0:00:02 > 0:00:04We are Dr Chris and Dr Xand van Tulleken.
0:00:04 > 0:00:07And we're tracking down the most awesome, incredible
0:00:07 > 0:00:11and epic things in the universe!
0:00:21 > 0:00:25Come with us and discover unbelievable things...
0:00:25 > 0:00:27that will blow your mind!
0:00:27 > 0:00:30Blow Your Mind will be bringing you loads of top experts
0:00:30 > 0:00:35and scientists to help you find out more about some amazing stuff.
0:00:35 > 0:00:38From the Arctic to elephants, spaceships to sharks,
0:00:38 > 0:00:41and this week it's all about ice.
0:00:41 > 0:00:43Yes, frozen water.
0:00:43 > 0:00:46- So, hold on to your brains... - BOTH: Here's what's coming up!
0:00:48 > 0:00:51Today, we'll show you some massive icebergs, or mega-bergs,
0:00:51 > 0:00:56as they break off from glaciers and can be as big as cities.
0:00:57 > 0:01:00We'll find out how fast a glacier moves
0:01:00 > 0:01:03and we'll see a mega-berg being born.
0:01:05 > 0:01:08Xand, how much you know about icebergs?
0:01:08 > 0:01:11I mean, have you got any idea where they come from, for example?
0:01:11 > 0:01:13Right, I CAN do this...
0:01:13 > 0:01:15Erm, you know in our freezer at home,
0:01:15 > 0:01:17it gets clogged with ice sometimes.
0:01:17 > 0:01:20So I think it's that - and then the bits break off and
0:01:20 > 0:01:21float away in the ocean.
0:01:21 > 0:01:24Right, so you don't know anything about icebergs, then.
0:01:24 > 0:01:26To be honest, I don't know exactly how they're made
0:01:26 > 0:01:29but I do know that they're big, they float and they melt.
0:01:29 > 0:01:33You're right that they float. And you're right that they're big.
0:01:33 > 0:01:35- But have you any idea HOW big?- No.
0:01:35 > 0:01:39Well, I've been on an iceberg in Greenland.
0:01:39 > 0:01:41This iceberg was really, really, REALLY big!
0:01:41 > 0:01:454,000 million tonnes of ice!
0:01:45 > 0:01:47Where do icebergs come from?
0:01:47 > 0:01:49How are they actually formed?
0:01:49 > 0:01:52How does that that amount of ice actually come about?
0:01:52 > 0:01:54It doesn't just plop out of a fridge and grow.
0:01:54 > 0:01:55To try and find out,
0:01:55 > 0:01:58I joined a whole lot of scientists to discover the answer.
0:01:58 > 0:02:01And, Xand, I think YOU need to watch this...
0:02:01 > 0:02:05This amazing jumble of icy pinnacles and valleys,
0:02:05 > 0:02:07cracks and crevices,
0:02:07 > 0:02:09is Store Glacier in Greenland.
0:02:09 > 0:02:13And it's one of the last unexplored wildernesses in the world.
0:02:15 > 0:02:17It's where some of the most gigantic, awesome,
0:02:17 > 0:02:21spectacular things anywhere on the planet start their lives -
0:02:21 > 0:02:24icebergs.
0:02:24 > 0:02:26Some icebergs are massive
0:02:26 > 0:02:29and can weigh up to 20 billion tonnes
0:02:29 > 0:02:31and are as high as skyscrapers.
0:02:32 > 0:02:35'I joined a team of scientists, experts
0:02:35 > 0:02:39'and explorers from all over the world on an adventure to
0:02:39 > 0:02:43'Greenland to find out more about these frozen marvels.'
0:02:45 > 0:02:49Here are the intrepid team members you'll meet today.
0:02:49 > 0:02:51Doctor Helen Czerski,
0:02:51 > 0:02:53physicist and oceanographer.
0:02:53 > 0:02:56She wanted to uncover and understand what's happening
0:02:56 > 0:03:00deep within the Greenland ice sheet and the icebergs.
0:03:01 > 0:03:02Chris Packham,
0:03:02 > 0:03:04naturalist and wildlife expert,
0:03:04 > 0:03:08obsessed by the natural world since he was a young boy.
0:03:08 > 0:03:10He was keen to explore the animals
0:03:10 > 0:03:13and ecosystems around these icy wildernesses.
0:03:15 > 0:03:17Doug Allan,
0:03:17 > 0:03:18polar cameraman and diver.
0:03:18 > 0:03:21He'd be filming in some of the most dangerous
0:03:21 > 0:03:25and difficult environments to capture all of the amazing images
0:03:25 > 0:03:27on camera.
0:03:28 > 0:03:30Doctor Alun Hubbard, glaciologist.
0:03:30 > 0:03:34Alun is an expert in all things icy.
0:03:34 > 0:03:35And he'd be leading the research
0:03:35 > 0:03:38and experiments taking place on the glacier.
0:03:40 > 0:03:43The whole team were risking their lives in one of the most
0:03:43 > 0:03:46changeable and violent environments in the world.
0:03:46 > 0:03:50So, they needed a reliable and brave doctor to join them
0:03:50 > 0:03:52and keep them safe.
0:03:52 > 0:03:54I'm sure you can guess who they asked...
0:03:57 > 0:03:59Amazing doctor extraordinaire,
0:03:59 > 0:04:01I was essential for the team,
0:04:01 > 0:04:03as I was there to keep everyone well,
0:04:03 > 0:04:07which, in those severe conditions, was harder than it looks.
0:04:08 > 0:04:10Did you know that Greenland's glaciers
0:04:10 > 0:04:13pump out 20,000 icebergs a year?
0:04:13 > 0:04:16And 95% of all icebergs in the northern hemisphere
0:04:16 > 0:04:21come from Greenland, including the one that sank the Titanic.
0:04:21 > 0:04:24One of the mightiest of all Greenland's glaciers is Store.
0:04:24 > 0:04:28It's an incredible landscape of ice, with cliffs beyond your imagination.
0:04:28 > 0:04:32Everything is a creaking, crunching wonderland of ice.
0:04:32 > 0:04:36It's so massive, it's hard to take it all in, even when you're there.
0:04:36 > 0:04:40Store Glacier is about the same length as 4,000 football pitches.
0:04:40 > 0:04:434,000 very slippery football pitches, that is!
0:04:43 > 0:04:464,000 super-slippery football pitches? That is impressive!
0:04:46 > 0:04:48- Let's have a look...- Gladly!
0:04:52 > 0:04:55Store Glacier is on the west coast of Greenland.
0:04:55 > 0:05:00And it's basically a 400km river of solid ice.
0:05:00 > 0:05:02Where it meets the sea,
0:05:02 > 0:05:06it has a cliff of ice that's an unbelievable 8km wide.
0:05:06 > 0:05:11That's more than four miles. The team based ourselves here,
0:05:11 > 0:05:14in a camp overlooking that ice cliff.
0:05:15 > 0:05:20All of this ice is moving. It's creeping downwards all the time.
0:05:20 > 0:05:22Partly, that happening because of gravity
0:05:22 > 0:05:25pulling the ice downwards towards the sea,
0:05:25 > 0:05:28down here to where icebergs calve off the front.
0:05:28 > 0:05:30But if that was the only thing that's going on,
0:05:30 > 0:05:34we wouldn't see as many icebergs down here as we do.
0:05:34 > 0:05:36So there is something else...
0:05:36 > 0:05:39Physicists like Helen study how the world works.
0:05:39 > 0:05:41And although they are really clever,
0:05:41 > 0:05:44there are still loads of things they haven't got the answers to yet,
0:05:44 > 0:05:46especially about glaciers and icebergs.
0:05:48 > 0:05:54This astonishing glacier releases a mind-boggling 15 billion tonnes,
0:05:54 > 0:05:58yes, 15 billion tonnes of ice into the sea every year.
0:05:58 > 0:06:01And the scientists wanted to find out how...
0:06:04 > 0:06:08On our very first day in camp, polar cameraman Doug Allan
0:06:08 > 0:06:12was already filming a small iceberg starting life.
0:06:12 > 0:06:16This process is called calving.
0:06:16 > 0:06:19Calving...calving...
0:06:19 > 0:06:22Isn't that what a cow does when it's giving birth?
0:06:22 > 0:06:25So, is a cow giving birth to an iceberg? No, no...
0:06:25 > 0:06:27Is an iceberg giving birth to a cow?
0:06:27 > 0:06:29Sometimes I worry about you, Xand, I really do.
0:06:29 > 0:06:32Calving is also the name of the process
0:06:32 > 0:06:37when bits is of a glacier break off to create a brand-new iceberg.
0:06:37 > 0:06:40So, just to be absolutely clear...
0:06:40 > 0:06:42- Are there any cows involved in this? - No.
0:06:42 > 0:06:46So, how do we know that something as gigantic
0:06:46 > 0:06:49and as heavy as the Store Glacier can move in the first place?
0:06:49 > 0:06:52- It's too slow to see.- I'm glad you asked. Take a look at this...
0:06:54 > 0:06:56These are time-lapse pictures of the glacier.
0:06:56 > 0:07:00We could work out that it was constantly moving.
0:07:00 > 0:07:04The first challenge for the team was to work out exactly how fast
0:07:04 > 0:07:05it moved.
0:07:07 > 0:07:11Alun Hubbard is a glaciologist - an expert in glaciers.
0:07:11 > 0:07:15He came up with a plan to measure the speed of the glacier.
0:07:15 > 0:07:19If he attached a GPS tracker to the front of the glacier,
0:07:19 > 0:07:22then he'd be able to record its speed
0:07:22 > 0:07:24and find out more about what happened
0:07:24 > 0:07:27when these calvings occurred.
0:07:29 > 0:07:30This was incredibly dangerous.
0:07:30 > 0:07:33To do this, Alun would have to find a part of the glacier that
0:07:33 > 0:07:35looked like it could crumble soon,
0:07:35 > 0:07:39but hopefully not whilst he was on top of it, attaching the tracker.
0:07:41 > 0:07:44Alun had decided that this was the moment to attempt this
0:07:44 > 0:07:48hair-raising experiment. So, they started getting the gear ready.
0:07:49 > 0:07:53He's calculated that if we put this device on during the time that
0:07:53 > 0:07:55we're here, it will break free.
0:07:55 > 0:07:58And we'll get all the measurements up to that point and...
0:07:58 > 0:08:02That's cutting edge. I mean, that science AT the edge!
0:08:03 > 0:08:06There wasn't enough room in the chopper for a camera team,
0:08:06 > 0:08:10so Chris Packham volunteered to take the camera and film this himself.
0:08:19 > 0:08:24The ice here is extremely unstable, breaking off all the time.
0:08:30 > 0:08:34Alun needed to be dropped on top of a precarious ice tower.
0:08:34 > 0:08:36Can you get on that?
0:08:45 > 0:08:49- He landed safely on top of the tower...- Two, three minutes, OK?
0:08:49 > 0:08:53..but needed to work quickly to fix the GPS tracker.
0:08:54 > 0:08:58This tower could have broken off into the sea at any minute,
0:08:58 > 0:09:00taking Alun with it...
0:09:02 > 0:09:04Oh, my goodness me!
0:09:05 > 0:09:07Just look at where he is!
0:09:09 > 0:09:11Frankly, that is astonishing.
0:09:13 > 0:09:17Where Alun is perched on top of this part of the glacier,
0:09:17 > 0:09:19there has to be a 100-metre drop.
0:09:21 > 0:09:25He has a couple of minutes to get that drill and get the material in.
0:09:26 > 0:09:30And frankly, if there's any movement on the ice, there is no chance...
0:09:30 > 0:09:33Oh, my goodness! I can't even look! Is he back in the chopper yet?
0:09:33 > 0:09:36No, not yet. But don't worry, he'll probably be fine.
0:09:36 > 0:09:40Wait a minute, you were there! What do you mean "probably"?
0:09:40 > 0:09:42You know what happened, just tell me!
0:09:42 > 0:09:45Can we just get back to see if he survives this?
0:09:45 > 0:09:46I can't bear the tension!
0:09:47 > 0:09:52YOU can't bear the tension? Imagine what it was like for us at the time.
0:09:52 > 0:09:54All we could do was watch and hope it would be OK.
0:09:54 > 0:09:57It's just a pillar with an enormous crack down one side of it.
0:09:57 > 0:10:00If I was going to bet on the next pillar of ice...
0:10:00 > 0:10:02..the next to go, it would be that one!
0:10:02 > 0:10:04This was completely terrifying. The pillar Alun was on
0:10:04 > 0:10:06was likely to topple soon.
0:10:06 > 0:10:09But he didn't know if it would be today.
0:10:10 > 0:10:11Oh, that is astonishing!
0:10:14 > 0:10:16OK, he's ready to go!
0:10:21 > 0:10:24Thankfully, after only 4½ minutes, he'd done it.
0:10:34 > 0:10:38The GPS tracker that Alun planted was now able to tell the team
0:10:38 > 0:10:42the exact speed the front of the glacier moved.
0:10:42 > 0:10:45I cannot believe how dangerous that was!
0:10:45 > 0:10:47- The things people put themselves through for science!- I know.
0:10:47 > 0:10:50That really was massively dangerous.
0:10:50 > 0:10:54But scarily, less than 24 hours later, this happened...
0:10:55 > 0:10:57At four o'clock in the morning,
0:10:57 > 0:11:01when sensible people were fast asleep and only unmanned cameras
0:11:01 > 0:11:05were watching, a gigantic piece of the glacier started to break away...
0:11:08 > 0:11:09Look at that!
0:11:09 > 0:11:13A massive section, including the very tower that Alun was
0:11:13 > 0:11:15standing on, has tumbled into the sea.
0:11:20 > 0:11:24It was now part of an iceberg and had taken Alun's GPS gizmo with it.
0:11:30 > 0:11:33That looked incredible! I'd love to see it again!
0:11:33 > 0:11:36I'd love to see it again as well, so let's have an instant replay.
0:11:36 > 0:11:38- Hey, replay guys! - HE CLICKS FINGERS
0:11:38 > 0:11:42What a sight to behold! It was awesome.
0:11:42 > 0:11:45The cliff started to break up and fall into the sea.
0:11:45 > 0:11:49But then the mass of ice under the water rose up to the surface,
0:11:49 > 0:11:52causing that huge wave to form.
0:11:52 > 0:11:55Luckily, the GPS tracker recorded some interesting
0:11:55 > 0:12:00- and useful results BEFORE it was swept into the sea.- Quite revealing.
0:12:00 > 0:12:04It's mean velocity is about 25 metres a day.
0:12:04 > 0:12:07That's just under 10km a year right at the ice front.
0:12:07 > 0:12:14And you can see it has varied from 10 metres a day, and just before it
0:12:14 > 0:12:18toppled in, you can see it's moving at over 50 metres a day.
0:12:18 > 0:12:20So, it's a lovely idea because we've been looking at this,
0:12:20 > 0:12:24and in my head I'd been imagining it was almost steady movement.
0:12:24 > 0:12:29But what you're saying is it speeds up and slows down as the days go on.
0:12:29 > 0:12:32So, the results showed that Store Glacier moved
0:12:32 > 0:12:35an average of around 25 metres a day.
0:12:35 > 0:12:39That's the same length as two buses, and made Store
0:12:39 > 0:12:42one of the fastest-moving glaciers in the world.
0:12:42 > 0:12:46It's absolutely mind-blowing that something so humongous
0:12:46 > 0:12:49and dense and hard can travel the same distance as the length
0:12:49 > 0:12:53- of two double-decker buses, pretty much every day!- It's phenomenal.
0:12:53 > 0:12:57It's astonishing. It's almost magical when you see the film
0:12:57 > 0:12:59run at high speed. Let's watch it again.
0:12:59 > 0:13:03It's like watching some kind of army marching or someone spreading
0:13:03 > 0:13:05- icing on a cake.- Yes, Xand,
0:13:05 > 0:13:07but I think even YOU would find it hard to get through THIS cake!
0:13:07 > 0:13:11Anyway, how do you think this glacier, or any glacier,
0:13:11 > 0:13:13keeps moving? Gravity is pulling it down towards the sea
0:13:13 > 0:13:17but there is something else helping it along. Any idea what?
0:13:17 > 0:13:21A very strong whale with a big rope attached to its tail.
0:13:21 > 0:13:22I'm not even going to answer that.
0:13:22 > 0:13:25OK, is it a crab the size of New York City?
0:13:25 > 0:13:27Xander, you're being pathetic. You're going to make ME
0:13:27 > 0:13:30- crabby in a minute.- All right, no need to be nippy! Get it?
0:13:30 > 0:13:33Crab...pincer...nippy? Forget it. I would have loved to have been
0:13:33 > 0:13:36with you in real life, though, and actually seen that.
0:13:36 > 0:13:38Can we see some more of what you did?
0:13:38 > 0:13:40Well, you can, but you're going to have to wait.
0:13:40 > 0:13:42But make sure that YOU come back because there is tonnes,
0:13:42 > 0:13:44literally TONNES more ice to see!
0:13:44 > 0:13:47- So much, it will... - BOTH: ..blow your mind!