The World’s Biggest Iceberg

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Hello, lovely, curious-minded people, and welcome to Inside Science, an audio exploration of the scientific discoveries and developments that are shaping our world.

I'm Victoria Gill.

And as science stories go, it does not get much bigger than a trillion-tonne iceberg.

We will be finding out exactly where the colossal mega berg A23A is, where it's headed, and what that means for thousands of penguins and a few scientists that are in its path.

We're also asking, how do you dispose of the world's largest stockpile of radioactive plutonium?

And we have a special guest to guide us through the highlights of this week's science news.

And that guest is fellow radio presenter and fellow nerd Caroline Steele, who joins me now.

Hi, Caroline.

How are you doing?

Hi, I'm good.

Thank you for having me on.

It's an absolute pleasure.

Give us a little teaser.

What do you have for us today?

Okay, so I've got the results of the very first study looking at whether or not banning phones in schools works, a good reason to scratch a niche and the perfect way to boil an egg.

That's quite the smorgasbord.

Looking forward to talking to you later.

We'll be back with you throughout the programme.

First, though, back in December, the world's largest and oldest iceberg broke free from Antarctica after being trapped close to the continent for more than 30 years.

This berg is a behemoth, a trillion tons and more than 1,400 square miles.

It's now on a slow journey northward and worryingly could be on a collision course with the island of South Georgia and its millions of seabirds.

One of the many scientists tracking the iceberg's ominous journey is Andrew Myers from the British Antarctic Survey, who joins me now.

Hello, Andrew.

Hello.

Great to be here.

It's great to have you.

Thank you for joining us.

You are one of very few people who've actually seen this colossal iceberg firsthand.

How did you get so close to it?

How close were you?

What was that like?

It was actually a really fortuitous accident, really.

I was leading a science expedition on the ship, the Sir David Attenborough, and the iceberg actually happened to be in our path, and our planned path sort of lay over top of it.

So we actually had to go around it.

And it was an amazing sight to see.

Around it.

What was that like?

I mean, when you talk about around it, the size of this thing, how long does that take?

What's it like actually seeing it in real life?

It took us almost a full day to steam past it, going at a reasonable pace.

And seeing it in real life, it sort of loomed, seeing it appear out of the mist was really phenomenal.

It looks like a huge ice cliff stretching from one horizon to the other, just reaching out of the ocean and towering above the ship.

How high are those sides?

When we saw it they're about 40 meters.

The iceberg has shrunk a little bit but it should still be of the order of 30 or 40 meters.

And so much of it underneath the surface as well.

Where is A23A come from?

So all icebergs begin, or Antarctic icebergs, begin their life as part of the Antarctic ice sheet.

So you can think of the Antarctic ice sheet as something of a dome sitting on the land.

And as it oozes its way slowly off the side of the continent, eventually it reaches the ocean.

And ice being ice, it will float.

and then it will float out several hundred kilometers into the ocean.

And eventually when it stretches out far enough, the processes of tides and waves and basal melt eventually snap off chunks of these as icebergs.

And so why didn't this one float away when it broke free?

Because that was about 40 years ago nearly.

It was.

It's almost the same age as me actually.

It broke loose, but because it's so deep, as you mentioned, it stretches a long way underwater, up to three or four hundred meters in places.

It sort of drifted a little distance, but then ran into some shallower bottom and basically grounded and became stuck.

And it stayed there until 2020, when enough had melted that it floated loose.

And then it took still another three years to very slowly make its way out of the Weddell Sea, which is very clogged and thick with sea ice.

It actually followed the path of Shackleton's endurance before it was crushed.

Oh, wow.

That's interesting.

So, is that kind of melting and breaking free of this particular iceberg a result of warming temperatures, of climate change?

Is that linked to the conditions change in the Antarctic?

So any individual event you can't really put down to climate change.

It is completely natural that icebergs break off the Antarctic continent and even very large ones like this.

What we can say though, however, is that the rate at which ice is lost from the ice shelves has increased.

So over the last 20 years, we've seen a deficit of around 6 trillion tonnes in iceberg carving.

So that much has broken off and not been replaced by the ice coming from behind.

And roughly a similar amount has actually increased in melt.

So we've lost about 12 trillion tonnes worth of ice shelf in 20 years.

And that, we do believe, is due to climate change.

Right.

So on A23A, can you tell us about its journey?

Because it didn't get that far before it got stuck again.

And now it's heading northward.

What's its journey been so far?

Right.

So as I mentioned, it took about three years to get out of the Weddell Sea.

And then it actually came out into the Antarctic Southern Ocean proper.

And over 2024, though, it actually got stuck in a little little interesting oceanographic phenomenon called a Taylor column, which is a sort of a spinning circle of water that appears over subterranean mountains and sort of sat there spinning for about seven or eight months before in December last year it started heading north and picked up the very strong circumpolar current or at least one of the jets within it and that's taking it towards South Georgia.

And on that note, we've heard from someone who knows South Georgia very well.

Mark Belsha is a marine ecologist and director of fisheries and environment for South Georgia.

So earlier we asked Mark what is this incredibly remote island like and what impact could the giant iceberg have if it gets there?

It is stunningly beautiful.

Huge glaciers flowing into very fjord-like scenery.

The green fringes of the island form this fantastic habitat.

in which penguins and seals in particular can haul out and use as their breeding grounds.

This iceberg, A23A, is vast.

It's moving very, very slowly, just at a couple of knots.

Located to the southeast, about 170 miles to the south, South Georgia has a wide continental shelf surrounding it.

So the iceberg is likely to end up grounded probably 50 to 60 miles from the island itself.

And it's when the ice tends to break up that it becomes certainly more of a hazard for navigation.

And unlike further south, where historically Emperor penguins have been impacted by the ability to reach their feeding grounds at South Georgia that's unlikely to happen and penguins and seals will just forage in different areas where there isn't ice.

Icebergs, once they become grounded, will still continue moving very slowly and will be able to churn up sediment.

It's a process known as iceberg scour.

But this is something that's presumably been going on for millennia.

Speaking to colleagues at the British Antarctic Survey, I think there is concern that if the frequency of these iceberg events increases, then perhaps the ability for organisms to respond and recover might be changed.

But I don't think we have any real concerns, given that this is an area where icebergs and the effects of what happens after they break up occurs very, very regularly.

Thank you to Mark Belshier there.

Fascinating.

I so want to go to South Georgia.

It sounds utterly incredible.

Andrew, Mark mentioned iceberg scour there.

What is that?

Yeah, so that's the process by which when an iceberg grounds, so at the bottom of the the iceberg touches the bottom of the ocean, it will dig up a lot of the sediments and actually scour it into the rocks.

And that process kicks up all these nutrients, and particularly things like iron, which are traditionally quite hard to find in the surface of the ocean, but actually are a very important part of the food chain.

So you can actually stimulate phytoplankton blooms, which in turn feeds krill, which in turn can actually provide food for a lot of the really interesting creatures that we see around the southern ocean, like penguins and seals and whales.

So they have these icebergs have such a dynamic effect on the ocean ecosystem and on kind of the physical shape of the seabed.

This one being so big, what other impacts could there be?

Because it is so deep, it actually reaches down from the surface layer where most things actually live into the deeper layers of the ocean where there are a lot of nutrients.

But because there's no light, the creatures can't utilize these.

So it is so deep, it actually breaks through this mixed layer and starts stirring up this deep nutrient-rich water.

And also, as it melts, it can drop iron itself because as mentioned before, it has scoured its way down the Antarctic continent.

So it's actually sort of impregnated in areas with iron.

So yes, even without hitting the bottom, it can actually provide a real incentive to blooms.

And it's a really interesting sort of natural laboratory for us to study.

So, and there's a lot of research going on into A23A.

What else can we learn from it?

What else are scientists like yourself trying to understand?

So when we encountered it fortuitously, we took lots of photos, of course, but we also undertook a lot of opportunistic sampling.

So we were basically measuring its changes to the physical properties of the surface of the ocean.

As it melts, it drops fresh water into the ocean, which changes the ocean stability.

We were measuring the nutrients I mentioned and basically looking at the composition of the phytoplankton in the region.

So we were studying how it's affecting its immediate environment.

Previous large icebergs like this, we've driven actually robot gliders.

It's a bit dangerous getting people onto or around icebergs, particularly close, but we can fly these gliders around and underneath, which allowed us to study again how it's changing the environment around it.

So while we don't have studies going on with A23A right now, we do really find these interesting examples of the wider southern ocean processes that we like to study.

Right, right.

So lots more to investigate there.

Can we talk about A23A's name?

I wonder where that name comes from.

It doesn't seem quite as kind of colossal as an inspiring as I feel it might be.

No, it is.

It's a little bit boring and a bit scientific, I'm afraid.

It's sort of like these very boring names you get for stars, which are just a list of numbers and letters.

The A refers to which area around Antarctica it came from.

So this came from the Weddell Sea, and for whatever reason, that is an A, not a W.

23 refers to that's the 23rd such iceberg beyond a certain size.

I think it's about 20 nautical miles long or 10 nautical miles, so big enough to be tracked by satellites.

And A refers to the fact it used to be a bigger berg that actually broke, and this is the largest of the fragments that came from that A23 original.

Okay, very sensible, but I think you know, I think maybe we can do better for an iceberg that is quite so big.

We have some suggestions from the Inside Science team.

Can I put them to you to put to the British Antarctic Survey?

I don't know whether they have any sway in this.

We do have a naming board, it's usually for places, but I'm sure they'd like to listen to suggestions for icebergs.

Okay, so my first one is Sir Ernest Burgleton.

Yep.

Just any thoughts on that?

Was like tumbleweed?

It's on the same journey, a bit of historical context.

To the the naming uh naming uh debacle we had around our uh our research ship today

which was it was wonderful it was

it was a wonderful debacle on on that subject icy mcberg face oh yes uh yeah it's tradition now i guess

i don't know do you do you have any thoughts were you pushing for it to be named after you it's almost exactly your age isn't it so uh it is almost my age yeah so i i think i'll put that to the naming committee though given it's likely to break up in the next few months i i'm not sure if that's really a great aspiration

I'll vote for Andrew Iceberg since you were kind enough to give us so much insight for this absolutely fascinating discussion about this colossal iceberg on inside science.

Andrew Myers, thank you so much.

Thank you.

It's been a pleasure.

Now, Caroline Steele, you are here to bring us your science pics of the week later on, but have you been following the movements of this megaberg?

I have.

I've been watching them closely.

And actually, I've come across an interesting story related to A23A.

So back in 1986, Russian scientists on Antarctica noticed that one of their research stations had just disappeared.

Wow, okay.

And I had a look at some old news articles from the time, and it's interesting, sort of, journalists speculating what might be going on.

Quite a few thinking, you know, maybe it's drifted off on an iceberg.

But it took a while to find this research station.

And of course, eventually it was found on A23A.

Really?

Yeah.

And so, and what happened?

So Russian scientists quickly sent emergency boats to go and get all this expensive equipment.

Luckily, there weren't any people on this research station at the time, but there was lots of expensive kits.

So they sent out several boats being like, oh, no, this is going to drift off into the ocean to be never seen again.

But of course, really, yeah, so there wasn't really a rush because it ground to a halt quite close to the shore for decades.

So they could have, you know, really taken their time.

But they got everything back.

But they did get everything back, yes.

And it all got moved over to another research station.

So good story in the end.

Extraordinary.

Thank you so much, Caroline.

More from you later.

Now, from a giant iceberg to a giant pile of highly radioactive material.

Last week, the government announced rather quietly that they are going to dispose of the UK's huge stockpile of plutonium.

Nuclear waste specialist Claire Corkhill explains all.

If you close your eyes and think of radioactive waste, just for a second, I bet you're imagining a barrel oozing and overflowing with a glowing green goo.

Disappointingly, it's much more boring than that.

It doesn't glow and it isn't even goo.

Well, most of the time.

In fact, radioactive waste comes in all sorts of flavours, from scraps of metal to chunks of cement.

But it's plutonium, a rather boring-looking grey radioactive powder, the sort that powers DeLorean time machines, that's got us nuclear pundits talking this week.

And specifically, the world's largest stockpile of this feared and hazardous material, right here in the UK.

But what's it doing here?

Where did it come from?

The first nuclear reactors in the world were built in the UK in the 1940s and 50s and designed to generate plutonium for atomic bombs.

By changing the fundamental nature of uranium atoms inside a reactor, lots of plutonium was made.

But plutonium is also created in tiny amounts as a byproduct of regular nuclear power, the type that generates electricity for our homes through the splitting of uranium atoms.

Through a recycling process, plutonium is extracted from the nuclear fuel because it can be used to generate electricity too.

Space rovers and satellites have been powered by plutonium batteries, including one that went to its namesake celestial body, Pluto.

When nuclear fuel recycling started in the 1960s, there were futuristic nuclear reactors planned that could have used plutonium as fuel.

But 60 years of recycling and some 140 tonnes of plutonium stockpiled later, these reactors haven't materialised.

So no one is using this giant glut of plutonium.

And now it's being stored in specially designed, high-security warehouses at the Sellerfield site in Cumbria, complete with armed guards to prevent it from getting into the wrong hands.

Since it won't be used as fuel, and the costs of keeping this plutonium secure are astronomically high, more than £70 million a year, the UK government has just announced that they will dispose of it.

But how exactly do you get rid of tonnes and tonnes of highly dangerous material?

Here's what's going to happen.

It's going to be turned into a radioactive rock-like substance, packaged into containers and placed in specially engineered vaults over 500 meters deep underground in a giant landfill or a geological disposal facility.

And in this facility, alongside all of the UK's other radioactive waste, about enough to fill Wembley Stadium, it will be entombed for the hundreds of thousands of years it will take for the radioactivity to reduce to levels safe for people of our future civilisations to be around.

It doesn't sound straightforward, does it?

But these plutonium rocks, or waste forms to give them their proper name, are easier to make than you might think.

The process is a bit like baking a cake, albeit a very unpalatable radioactive one.

The plutonium, as a powder, will be mixed with other chemicals and shaped into cylinders, a bit like a dry cake mix in a round baking tin.

Then it will be baked at a very high temperature and transformed into a very dense, solid, hard and durable rock-like material that will lock up or immobilise the plutonium.

How do we know these plutonium rocks will be safe for hundreds of millennia in their underground tomb?

Studying ancient natural uranium-containing minerals has given scientists some clues.

Uranium is very similar to plutonium and is found in minerals like uraninite, pyrochlor and zirconolite.

These have been shown to retain almost all of their uranium despite having been squished under mountains and exposed to the sort of hot volcano-induced fluids that are capable of dissolving many other types of hardy rocks.

And these uranium-containing minerals are over one billion years old.

That's about a quarter of the Earth's age.

So nature, and more specifically mineralogy, has provided scientists with the answer, or rather the recipe to keep the cake analogy.

We know how to dispose of 140 tonnes of plutonium.

Now we just need to crack on and bake that cake.

Thank you to Claire Corkhill, who is Professor of Radioactive Waste Management at the University of Bristol.

Science watcher Caroline Steele is here with me.

And Caroline, before we ask for your pics of science news this week, there was an announcement about nuclear power in the UK today about smaller nuclear nuclear reactors.

Yeah, so the government has just announced plans to make it easier to build smaller sort of mini nuclear power stations in England and Wales, which is interesting because nuclear power provides about 15% of the UK's electricity at this time, but a lot of our old reactors are due to be sort of decommissioned and retired in the next 10 years.

So this could sort of fill that gap.

More nuclear reactors means more nuclear waste in the long term.

That's something that we've been following a little bit on this programme.

It'll definitely be one to watch.

But Caroline, we have chatted through megabergs, radioactive waste, but we asked you to trawl through the many journal papers and interesting stories this week and bring us your need to know science of the week.

So what have you got for us first?

So my first story is about phones in schools.

So I've got a question for you.

How long do you think secondary school students spend on their phones on average every day?

What would your guess be?

Good.

That's, wow, in a whole day or in a school day?

In a whole day, including the school day?

I'm going to go

four hours.

Yeah, four to six hours.

Wow.

Which is a lot of time.

I mean, to be honest, I spend a similar amount of time on my phone, but I was going to say.

Yeah.

Not when I was in secondary school.

It feels like a huge fraction of the day, especially because spending too much time on phones has been linked to lower grades and worse mental health.

So there's been a lot of discussion in the news about whether or not phones should be banned in schools.

Some schools have banned phones, some haven't, some are considering it.

But until now, there hasn't been any research looking at whether or not these bans work in a sort of direct way.

But there is now some research.

So researchers at the University of Birmingham published a paper in The Lancet where they looked at over 1,200 students in 30 schools.

Some of the schools had phone bans and others didn't.

And so now we've got the results.

We've got the answer to the question, do phone bans work?

What do you think?

I mean,

I would have assumed yes.

What did they find?

So I was really surprised by this.

So banning phones in schools is not linked to pupils getting higher grades or having better mental health.

So just no measurable positive impacts on students' performance, on students' mental health at all?

No, and they also looked at differences in sleep, classroom behaviour, and exercise.

And I also found this bit really, really interesting.

So although banning phones in school obviously reduced how much students were on their phones during school hours, it actually didn't affect overall phone use.

So the scientific studies do not back up the calls for, and there have been a lot of calls for bans on mobile phones in school.

So the study called for a sort of more holistic approach to lowering phone use.

And I think this is one of those subjects that everyone feels quite strongly about and has strong opinions on.

But I think it's exciting that we've got some actual science here, some actual data.

And I think it's important to pay attention to what future research shows us.

Yeah, bringing some evidence to this.

It's a complicated debate.

Yeah.

Thank you.

So

we've got a slightly different subject to move on to, a more physical study.

What have you got for us next, Caroline?

So this one's about itching.

And I apologise in advance for probably making you feel itchy because we all have that experience, don't we?

We feel itchy, we scratch and itch.

I'm so allergic to mosquitoes.

It gives me sort of horrible flashbacks of particularly mosquito-bitten holidays.

Yeah, and you know, even though you know if you don't itch that mosquito bite, it will go away,

you still want to itch it, right?

Irresistible.

Yeah.

So scientists think, you know, maybe because it feels good, it's irresistible, there might be some evolutionary benefit to scratching an itch or itching a scratch.

There's sort of one classical explanation for it, which is that scratching or itching might sort of of brush off a pest or parasite that's causing the itching.

But people sort of think that's not the whole picture because often, like with a mosquito bite, the mosquito's gone by the time that area feels itchy, right?

So scientists at the University of Pittsburgh in the US have done an experiment to try and find out more what's happening when we scratch an itch.

And they've just published their results in the journal Science.

So the way they did this, I think, is really interesting.

They made mouse ears itchy.

How did they do that?

So they literally rubbed some itchy stuff on mouse ears.

I think it's a related compound to poison ivy.

So they did that on half the mice and not on the other half of the mice.

And on half of the mice, they put sort of dog collars, you know, those cones of shame that dogs might wear after.

Ah, yes, I'm familiar.

Seemed to be very, very small ones.

Very, very small ones, yeah, so that they couldn't reach their ears to scratch them.

And the mice that were able to scratch their itches had redder, more inflamed ears with more neutrophils, which is a type of immune cell.

Right.

So the familiar don't scratch it, it'll get worse

effect.

But they also found that mice that were able to itch their ears were less likely to have the dangerous skin bacterium, let's see if I can say it right, Staphylococcus aureus, which is commonly part of skin infections.

Ah, okay.

So there's a protective effect as well, and that's the kind of explanation behind the itch paradox.

Yes, it might be part of the story, right?

So, it looks like itching an itch has some kind of antibacterial effect.

Fascinating.

And poor itchy mice.

Poor itchy mice.

But sadly, scientists are saying it's not licensed to sort of scratch every itch because apparently, overall, it's still likely to do more harm than good.

Frustrating, but expected.

So, moving quickly on from itchiness, I hear you've been boiling eggs in the name of science, Caroline.

Yes, I boiled an egg last night in the name of science.

Are you any good at boiling eggs?

I'm, do you know, not brilliant at boiling.

I feel like my singular culinary talent is poaching.

Ooh, fancy.

But I do love a boiled egg, so I'm excited to hear about this.

Well, you'll be relieved to hear that you're going to get really good at boiling an egg because engineers have found the perfect solution.

I don't believe it.

How so?

Well, the difficult thing about cooking eggs is that the white and the yolk cook at different temperatures, right?

So the white cooks at about 85 degrees Celsius, while the yolk cooks at about 65.

So if you cook the yolk perfectly, then the white is runny, and if you cook the white perfectly, then the yolk is overcooked.

Right.

So Italian engineers looked into this.

They thought they must.

Of course, yeah.

They were like, we can find the perfect solution.

And they say they have, and they've published a paper in Nature Communications Engineering.

Do you want the recipe of how to do it?

I do, yes.

Okay.

So you need not one pan, but two.

Okay.

You might have lost me there to be honest.

And you can't do it in a couple of minutes.

You need exactly 32 minutes.

32.

Yeah.

So you keep one pan at 100 degrees, so boiling, and the other pan at 30 degrees, and then you move the egg between the two pans every two minutes for 32 minutes.

Wow, did you do this?

Yeah, of course I gave it a go.

So I'm in my kitchen and in front of me I've got a science paper that I'm going to try and follow like it's a recipe.

So I need to alternate an egg between a pan of boiling water kept at 100 degrees Celsius and a bowl kept at 30 degrees Celsius.

So I think it's time to start my timer.

There we go and in goes my egg.

So two minutes in boiling.

Okay, so I'm going to transfer my egg from the boiling pan into the warm pan.

Right, so now it's going to sit there for another two minutes.

So, I just have to do this back and forth, transferring every two minutes for the next 32 minutes.

So, that's 16 times.

This had better be the perfect egg.

Three, two, one.

Okay, done.

Right, egg out quickly.

So, let's give this a go.

Oh,

it is solid.

Oh no.

There is nothing dunkable about this.

I must have gone wrong.

Worth it?

Definitely not.

Glad I did it though?

Yeah.

So this was not a successful experiment.

Did you eat your solid egg?

And I did get some kitchen chores done while cooking the egg.

I said in your two-minute interval.

Exactly.

I did sort of 30 seconds of unloading the dishwasher, then running over to the hob, moving it.

So it's quite an annoying cooking process.

But, you know, if it works, I'm all for it.

I think the mistake I made was that I didn't keep the 30-degree pan at consistent enough a temperature.

So I'm blaming myself, not the science for this one.

Well, thank you so much, Caroline Steele.

It was great to have you on the programme.

And we will add our egg instructions to our programme page as well.

So if you give making the perfect science-based boiled egg a go, send your results to insidescience at bbc.co.uk.

And if I'm going to get home in time to make the perfect boiled egg for my tea, I'd better get my pans on pretty quickly.

So I will see you next time.

You have been listening to BBC Inside Science with me, Victoria Gill.

The producers were Sophie Ormiston and Jerry Holt.

Technical production was by Gareth Tyrrell.

The show was made in Cardiff by BBC Wales and West.

To discover more fascinating science content, head to bbc.co.uk, search for BBC Inside Science and follow the links to the Open University.

Until next week, thanks for listening and bye-bye.

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