0:00:02 > 0:00:04BOTH: We are Dr Chris and Dr Xand van Tulleken.
0:00:04 > 0:00:07- And we're tracking down the most awesome...- Incredible...
0:00:07 > 0:00:11BOTH: And epic things in the universe!
0:00:21 > 0:00:22BOTH: Come with us
0:00:22 > 0:00:27and discover unbelievable things that 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 > 0:00:43and this week it's all about ice. Yes, frozen water.
0:00:43 > 0:00:46- So, hold on to your brains. - Here's what's coming up.
0:00:47 > 0:00:49From the enormous to the tiny,
0:00:49 > 0:00:54I take on the smallest inhabitants of the glacier - mosquitoes.
0:00:54 > 0:00:57And we find out a huge surprise about sea temperature
0:00:57 > 0:00:59at the bottom of the glacier.
0:00:59 > 0:01:03And, we see a mammoth new mega-berg being created,
0:01:03 > 0:01:06140 million tonnes of ice.
0:01:06 > 0:01:10Another load of cracking stuff for us to see today, Chris.
0:01:10 > 0:01:14And I, for one, can't wait. I've already seen so many exciting things!
0:01:14 > 0:01:17Those spectacular holes, the moulins, and Andy discovering all those
0:01:17 > 0:01:20massive ice tunnels below the moulins.
0:01:20 > 0:01:22And it was really scary when the tunnel roof collapsed,
0:01:22 > 0:01:24he doesn't have an easy time of it, does he, Andy?
0:01:24 > 0:01:25Well, he's an explorer, Xand.
0:01:25 > 0:01:28That's the job description, that's how it got to go,
0:01:28 > 0:01:30and that's why we went to Greenland in the first place.
0:01:30 > 0:01:33To try and find out more about the glaciers and the icebergs.
0:01:33 > 0:01:36And the team were learning things the whole time, but we weren't just
0:01:36 > 0:01:39learning up on the glacier, there was plenty happening in the sea,
0:01:39 > 0:01:40as well.
0:01:44 > 0:01:47There were over 20 experts involved in the expedition.
0:01:47 > 0:01:51The main team members in today's show are...
0:01:51 > 0:01:54Chris Packham. Wildlife and nature expert.
0:01:55 > 0:01:58Expedition doctor, and all round brave guy, me.
0:02:00 > 0:02:04Andy Torbet, extreme explorer and glacial diver.
0:02:05 > 0:02:10Alun Hubbard and Nolwenn Chauche, glaciologists and ice experts.
0:02:12 > 0:02:14The team were aboard the research ship Gambo,
0:02:14 > 0:02:16carrying out an exciting experiment.
0:02:16 > 0:02:20Alun had some clever equipment, called Side Scanning Sonar,
0:02:20 > 0:02:22which would help map the front of the glacier.
0:02:25 > 0:02:28That's the actual equipment that sends out the sound wave,
0:02:28 > 0:02:32the acoustic wave, which bounces off the glacier and we pick it up.
0:02:32 > 0:02:34So, Alun fired sound signals at the glacier,
0:02:34 > 0:02:37which pinged back to his computer.
0:02:37 > 0:02:41It then converted those signals into a map of what the ice will
0:02:41 > 0:02:43look like underwater.
0:02:43 > 0:02:46But, to get a good scan, the research boat needed to sail
0:02:46 > 0:02:50up close to the cliff, near to where the icebergs could break off.
0:02:51 > 0:02:52RUMBLING
0:03:00 > 0:03:02- Just a little bit. - Just a little bit.
0:03:03 > 0:03:06The results from this experiment could be ground-breaking.
0:03:06 > 0:03:09But, before they could complete the scan,
0:03:09 > 0:03:12the giant glacier reminded them who's boss.
0:03:34 > 0:03:35What happened?
0:03:35 > 0:03:39We had a carving event, and what it triggered off was a large
0:03:39 > 0:03:45lump from under the water that shot up really high out of the water.
0:03:45 > 0:03:49That is quite a minor carving event, I hate to say, Chris.
0:03:49 > 0:03:52Whoa! How scary is that?
0:03:52 > 0:03:53And there's no way of knowing
0:03:53 > 0:03:55when these things are going to happen, is there?
0:03:55 > 0:03:56That's exactly right.
0:03:56 > 0:03:58They were really lucky on that occasion because they had
0:03:58 > 0:04:02just gone past the area where that had happened just minutes before.
0:04:02 > 0:04:04Did they still manage to get the results of their survey?
0:04:04 > 0:04:06I bet they didn't. I bet they chickened out.
0:04:06 > 0:04:09Xand, explorers like me know no fear.
0:04:09 > 0:04:10After the experiences I had in Greenland,
0:04:10 > 0:04:13nothing can surprise, shock or frighten me.
0:04:13 > 0:04:15Boo!
0:04:15 > 0:04:16Wow, it's true.
0:04:16 > 0:04:20Back on the Gambo, the fearless experts were still out at sea,
0:04:20 > 0:04:23analysing the results as they came in.
0:04:24 > 0:04:25What can you see there?
0:04:25 > 0:04:28OK, so we've got the glacier from here on the sea bed here.
0:04:28 > 0:04:30- That's the boat, here.- Yeah.
0:04:30 > 0:04:33The floor at the moment is about 400 metres here.
0:04:33 > 0:04:37So, we're looking at cliffs outside that are about 80 to 100 metres
0:04:37 > 0:04:40tall at their highest, but there's 400 metres beneath the water.
0:04:40 > 0:04:42Yeah, at least, yeah.
0:04:42 > 0:04:45So, the scan showed that there was four times as much
0:04:45 > 0:04:47ice below the water as above it.
0:04:47 > 0:04:49But it also revealed something else -
0:04:49 > 0:04:53the base of the ice wall was undercut, which meant it was
0:04:53 > 0:04:58cut back into the glacier so the top was unsupported and overhanging.
0:04:58 > 0:04:59How deep is that undercut?
0:04:59 > 0:05:02At the moment, it's about 150 metres.
0:05:02 > 0:05:04- 150 metres?- At least.
0:05:05 > 0:05:09So, the undercut went back 150 metres, which is
0:05:09 > 0:05:11longer than a football pitch,
0:05:11 > 0:05:15and all the ice hanging above it was unsupported and unstable,
0:05:15 > 0:05:18which could explain why it collapses into the sea so often.
0:05:22 > 0:05:26- That is amazing, how much ice is below the water.- Exactly, Xand.
0:05:26 > 0:05:29And the undercut is interesting. Let me show you, using this iceberg.
0:05:29 > 0:05:34- Now, hold that.- This is an iced cake.- No, Xand, it's an iceberg.
0:05:34 > 0:05:37Now, the water, at the bottom near the sea bed,
0:05:37 > 0:05:40erodes the iceberg like this.
0:05:40 > 0:05:47Melting it gradually until this top part here forms an overhang,
0:05:47 > 0:05:50weighing sometimes thousands or millions of tonnes.
0:05:50 > 0:05:56And eventually, this bit just breaks off and forms a new berg.
0:05:56 > 0:06:00Chris, there are now millions of tonnes of cake all over the floor!
0:06:00 > 0:06:02- I was going to eat that! - Yeah, sorry about that.
0:06:02 > 0:06:04I'm afraid the rest of the cake is mine, as well.
0:06:08 > 0:06:09'Nice, Xand.'
0:06:11 > 0:06:14Now the team knew of the massive undercut in the glacier,
0:06:14 > 0:06:16they wanted to investigate why it formed.
0:06:20 > 0:06:23Nolwenn thought the temperature of the ocean may be one of the
0:06:23 > 0:06:27reasons, so he lowered a temperature measuring probe to the sea bed.
0:06:31 > 0:06:34And the temperature readings were astonishing.
0:06:34 > 0:06:37- On the surface we get relatively warm water.- Yeah.
0:06:37 > 0:06:40It's cooling down pretty quickly and, after that,
0:06:40 > 0:06:45it's warming as we go further down. With a maximum at 2.7 degrees.
0:06:45 > 0:06:50And all this water, from 400 metres to the bottom at 800,
0:06:50 > 0:06:52is at 2.4 degrees.
0:06:54 > 0:06:56These results were really surprising,
0:06:56 > 0:07:00the water on the sea bed was really warm, well above freezing.
0:07:00 > 0:07:05This warmer water melts the glacier at its base, forming the undercut.
0:07:07 > 0:07:09- Hm, top data.- Yeah. Really great, yeah.
0:07:12 > 0:07:14Now THAT is mind-blowing.
0:07:14 > 0:07:17That the sea is actually warmer the further down you go.
0:07:17 > 0:07:21And that is helping to create the undercut of the ice cliff
0:07:21 > 0:07:23underwater, which is what makes the bergs break off?
0:07:23 > 0:07:26That's exactly right, you were paying attention, Xand. For once.
0:07:26 > 0:07:29But you know, it's not just massive things, like ice cliffs
0:07:29 > 0:07:32and polar bears, that you need to worry about in Greenland.
0:07:32 > 0:07:35- INSECT BUZZING - There are some really tiny things that can hurt you, too.
0:07:35 > 0:07:38We came to Greenland prepared for the massive dangers
0:07:38 > 0:07:40the glacier would throw at us.
0:07:40 > 0:07:45But nobody expected a much smaller, more annoying threat - mosquitoes.
0:07:45 > 0:07:47MOSQUITOES BUZZ
0:07:47 > 0:07:49During the short Arctic summer,
0:07:49 > 0:07:52the mosquitoes survive on nectar from plants.
0:07:52 > 0:07:55But they prefer to drink the blood of mammals.
0:07:55 > 0:07:56And that's where we came in.
0:07:56 > 0:07:59Handily, I'm an expert in tropical medicine,
0:07:59 > 0:08:04but I didn't expect to be using my tropical skills in Greenland.
0:08:05 > 0:08:06'I decided to find out
0:08:06 > 0:08:11'if some people were more attractive to the mosquitoes than others.'
0:08:11 > 0:08:12Good news, everyone.
0:08:12 > 0:08:14I've developed another experiment, it's going to be painful,
0:08:14 > 0:08:15and I need a volunteer.
0:08:15 > 0:08:19'The team volunteered brave extreme ice explorer
0:08:19 > 0:08:21'Andy Torbet to join me.'
0:08:21 > 0:08:22I hate you.
0:08:22 > 0:08:25'Who, as you can see, was less than happy.'
0:08:25 > 0:08:27We're going to sit here with our shirts off,
0:08:27 > 0:08:30no insect repellent on, and see who gets more bites.
0:08:30 > 0:08:34- I like straightforward experimental protocols.- You're a genius.
0:08:34 > 0:08:37So, the person bitten the most would have produced the most
0:08:37 > 0:08:39chemicals attractive to mosquitoes.
0:08:40 > 0:08:43So, obviously, there is a competitive element to this.
0:08:43 > 0:08:46Whoever gets bitten more loses, blatantly.
0:08:48 > 0:08:51So, what they'll be doing is smelling us.
0:08:51 > 0:08:53And they're, first of all, attracted to our carbon dioxide,
0:08:53 > 0:08:56and they'll be following the carbon dioxide trail in.
0:08:56 > 0:09:00And when they get close they start to smell the sweat and body odour.
0:09:00 > 0:09:03Some people have chemicals in their sweat that the mosquitoes
0:09:03 > 0:09:04really like.
0:09:04 > 0:09:06- Ah!- There you are.
0:09:06 > 0:09:10They're all females. And this one is swollen with blood.
0:09:10 > 0:09:12Ugh! Ugh! Ugh!
0:09:16 > 0:09:18- Oh, gross!- I know, it was awful. I was there.
0:09:18 > 0:09:20No, I'm not talking about that.
0:09:20 > 0:09:23I'm saying, is there anything worse than seeing your twin brother
0:09:23 > 0:09:26bare chested and scratching himself? Well, it turns out there is.
0:09:26 > 0:09:29It's seeing your twin brother bare chested and scratching himself,
0:09:29 > 0:09:30on TV!
0:09:30 > 0:09:32MOBILE RINGS
0:09:32 > 0:09:36Hold on. Hello? No, Mum, I can't speak at the moment. I'm on TV.
0:09:37 > 0:09:41Apparently, she knows I'm on TV. Yes, Mum. Yes, yeah.
0:09:41 > 0:09:44Look, I have to go. Yes, sorry. Sorry.
0:09:44 > 0:09:47I'm guessing she didn't like the Tarzan impersonation either?
0:09:47 > 0:09:51- She said she's told me before... - BOTH: Keep your shirt on in public.
0:09:51 > 0:09:54But the thing is, we needed to see what happened and do the experiment.
0:09:54 > 0:09:57All right. And we need to see if anything good will come out of this,
0:09:57 > 0:10:00like you putting your shirt back on!
0:10:00 > 0:10:03There is absolutely nothing on you. So, how're we doing?
0:10:03 > 0:10:11- I've got one there.- Two. Three. - Four.- Four.- Five.- Five. My go.
0:10:11 > 0:10:14Eight, nine, ten, 11, 12, 13, 14, 15, 16, 17.
0:10:14 > 0:10:16So, why have you got 32 on your right side
0:10:16 > 0:10:18and only two on your left side?
0:10:18 > 0:10:20I think it's the downwind side.
0:10:20 > 0:10:22They're attracted to the CO2 from there,
0:10:22 > 0:10:25and they're not getting blown away.
0:10:25 > 0:10:28'So, at the end of our highly technical mosquito experiment,
0:10:28 > 0:10:33'Andy had around five bites, and I had around 34.'
0:10:33 > 0:10:35So, they're more attracted to you, you're getting bitten more.
0:10:35 > 0:10:38My sweat is more appealing to mosquitoes than yours
0:10:38 > 0:10:40so all I've won is more mosquito bites.
0:10:42 > 0:10:45I think we learned a few interesting things there about mosquitoes.
0:10:45 > 0:10:47I think you might have proved a few other things, as well.
0:10:47 > 0:10:50Like, how Mum was right to tell you to keep your shirt on in public.
0:10:50 > 0:10:53- MOBILE TEXT ALERT - Hold on. I knew I shouldn't have brought this phone into the studio.
0:10:53 > 0:10:58- Admiring fan, is it?- Well, sort of. - Is it Mum again? Give me that!
0:10:59 > 0:11:03"Christopher, why can't behave more like your darling brother,
0:11:03 > 0:11:07"Xand, who knows when to keep his shirt on." I don't think she's happy.
0:11:08 > 0:11:11Your impression of Mum is frighteningly accurate.
0:11:11 > 0:11:13But she obviously hasn't heard about the time when you went...
0:11:13 > 0:11:15Moving right along.
0:11:15 > 0:11:17Now, I'm sure if Chris could talk right now
0:11:17 > 0:11:20he would tell you that this next bit is about something else completely
0:11:20 > 0:11:24awesome, so don't go anywhere, stay in that chair and prepare yourself.
0:11:24 > 0:11:26Mmmph. Thank you, Xand.
0:11:26 > 0:11:28The results the team gathered had been
0:11:28 > 0:11:31crucial in understanding how the glaciers move and,
0:11:31 > 0:11:34when the ice front reaches the sea, the base melts,
0:11:34 > 0:11:38causing an overhang that breaks off, forming icebergs.
0:11:38 > 0:11:40But to do these experiments, Chris Packham
0:11:40 > 0:11:44and the team had to sail the research boat, the Gambo,
0:11:44 > 0:11:49dangerously close to the huge, unstable ice front.
0:11:49 > 0:11:51And suddenly, the worst happened.
0:11:53 > 0:11:55What are we doing, Norman? Are we out of here?
0:11:55 > 0:11:57Yeah, yeah, we're escaping.
0:11:59 > 0:12:01Wow, look at that!
0:12:01 > 0:12:05A HUGE chunk of ice split away from the glacier.
0:12:05 > 0:12:10Compared to any ice carvings we'd seen so far, this was gigantic.
0:12:11 > 0:12:16That is a major carving event. Look at the wave! Look at the wave!
0:12:17 > 0:12:18Look at the wave!
0:12:18 > 0:12:21- Is that going to be a monster? - It looks big.
0:12:21 > 0:12:22It was massive on the front.
0:12:22 > 0:12:25It hasn't reached us yet, but it looks really big.
0:12:27 > 0:12:31'Up at base camp, we were seriously worried about the crew on the boat.'
0:12:31 > 0:12:34The Gambo, where is the Gambo? They were right down there next to it.
0:12:37 > 0:12:39This was the birth of a mega-berg.
0:12:40 > 0:12:43140 million tonnes of ice, travelling
0:12:43 > 0:12:46so fast it could easily swamp the Gambo.
0:12:48 > 0:12:50Thankfully, the crew managed to steer themselves
0:12:50 > 0:12:55out of the path of this new, massive mega-berg, and away to safety.
0:12:58 > 0:13:00Now that would... BOTH: Blow Your Mind!
0:13:00 > 0:13:03That is just the most incredible thing I have ever seen.
0:13:03 > 0:13:06And I just saw it on telly, I mean, you were actually there!
0:13:06 > 0:13:10- It was just completely awesome. - We have to see that again, Chris.
0:13:10 > 0:13:13- I bet everyone at home wants to watch a replay, too.- Absolutely.
0:13:13 > 0:13:15Who wouldn't? Guys, run the replay.
0:13:16 > 0:13:21Whoa! That was absolutely massive.
0:13:22 > 0:13:27Look at that wall of water, it was an incredible sight.
0:13:27 > 0:13:31- I am, literally, speechless! - No you're not, you just said that.
0:13:31 > 0:13:35- All right. It was awesome.- I know, I was there.- This has just been great.
0:13:35 > 0:13:38I mean, I learned so much about icebergs and glaciers.
0:13:38 > 0:13:41And I've learned not to take my shirt off
0:13:41 > 0:13:42when there are TV cameras around.
0:13:42 > 0:13:45Well, I think Mum is going to be extremely pleased.
0:13:45 > 0:13:48Well, there are loads more incredible things to show you.
0:13:48 > 0:13:51So, join us next time so we can...
0:13:51 > 0:13:52BOTH: Blow Your Mind!