Episode 2 Blow Your Mind


Episode 2

Dr Chris and Dr Xand return to Store Glacier in Greenland with a team of top experts and explorers to find out more about glaciers and icebergs.


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BOTH: We are Dr Chris and Dr Xand van Tulleken.

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-And we're tracking down the most awesome...

-Incredible...

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BOTH: And epic things in the universe!

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Come with us and discover unbelievable things...

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that will blow your mind!

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Blow Your Mind will be bringing you loads of top experts

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and scientists to help you find out more about some amazing stuff

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from the Arctic to elephants, spaceships to sharks,

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and this week, it's all about ice. Yes, frozen water.

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So, hold on to your brains.

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Cos here's what's coming up!

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We'll find out exactly what makes a glacier move,

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find the plughole deep inside a blue lake,

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and watch some super speed-bergs on the move.

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So, Chris, you've kept me waiting all day to find out more

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about what you and the scientists

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got up to on the Store Glacier in Greenland.

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You're not going to keep me waiting any longer, are you?

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Xand, would I do that to you?

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Yes, you probably would, actually.

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It was absolutely incredible to see the new iceberg forming,

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and you said the glacier you were on

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was the size of 4,000 football pitches

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and yet it's actually moving

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the length of two double-decker buses every day.

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So what I want to know is, how? How does it move?

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It's so huge, you'd think it would be difficult to move at all.

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Well, it is moving and we showed how the experts discovered

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that it is moving very fast.

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There are different theories about how it moves, so check this out.

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Today's team of intrepid explorers and scientists are...

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Chris Packham, wildlife and nature expert.

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Dr Helen Czerski, physicist and oceanographer.

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Andy Torbet, extreme explorer and glacial diver.

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Doug Allan, polar cameraman and glacial diver.

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Jason Box and Michelle Koppes, glaciologists and ice experts.

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The team headed to the centre of the glacier

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to carry out experiments to prove Helen's theory

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about how the glacier moves.

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Something is helping it along.

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The icebergs form mostly in the summer,

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so the glacier is flowing fastest in the summer.

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And we think there are some clues to why that happens right up ahead.

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This is what is known as a blue lake.

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It's a lake that's formed 15km into the glacier

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and it's a sensational, beautiful area of water

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more than a kilometre wide.

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There were half a dozen of these blue lakes on Store Glacier

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and they appeared in the spring when some of the ice melts

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and the water begins to form pools which become blue lakes.

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There is a theory that eventually the water from the blue lake

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drains to the bottom of the glacier,

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causing it to slide along the bedrock.

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So what we're really trying to do is try to figure out,

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where does this water go

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and is it contributing to more calving

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at the terminus of the glacier?

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So what's happening from here all the way to the end.

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So what Michelle was saying was that the water in this lake

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might drain to the front of the glacier,

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causing calving events or icebergs to break off.

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The team wanted to find out how much water was in the lake

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before it drained.

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The danger of doing an experiment at a blue lake

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is that no-one knew when it might crack open and empty.

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Ice expert Jason Box has been studying this blue lake

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and his results show it should have drained already.

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So this lake's now two days past the average time when it would drain.

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It could go at any moment.

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The team set up a time-lapse camera

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to see what happened on the surface of the lake

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and a depth sensor to record how much water melts into it daily.

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-Got it?

-Yup.

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The depth sensor had to be attached to something heavy,

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as it needed to be positioned ten metres down, deep in the lake.

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And expert glacial diver, Andy Torbet,

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had to dive down with it to put it in place.

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I've never dived anywhere like this.

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And certainly nowhere where, at any point during the dive,

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the water can all just drain under your feet.

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I think we can kit up and get in fairly quickly.

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Do the job, put in the sensors where necessary and we'll get out

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and everything will be fine.

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Famous last words.

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HE CHUCKLES

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Um, why is he laughing?

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He's about to go into a blue lake

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that at any time could empty like a giant bathtub

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with him getting flushed down the plughole!

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I know. It's bonkers.

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But that's the kind of guy you need on an expedition like this.

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Someone fearless, like me.

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Actually, he is really incredibly safety conscious

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and he's made sure everything is being done as safely as possible.

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I'm glad to hear it.

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Now, how are these blue lakes

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supposed to help the glacier move towards the sea?

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Well, this is how it works.

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Now, imagine these ice cubes are a glacier

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weighing billions and billions of tonnes.

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-Hmm.

-HE GROANS

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Not like that!

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Now, they're stuck on the bedrock, but if I pour water on it

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so it flows under the glacier...

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-Like the water draining from the blue lake?

-Exactly.

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Watch what happens.

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-Oh, yeah.

-Yes.

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Oh, there we go. It's moving.

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And now they slip down the dish and move easily into the sea.

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What an amazing demonstration. It was just like being there!

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Believe me, it wasn't.

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Diving into a blue lake is really dangerous

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because the water could drain at any time.

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If that happened when Andy and Doug were in there,

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they would have been sucked right down with it.

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Three, two, one... Jump.

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You should never, ever dive into any icy water.

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Only experts with experienced safety teams

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should ever attempt anything like this.

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It's absolutely beautiful down here. All these shades of...

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white...

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and blue.

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I'm going to...

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..try and place this...sensor here.

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When the ice melts, the water level in the lake rises

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and this device will tell the team exactly by how much.

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To push further out...

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..into the middle.

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Let's have a bit of an explore

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and see if you can find where this plughole is, eh?

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Despite the dangers,

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Andy couldn't help himself from exploring to find the plughole.

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Chris, that does look really amazing, but really,

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this thing could go at any time and he's swimming merrily further down.

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-Is he mad?

-Far from it, Xand.

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He's an explorer, like me, and his instinct is to find things out.

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Remember, there's a full safety team above him

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and, of course, cameraman Doug is down there too.

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Wow, I mean, what Doug is doing is really impressive.

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He's swimming around too and he's having to operate a massive camera.

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The thing is, I just can't get the sound

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of a massive toilet flushing out of my head.

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I'd hate to see these guys getting washed away.

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-Imagine how worrying it was at the time.

-Oh!

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Doug...

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There's a big...big cave here going straight down.

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-Andy's found the lake's giant plughole...

-Let's go have a look.

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..and decided to go down it.

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It's pretty dark in here.

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It's definitely getting narrower.

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This was incredibly dangerous as he could have got stuck.

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No way.

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It's getting too tight.

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It's getting way too tight.

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I'm still...nowhere near the bottom.

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40 minutes on the dive now. 41, now.

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It's cold and they'll be using air quickly,

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so they'll be out very soon, whatever they're doing.

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Andy couldn't get further into the plughole and, thankfully,

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decided to come out.

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But the extreme cold started to cause a much more urgent problem.

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HE BREATHES HEAVILY I need to surface.

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I think this air hose is freezing up.

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Ice was blocking Andy's air supply, making it harder for him to breathe.

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It was time to get him out.

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In this sort of environment,

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you can only do so much about trying to fix your kit under water.

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There comes a point where you just need to sack it and go home.

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In one piece.

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Absolutely. But what a successful dive.

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Not only did Andy position the sensor deep in the glacier,

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he also located the entrance to the plughole.

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So, with all the equipment set up,

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the team decided to head back to base camp for a few days.

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That is mind-blowing.

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I can't believe that something, or somewhere actually,

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can be so, so beautiful and so scary at the same time.

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I mean, at any point, that lake could have drained

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and sucked the divers through its massive plughole,

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never to be seen again.

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You're right. It's terrifyingly beautiful.

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But the question is, did the sensor do its job?

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And do they get the results for their water depth test?

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Do you want to find out?

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Of course I want to find out! That's why I'm here.

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-And that's why we're watching.

-All right. Well, watch, then.

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The team didn't know what they'd find

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when they headed back a few days later.

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The entire lake could have drained and disappeared,

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taking all their equipment with it.

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The lake is quite definitely still there. It hasn't drained.

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And it... The lake's got bigger so it looks as though it's been rising.

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-It's filled up.

-Helen was right.

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The lake had risen so much

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that the time-lapse camera they left behind

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was almost underwater.

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This meant that Andy had to get back in the lake,

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just to get to the equipment.

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And Helen was really worried about him.

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I just want him out of the water as quickly as possible.

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I'm finding, like...

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Finding it a bit stressful watching him.

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I know he's good, and I know he's a good swimmer,

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and he knows what he's doing in the water, but...

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..this water is not a human habitat.

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Cup of tea, I think.

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Andy's bravery paid off

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and the footage from the time-lapse camera was amazing.

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I love the way that you can see the little bits blown by the wind.

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Because they're speeded up,

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they're just zooming across the field of view.

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Yeah, we call those speed-bergs.

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See that one? Nee-ow...

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Speed-bergs. Wow!

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But it's the results from the depth sensor

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that they'd left deep in the lake

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that gave them an accurate measurement

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of how much the water level has risen.

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It looks like it filled on... You can see on this axis, it's...

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Let's call that, like, 18 to 25.

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-Seven metres.

-Yeah. That's impressive.

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-That's a lot of water.

-Right.

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The results show that in one part of the lake,

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the water had risen by seven metres, which is loads.

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About as high as a three-storey building.

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The scientists calculated that this lake

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held over five million cubic metres of water,

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which is a mind-blowing amount.

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To give you an idea,

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that's roughly the same as 2,000 Olympic swimming pools.

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The team had come to the blue lake

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to find out if it held enough water to move a glacier.

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These results showed that the combined amount of water

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from all the blue lakes on Store

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would definitely be enough to move it towards the sea,

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where it creates icebergs.

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That was amazing stuff. So now, we know how an iceberg is made.

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Gravity is pulling the glacier down towards the sea anyway,

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but the lakes on the glacier's surface

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are draining to the bottom of the glacier,

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which helps it slide along faster.

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And when it gets to the sea, chunks break off to form icebergs.

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Science made simple.

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Simple? Are you kidding?

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That expedition and those experiments took for ever to plan.

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The amazing results took a lot of blood, sweat and tears

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and the team faced a lot of danger in very difficult conditions.

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-Anyway, that is our journey over for today, Xand.

-I hate this moment.

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It's all so exciting. I want to find out more, more, more about icebergs.

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Well, there is plenty more, more, more to see.

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So join us next, next, next time

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when we will bring you much, much, much

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more brilliant stuff that will...

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BOTH: Blow, blow, blow your mind.

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Doctors Chris and Xand van Tulleken return to Store Glacier in Greenland with a team of top experts and explorers to find out more about glaciers and icebergs. In this episode they find out exactly what makes a glacier slide towards the sea. Diver Andy Torbet dives to the bottom of a blue lake in search of a giant plug hole that could drain the lake at any time and they see amazing time-lapse pictures of the lake which reveal the existence of speedbergs.


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