM). This is not a small amount, and if you look at it in the context of the eight cycles, you can clearly see that the CO2 jump is enormous and completely skews the earth’s natural cycle.

And can you guess what’s happened to the global temperature? Yes, you’ve got it, it too has jumped ship from earth’s self-regulating system and is now barrelling upwards. And surprise, surprise, it has now gone well past those normal boundaries that the earth has seen for hundreds of thousands of years.

Beyond EPICA – The Oldest Ice

In 2019 the EPICA team announced, ‘Beyond EPICA – the oldest ice’, a project that would attempt to retrieve ice dating back as far as 1.5 million years. The team arrived at ‘Little Dome C’ – 32 km (20 miles) from Dome C in late November but it wasn’t until 22nd December that drilling began. A team member described the day in the EPICA diary as “sunny – no clouds”. The following day the drill reached 73 metres (239ft) before running into problems and needing to be disassembled. 

The drill being used here is a new design known as the RADIX (Rapid Access Drilling and Ice eXtraction) and involves a downhole hydraulic motor powered by high-pressure fluid. This fluid pushes the cuttings (loose ice) to the surface between the hole wall and fluid tube. The hole was first cased, meaning a polyethene cylindrical lining was installed that went from the surface down through the snow and firn (granular snow) to the ice below. Without this, the cooling liquid would simply be absorbed by the snow. The drill itself has a 50mm diameter and a nominal speed of 10mm per second – and when I say nominal, I mean that in a very abstract sense. Work rarely proceeded at that speed for very long.    

Christmas Day was as busy as any other at the camp with the drill reaching 98 metres (321ft), while the field diary also reported significant work on the drilling tent which was under construction. Over the next few weeks, drilling progressed at an agonizingly slow pace as a series of blockages and drilling issues hampered progress.  

The season ended on 19th January 2020 with the drill at a depth of 245.7 metres (806ft). At 10 am those at Little Dome C boarded a small convoy and pulled away from the now-closed mini station. 

No doubt as Little Dome C disappeared behind them, those in the team anticipated the next season getting under way in just over 8 months. But as almost everybody on the planet can attest to, 8 months in 2020 changes everything. The 2020/2021 season has been cancelled as a result of the current situation, but it’s hoped that work will get back underway sometime in November or December in 2021. 

The oldest ice we have ever seen and the clues it may hold will have to wait – for now.  

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