20131223_WS

Source: BBC World Service

URL: http://www.bbc.co.uk/programmes/p01n9gcv

Date: 23/12/2013

Event: The Return to Mawson's Antarctica - Part Two

Attribution: BBC World Service

People:

• Dr. Chris Fogwill: Glacial geologist and palaeoclimatologist
• Alok Jha: Science and environment correspondent at the Guardian
• Andrew Luck-Baker: Senior producer, BBC Radio Science Unit
• Eleanor Rainsley: Palaeoclimatologist and glacial geomorphologist
• Dr. Erik van Sebille: Physical oceanographer, UNSW
• Professor Chris Turney: Professor of Climate Change, UNSW

Alok Jha: You're listening to Discovery, from the BBC, from East Antarctica. I'm Alok Jha. I'm talking to you from the front deck of the polar research vessel the Shokalskiy, which, as you can hear, is ploughing and grinding its way through an endless maze of rafts of gleaming white ice. At the moment they're thin enough for us to steam straight through them. The ship's carrying the Australasian Antarctic Expedition 2013, a crew of Antarctic researchers and members of the public who've come along as science assistants. We're retracing the steps of the very first Australasian Antarctic Expedition, 100 years ago, and - if the conditions are on our side - repeating its studies at a place called Commonwealth Bay. The man who led that first expedition was Douglas Mawson. His words, a century ago, pretty well sum up our situation over the last couple of days.

Male actor's voice: The ice closed in, and shock after shock made the ship vibrate... followed by a crunching and grinding... The dense pack had come, and hardly a square foot of space showed amongst the blocks; smaller ones packing in between the larger, until the sea was covered with a continuous armour of ice. The ominous sound arising from thousands of faces rubbing together... spoke of a force all-powerful, in whose grip puny ships might be locked for years and the less fortunate receive their last embrace.

Alok Jha: Ooh, what's that beautiful white bird, over there?

Chris Turney: Oh God, that's well spotted - yeah, that's really close, isn't it. That's actually a snow petrel, it's one of the few bird species actually breeds in Antarctica.

Alok Jha: Joining me on deck is Co-Expedition Leader Chris Turney. Chris, this - the sight in front of us is absolutely beautiful. It's just endless, endless, endless pieces of white sea ice we're grinding through, as you can hear. But - it looks beautiful but it's not been great for our progress, so far, has it.

Chris Turney: No, no it hasn't, Alok. At some points we've made really good progress, we've moved very quickly and got south very far. And then occasionally we've just run up against one or two or three years' worth of growth of sea ice - it's just been too thick for us and we've been beaten back. And, as you know, we've been going backwards and forwards for the last 48 hours.

Alok Jha: How much of a problem was this sort of sea ice for Douglas Mawson, when he was trying to get to the Antarctic, 100 years ago?

Chris Turney: Well, sea ice is always, by its nature, been difficult for explorers, to get to the Antarctic continent. But certainly 100 years ago they were more trying to find where the continent was, and they were skirting around the edge. All the reports we have, from that amazing expedition 100 years ago, show us they were basically reaching thick pack ice one or two degrees actually further south from where we are at the moment.

Alok Jha: So have we just been unlucky, then, in terms of reaching such thick ice a bit earlier on?

Chris Turney: Well, there's certainly an element of bad luck, but, to be perfectly honest, this is part of a longer-term trend across a large part of East Antarctica, where sea ice has been actually, paradoxically expanding, over the last - recent decades.

Alok Jha: I mean, that sounds counter-intuitive, doesn't it, 'cause we hear about climate change and global warming melting Antarctica. The idea of sea ice increasing sounds quite counter-intuitive.

Chris Turney: Yeah, it's fascinating, isn't it, because ultimately, how do you explain that conundrum? One of the great ideas we're out here actually testing at the moment is the idea that a large part of the East Antarctica ice sheet is actually melting. And, of course, it's fresh water. Fresh water enters the sea water - it's less dense, so it floats to the surface and it's got a higher freezing point. So the implication is that actually, the greater sea ice extent is actually the result of ice melt, fresh water floating to the surface and then freezing.

Alok Jha: Is that a big trend throughout the whole of East Antarctica?

Chris Turney: Yes, that's right - actually it's a broader trend across the whole of the East Antarctic, you see this expanding sea ice. And, as a result, we can use our approach into Commonwealth Bay and all our scientific observations we're making as we go, as a way of testing this hypothesis, which is relevant to the broader region.

Alok Jha: How big a concern is this idea, that the East Antarctic might be melting?

Chris Turney: Well, actually 50 metres' worth of equivalent global sea level rise is actually held in the East Antarctic – it's about two and a half, three kilometres thick. So you don’t need to melt much on the edges to raise global sea levels a lot. And that's ultimately a bigger issue here, that the sign of expanding sea ice is perhaps an indication we're actually looking at greater sea level rise than predicted at the moment.

Alok Jha: We'll come back to the topic of climate change a bit later. Now, although we're many kilometres from land, we have had a chance to get off the ship and stand on solid ground - well, of sorts. We've all been out on small inflatable craft called Zodiacs, and got onto some of the floating ice floes that are surrounding the ship. Discovery producer Andrew Luck-Baker was in one party, with oceanographer Erik van Sebille.

* * *

Andrew Luck-Baker: How is this for you, Erik?

Erik van Sebille: I'm standing on the ocean! I'm standing on an ice floe, frozen seawater - this is the dream of every oceanographer, to be on the ocean and not fall through it, not get wet.

Andrew Luck-Baker: How thick do you reckon this floe is?

Erik van Sebille: Well, we're 30 centimetres above sea level, so in total there's quite a bit under sea level too, of course - two metres, two and a half metres, or so... I trust it - it looks pretty sturdy, although it does flow a little bit.

Andrew Luck-Baker: Yeah, you can sort of, quite well - you can't really feel the movement of it, or can you? Actually, I'm looking at the boat, and that's moving, so perhaps that's making me feel that this floe is moving.

Erik van Sebille: Yeah, [inaudible] one, compared to all the other floes, because this is not the only floe in the area. All the others are also moving. So it's kind of like a - it looks a bit like a jigsaw, half-finished jigsaw puzzle or so, right. There's all the pieces in there, and then there's pieces still missing.

Andrew Luck-Baker: In the distance we can still see an immense iceberg that would just be towering above this place. [?]

Erik van Sebille: It almost looks like Uluru, or so, in the middle of Australia, in the desert. And this is the white version of that, essentially. It's just enormously high, probably 40, 50 metres or so. And the thing is, it's a very different beast from the floe we're on now. This is, where we're standing on, this - just frozen ocean. That iceberg has calved, has broken off the glacier. And it's old glacier ice, it's probably ice that fell in Antarctica hundreds of thousands of years ago. It's calved off Antarctica, probably a few months to a few years ago, but when it fell in Antarctica as snow, that's a very long time ago. Because it falls somewhere in the middle of Antarctica, and then it flows along the glaciers, along the ice streams, slowly from the middle towards the edges. And once it reaches the edges it breaks off as an iceberg.

Andrew Luck-Baker: You talked about this possibly being two metres, three metres thick, this floe that we're standing on? And then, the bottom of that, it's an awful long way to the seabed, isn't it, here.

Erik van Sebille: Yes, and that's, I think, the most bizarre thing about what we're doing here, is that we are literally in the middle of the Southern Ocean. There's 3,000 metres of water beneath us. You don't even want to start thinking about the creatures that live beneath our feet at this moment, all kind of weird creatures never seen before - oh, there's a penguin over there.

Andrew Luck-Baker: Ah, yes!

Erik van Sebille: Just look at the penguin, it's coming up to us, it's looking at us - it's a small Adelie penguin. Oh, that's so beautiful.

* * *

Alok Jha: Eventually, we hit clear water, and made it to just north of Commonwealth Bay. We're about 60 kilometres from where Mawson had established his main base - that's a rocky area he named Cape Denison. We were about to come to a point where the remaining journey to reach it would have to be done on the ice.

For the past 20 or 30 miles, we've been sort of sailing through an honour guard of icebergs - huge cathedral-like things, some of them as big as small towns, probably, really neatly lined up on the horizon on both sides of the ship. And then we arrived at the edge of the fast ice, which is the ice that's stuck to the continent of Antarctica.

We're heading at quite an alarming speed, straight at the ice edge of Antarctica, there. And I'm no explorer, but even I can see that we're probably going to head straight into that thing and smash into it, so you'd better hold on. Here we go... [Crashing, booming sounds. Some laughter.] Yup, we smashed straight into Antarctica.

So we moored with a bone-jangling bang. But oceanographer Erik van Sebille was in a chilled and contemplative mood, talking to producer Andrew Luck-Baker.

* * *

Erik van Sebille: This is amazing. This is one of the best places I've ever been to. This is just... so quiet and so calm [people can be heard chattering in the background] and there's icebergs floating around, penguins - the only company we have. And whiteness, whiteness is everywhere. The amount of hues of white are just amazing - I would never have thought that there's so many different kinds of white.

Andrew Luck-Baker: Is this the first time you've been to Antarctica?

Erik van Sebille: This is my first time. And it's always been a dream, almost, right. You become an Earth scientist and you want to study the Earth. And then Antarctica has such a special place in that, it's so unique. There's so many ways that... it's a very magical moment.

Andrew Luck-Baker: Just at the extremity of the conditions here, and at the vast whiteness of the place that we've been travelling through for days - when you think about that, it actually all totally brings home to you how Antarctica is such an important part of the planetary system, if you like.

Erik van Sebille: Absolutely. Without Antarctica, our climate would be very different, particularly the climate in the Southern Hemisphere - Australia would have a totally different climate, if it wasn't for this cold snowball world down south there. But even in the North Atlantic, even in places like Europe and the US, Antarctic ice is kind of like the thermostat of our climate system. It is what controls the temperature, it is what controls the heat transfer from the Tropics to the Poles. And especially the ocean - Antarctica plays a key role, really. But the thing what's so really special and what I've been thinking about, the last few days, is that Mawson came here 100 years ago, and for him it was really exploration, it was an adventure. And even though so many things have changed since his days, it is still an adventure to get here. And that just shows how difficult this place is, how harsh conditions is - are, here. And it's a beautiful sunny day now, and I'm - I mean, I'm not even wearing gloves, and my jacket is kind of half open and... um, it doesn't even really feel like freezing. But this is a place that is both beautiful and mesmerising but also very dangerous, very treacherous.

* * *

Andrew Luck-Baker: Beautiful, dangerous and unpredictable - that's Antarctica. You're with the BBC, on the Australian [sic] Antarctic Expedition. But not, for the time being, with Alok Jha. This is Andrew Luck-Baker instead, because, as I speak, Alok is in fact now in Mawson's hut, the main base of the original expedition a century ago. Things change by the hour here, and in the last 36 hours, the decision was made for two small parties to go the 60 kilometres across the sea ice into Cape Denison. Only a handful could go. Alok was one of the chosen few. You'll hear what happened and his experiences in a later programme. Anyway, now Chris Turney was in the first party, and he's back, he's here right with me. Chris, it was 24 hours non-stop for you, wasn't it.

Chris Turney: Oh, it was an incredible adrenaline rush, Andrew. We set out about 6:30 yesterday morning, basically had to carve out a route across the sea ice, following approximately where we knew Cape Denison to be. And then finally, after about three hours' worth of driving these all-terrain vehicles across, we suddenly saw this patch of rock in the far horizon. And that was Cape Denison, and suddenly I though "Gosh, we're going to make it". [Laughs.]

Andrew Luck-Baker: And the hut? Mawson's hut? What was it like, to go in there?

Chris Turney: It was so weird to actually turn up there, at last. We stepped into this incredible time capsule - I mean it was just amazing! This is a place where all those iconic photos - you see these men who stayed there for two years. And that tiny space, you know, you see the photos and you think "My gosh, it must have been enormous". [?] And you realise the photos must have been taken by - on almost the same point, swivelling around, taking these different shots - incredible.

Andrew Luck-Baker: Absolutely remarkable. But on the other hand, on the science side, just give us a brief account of how much got done.

Chris Turney: We had to hit the ground running, as soon as we arrived, so one team went off straight away and looked at the former limits of the ice sheet, collecting geological samples. We went round taking photographs of some of the bird colonies. We also had to look at the automatic weather station that hasn't worked for two years. So all these pieces of work had to be done in an incredibly short period of time. Basically, we had about 12 hours on the site and we got huge amounts done, and hopefully the team are in there now, finishing off the next bit.

Andrew Luck-Baker: Now, this is a very British question. It's about the weather. [Chris Turney laughs.] How windy was it? Because this place is supposed to be the windiest place on Earth, Cape Denison.

Chris Turney: That's right. It's meant to have average wind speeds of 70 kilometres an hour, and I'm actually slightly embarrassed to say it was absolutely calm and still! But yes, it can get incredibly windy there - we lucked out massively, we turned up on a perfect day for doing work.

Andrew Luck-Baker: Douglas Mawson certainly experienced windy conditions down there. He actually named it - this place - "The Land of the Blizzard", and we can hear, in his own words now, a description of the winter blizzard conditions.

Male actor's voice: A plunge into the writhing storm-whirl stamps upon the senses an indelible and awful impression seldom equalled in the whole gamut of natural experience. The world a void, grisly, fierce and appalling. We stumble and struggle through the Stygian gloom; the merciless blast - an incubus of vengeance - stabs, buffets and freezes; the stinging drift blinds and chokes.

* * *

Andrew Luck-Baker: Now, along with Alok, as we've just heard, some of the scientists got into Cape Denison to repeat studies and measurements Mawson's team did 100 years ago. Now, the big idea here is to try to see how things have changed in this part of Antarctica in the last century, particularly with climate change in mind. One of the team to go in was glaciologist Eleanor Rainsley - her focus is the past and the future of the colossal East Antarctica ice sheet, its outer edge I can see gleaming and rising at the horizon. Eleanor told Alok about the ice sheet, in Discovery's creaky ship's cabin studio, before they both went to the cape.

* * *

Eleanor Rainsley: It's an ice sheet that's traditionally been thought to be very stable - it's this massive ice sheet we've got in the world, locking up all this fresh water. Obviously, if that melts we're all going to under water and it will be disastrous, but at the moment, it's pretty stable. And we've got all these receding glaciers in the world, but the East Antarctic, for the main part, is staying put. However, there's been a few studies recently, have suggested: actually, it's more vulnerable than we think. So what I'm trying to do is reconstruct the history of this particular part of the East Antarctic ice sheet, and see how it's fluctuated in the past.

Alok Jha: So what's the state of the East Antarctic ice sheet right now - how big is it? How much ice is locked up in there?

Eleanor Rainsley: Australia could fit into it, easily. There's 53 metres of sea level equivalent in there - that means, if that was to melt tomorrow, the sea level over the entire world would raise [sic] by 53 metres, and every city in the world, pretty much, would be gone. So, at the moment, the East Antarctic ice sheet's looking good, but... It's a big worry, that these things could change.

Alok Jha: So tell me what experiments you'll be doing, to reconstruct the history of this place?

Eleanor Rainsley: So, Commonwealth Bay here offers a mass of opportunity for us, because this area of the East Antarctic ice sheet is basically all ice. There's very little land, and that's why we don't really understand what's happened to it in the past and what might happen to it in the future. Cape Denison and Commonwealth Bay offers this tiny little nugget of land, about two kilometres wide, but it could offer us this vast wealth of information about what happened in the past. So I'm going to be collecting lots of different samples. And, most disgustingly of all, chiselling away at deposits of snowy petrel stomach-oil deposits - they've built up over time - and then radio carbon-dating them to work out how long since this area's been ice-free.

Alok Jha: And why is it important to know about the history of this area? What is it you're trying to answer, in the bigger scheme of things?

Eleanor Rainsley: The big picture of looking at the East Antarctic, and trying to reconstruct its history, is because about the only we know of what's happening in the future of our world is these ice-sheet models, these - and these climate models, these computer models that are put together by people far cleverer than me, with their big equations. But unfortunately, anything you make in a computer is always going to be a simplification of the real world. And we've got no real way of knowing whether these predictions that we're making are right. We make all these big predictions about 0.5 metres of sea level rise by the end of the century, but unless we can actually truth [?] these models in some way, we don't know if these predictions are accurate.

So what we do is, by reconstructing what's happened in the past, happened to ice sheets in the past, with past climate changes and past fluctuations in temperature, we can then look and see: well, can these models predict what happened in the past, accurately? Or can we even build these - this data we get from the field - into the models, to make sure they're more accurate, help them to predict global climate.

* * *

Andrew Luck-Baker: Eleanor Rainsley. Chris, I'd like to bring to focus back into this area, specifically, of East Antarctica. Something dramatic, of enormous proportions happened here a few years ago, didn't it, namely that huge iceberg we can see looming between here and Cape Denison. What happened? What's it doing there?

Chris Turney: "Berg" almost doesn't do it justice, does it, really. It's almost as far as the eye can see. It's over 100 kilometres long, and it originated as a larger berg in the Ross Sea, which is to the east of us. And over several years it's been migrating westward. And three years ago it turned up on the edge of Commonwealth Bay, and in an Antarctic version of billiards, it knocked the edge of the Mertz Glacier - which was extending out into the sea - off and disconnected it. And that's disrupted the ocean circulation in the region massively, so much so that when you get these strong winds it's very hard for it to flush the sea ice that's in the area away.

Andrew Luck-Baker: And it extends all the way out here to where we are -

Chris Turney: That's right.

Andrew Luck-Baker: - about 60 kilometres.

Chris Turney: That's exactly it, that's right. And of course that's completely separate to this far more extensive sea ice that we've spent so long trying to get through, to get to this point.

Andrew Luck-Baker: Thanks, Chris. Now, this vast marooned iceberg, and the effect it's had, and the great expansion of sea ice around East Antarctica generally - Chris talked about that, earlier - may be having impacts way beyond this part of the world, possibly as far as the Northern Hemisphere. Now, these events might be disabling one of the, kind of, cylinders of the global heat engine which moves ocean waters, and with them warmth and cold, around the planet. This is something Expedition Co-Leader Chris Fogwill and oceanographer Erik van Sebille are investigating...

* * *

Erik van Sebille: If you just tag a litre of water, or something, and follow it for thousands of years around the ocean, then what you would see is that it would basically do a roller-coaster ride. It would go around to different basins and it would go up somewhere, near the Equator probably, and sit at the surface for a time, and then sink somewhere. And there's two or three main sites where that sinking happens. It happens near Greenland, in the North Atlantic, and it happens around Antarctica. It happens in the Weddell Sea and in the Ross Seas - on both sides of the Antarctic Peninsula - and in Commonwealth Bay. So, where we are now is a very important site for the sinking of water. Now, water here gets cooled so much by the winds overlying it, so the winds extract all the heat and the water gets to minus 1.6, minus 1.7 degrees Celsius. And because it's also relatively salty it sinks, so it might sink all the way to 4-5,000 metre depth.

Chris Fogwill: Since the arrival of this big iceberg, the bay's completely changed its circulation, and also its surface. So before, it was largely open water, when people would come here in the summer, and you could take a ship right into Mawson's Hut. But since the iceberg's become grounded, just off the bay, the whole bay's become packed in with what we call "fast ice". It's attached to the land, and it builds up annually, so it gets thicker and thicker - at the moment, our best estimate is the ice underneath us is 3-4 metres thick, but we're going to have to drill through this to look at the water under the sea ice and get to see if that's warming or freshening or changing in its properties. The sea ice is providing us with this amazing platform to undertake a unique experiment.

Erik van Sebille: What we are interested in is to find out, at this point, what happened with the water beneath that. It has always been very, very cold, and always been very, very dense and plunging down to the bottom of the ocean. We think that now it can't be that cold any more, because basically the ice is acting as a blanket. The winds are still there, but they can't extract the heat from the water, they can't cool it so much, because the ice is in between there and limiting this heat exchange.

Andrew Luck-Baker: During the last couple of days, Erik's been out at several key spots on the expanse of fast ice, with a coring drill and a gang of science volunteers, to make measurements.

[Sounds of crunching footsteps.]

Erik van Sebille: We are right in the process of getting this deep core - the ice is probably some 3, 4 metres deep here, we're now maybe one and a half metres in, so we still have quite some work to do. It's all manual labour - that's in the spirit of Mawson, But, as we drill the hole, we get into the sea below the ice, 4 metre down, where we are now, there will be all this water. And then what we're going to do is we're going to launch a temperature probe through that. It looks a little bit like a grenade, and it can measure both temperature and salinity, as it goes all the way through the ocean. And what we really hope then is to see the changes between what Mawson measured and what we are now here. So what has climate change done to the water in this bay? What has the ice cover done to this water in this bay?

Chris Fogwill: After the arrival of this big iceberg, B09B, a science group came down here and they discovered that there was a slight freshening of the ocean. Now it seems like something in that system is out of kilter. No-one's been able to get back to retake those measurements, so for us it's a unique opportunity to try - and if it is freshening, then that's a real sign of worry. Because it means that the processes of Antarctic bottom-water formation aren't going on, and if you don't keep that thermohaline circulation system going, keep this system of cold, salty water produced to go into the world's oceans, it could have substantial knock-on effects for the circulation systems of the global oceans.

Erik van Sebille: If indeed this formation of bottom water has ceased all around the eastern side of Antarctica, then that will then impact all of the other currents, to the sinking of water near Greenland even, in a few decades, probably, because all the currents are reacting on each other, so one stops, the others might change, too. In the North Atlantic, near the East Coast of the US, and Europe, they play an important role in bringing heat towards the Poles.

Andrew Luck-Baker: So the idea is that the Southern Ocean around Antarctica, if the currents there slow down, then as far away as Northern Europe, you'll get maybe a cooling, because the Gulf Stream and other things also slow down.

Chris Fogwill: Yes, yes. This is completely tied into global climate. We've got to get away from saying Antarctica's isolated, it's out of the way and it doesn't matter to us. The real key message is: things that are going on down here, right now, are absolutely tied to the rest of the world.

* * *

Andrew Luck-Baker: Well, that's almost it for Discovery this time, except for some hot-off-the-press findings from the very seawater experiments that we've just heard about. I'm in the expedition ship lab with Erik. Erik, you've been analysing the data just in the last few hours. Very briefly, what have you found and what does it mean?

Erik van Sebille: What we've found is that since Mawson was here, the seawater has become much fresher. The upper 50 metres, the seawater is so fresh that you would actually be able to taste the difference. It's so much fresher, and just because of the sea ice on top.

So the sea ice we see all around us, suddenly it changes the ocean circulation.

Andrew Luck-Baker: So could this mean that Commonwealth Bay - at least this key part of the planet's ocean water heat engine - isn't working any more?

Erik van Sebille: Here, at least, this deep water formation has just shut down. And all the water is too fresh to sink to the bottom of the ocean.

Andrew Luck-Baker: Thank you very much indeed. And that has to be it, I'm afraid. You've been listening to Discovery, with the Australasian Antarctic Expedition in 2013. Join us next time for more science and adventure from the BBC World Service in Antarctica.