0:00:02 > 0:00:04We 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 > 0:00:11..and epic things in the universe!
0:00:21 > 0:00:24Come with us and discover unbelievable things...
0:00:24 > 0:00:27that will Blow Your Mind!
0:00:27 > 0:00:31Blow Your Mind will be bringing you loads of top experts
0:00:31 > 0:00:36and scientists to help you find out more about some amazing stuff.
0:00:36 > 0:00:37From the arctic to elephants,
0:00:37 > 0:00:41spaceships to sharks, and this week, it's all about ice.
0:00:41 > 0:00:45Yes, frozen water. So hold on to your brains...
0:00:45 > 0:00:47Because here's was coming up.
0:00:48 > 0:00:52We once again explore the icy megalith that is Store Glacier,
0:00:52 > 0:00:55wonder at the 3-D image of the glacier underwater...
0:00:57 > 0:01:00..just as we're about to leave, Store delivers a parting gift
0:01:00 > 0:01:05of astonishing scale and incredible natural destruction and beauty.
0:01:05 > 0:01:09And we look ahead to the next leg of our incredible
0:01:09 > 0:01:11exploration, the mega-berg.
0:01:14 > 0:01:16We've been following Chris's adventure
0:01:16 > 0:01:20living on Store Glacier in Greenland with a bunch of ice scientists.
0:01:20 > 0:01:23We've seen some incredibly mind-blowing stuff,
0:01:23 > 0:01:26like massive ice tunnels big enough to fit
0:01:26 > 0:01:28two double-decker buses on top of each other inside...
0:01:28 > 0:01:31And divers diving so deep under the ice,
0:01:31 > 0:01:33the water eventually became warmer...
0:01:33 > 0:01:36And the bonkersly brave glaciologist fixing
0:01:36 > 0:01:42a GPS tracker to the top of an ice tower. It's been incredible.
0:01:42 > 0:01:45Find out more about glaciers and icebergs.
0:01:45 > 0:01:48Well, today, I'll be showing you the next step in the adventure
0:01:48 > 0:01:50as we leave our glacier in Greenland and set off
0:01:50 > 0:01:52in search of a mega-berg.
0:01:52 > 0:01:54A mega-berg?
0:01:54 > 0:01:57That sounds so cool. I bet you were sad to leave the glacier
0:01:57 > 0:01:59because you'd seen so much there,
0:01:59 > 0:02:03- but going to a mega-berg sounds even better.- It does, doesn't it?
0:02:03 > 0:02:06We were all excited to find the mega-berg, but before we left,
0:02:06 > 0:02:08the team still had a few things to do
0:02:08 > 0:02:11in their floating science lab, the Gambo.
0:02:14 > 0:02:16Aboard the Gambo, our experts are...
0:02:18 > 0:02:20..Chris Packham, wildlife and nature expert...
0:02:22 > 0:02:25..Helen Czerski, physicist and oceanographer...
0:02:27 > 0:02:30..Alun Hubbard, glaciologist and ice expert...
0:02:32 > 0:02:37..Richard Bates, geophysicist and ice expert.
0:02:40 > 0:02:42Their little research yacht, Gambo,
0:02:42 > 0:02:45had returned to the perilous waters they'd sailed during
0:02:45 > 0:02:47the sonar scanning that had helped the team
0:02:47 > 0:02:50to map out the front of the glacier.
0:02:50 > 0:02:53Chris Packham had spotted something then,
0:02:53 > 0:02:56an area of water bubbling up that could help them
0:02:56 > 0:03:00understand the route of meltwater from the glacier to the ice front.
0:03:00 > 0:03:02They returned to investigate.
0:03:04 > 0:03:08This body of water here is very different than everywhere else.
0:03:08 > 0:03:11There's brash ice everywhere and yet this is open,
0:03:11 > 0:03:14it's turbid and parts of it are boiling.
0:03:14 > 0:03:17Well, not boiling, but there's a lot of Jacuzzi action.
0:03:17 > 0:03:20Jacuzzi action, that's a pretty cool word for it.
0:03:20 > 0:03:24The plumes, these jacuzzis, I think, I suspect are absolutely
0:03:24 > 0:03:27fundamental to the processes going on in the iceberg.
0:03:28 > 0:03:32So Alun believed these plumes, or jacuzzis, played
0:03:32 > 0:03:36a part in the formation of icebergs and the team wanted to find out
0:03:36 > 0:03:39if they were connected to the hidden tunnels within the glacier.
0:03:44 > 0:03:47Richard is an imaging expert
0:03:47 > 0:03:50and joined the team to turn the underwater scan into a 3-D image.
0:03:51 > 0:03:54They hoped the 3-D image would have the answers
0:03:54 > 0:03:57they were looking for, so Richard wasted no time.
0:03:58 > 0:03:59What have we got, then?
0:03:59 > 0:04:02This is the side-scanning sonar results,
0:04:02 > 0:04:05but you've transformed them with some software into something...
0:04:05 > 0:04:07Yeah, that's right, yeah.
0:04:07 > 0:04:10I mean, if I put that into 3-D, you can start to see, now...
0:04:10 > 0:04:12So that's just the seafloor, no ice?
0:04:12 > 0:04:14That's just the seafloor we're looking at.
0:04:14 > 0:04:17We can put the ice back into that and there you can see the ice
0:04:17 > 0:04:21stretching from the north side to the south side of the glacier.
0:04:21 > 0:04:23Look at that!
0:04:23 > 0:04:27But then round the corner, into that, I'm beaming a huge cave.
0:04:27 > 0:04:31And this on the south side, here, that's where the plume's coming from?
0:04:31 > 0:04:35Exactly. These places match where all that water is coming out.
0:04:37 > 0:04:40This was the first time this had been seen.
0:04:40 > 0:04:43The 3-D image clearly showed caves which were
0:04:43 > 0:04:47the mouths of the sideways tunnels coming from under the blue lakes,
0:04:47 > 0:04:52pumping out millions of litres of fresh meltwater into the sea.
0:04:52 > 0:04:55These tunnels are the source of the water for the jacuzzis that
0:04:55 > 0:04:57Chris Packham had spotted earlier.
0:04:57 > 0:05:02It shows that most of these tunnels come out at the base of the ice,
0:05:02 > 0:05:04but not all of them.
0:05:04 > 0:05:06Is that a cave in the face of the glacier, then?
0:05:06 > 0:05:09Yes, it is a hole or a cave,
0:05:09 > 0:05:11or at least a heavily-fractured zone, in there.
0:05:11 > 0:05:16That's coming up within the face and that's something very new.
0:05:16 > 0:05:19- What an astonishing view! - It's lovely, isn't it?
0:05:19 > 0:05:24You can really visualise the fact that this glacier front
0:05:24 > 0:05:28- is not just a big flat wall. - This, for me, is it.
0:05:28 > 0:05:32Our time on the Gambo has been very well spent. Look at that.
0:05:32 > 0:05:36These amazing results caused the team to come up with
0:05:36 > 0:05:39a new theory about how mega-bergs are made.
0:05:39 > 0:05:43Alun now believes that these plumes of water, or jacuzzis,
0:05:43 > 0:05:48melt the glacier front into horseshoe shapes that form bays,
0:05:48 > 0:05:52leaving massive headlands sticking out, which eventually break off.
0:05:53 > 0:05:56What we're seeing is massive headlands with towering
0:05:56 > 0:05:58ice above the water line.
0:05:59 > 0:06:02They're 100, 120 metres high in places
0:06:02 > 0:06:06and that's where we're getting the really big mega-bergs forming.
0:06:08 > 0:06:10There it is. After three weeks at the glacier,
0:06:10 > 0:06:13all the pieces of research now fit together.
0:06:13 > 0:06:16The meltwater from the blue lakes flowing through the moulins,
0:06:16 > 0:06:19the speed the glacier moves, the discovery of the undercut,
0:06:19 > 0:06:24the sea temperature, it all adds up to explain how bergs are born.
0:06:24 > 0:06:27That's right, and the 3-D pictures are amazing, aren't they?
0:06:27 > 0:06:30It's fantastic to be able to see these huge tunnels emerge,
0:06:30 > 0:06:33carry all that water to the sea.
0:06:33 > 0:06:36It was an incredible few weeks, but I think we should leave it up
0:06:36 > 0:06:40to our friend, the physicist Helen Czerski, to sum it all up.
0:06:40 > 0:06:44We've seen that huge amounts of meltwater are produced at the surface
0:06:44 > 0:06:49and they percolate down into the ice through moulins and crevasses.
0:06:49 > 0:06:52And one theory was that all that water flowed down to the bedrock
0:06:52 > 0:06:54and underneath the ice,
0:06:54 > 0:06:58lubricating the movement of the glacier as it surges forward.
0:06:58 > 0:07:02There's a new theory that water could be taking a different route
0:07:02 > 0:07:06through a small number of huge tunnels, and that helps melt
0:07:06 > 0:07:11away the ice where the tunnels have formed and so we get these bays.
0:07:11 > 0:07:13And in between the bays, there are headlands,
0:07:13 > 0:07:18and those seem to be the bits that break off intact and that
0:07:18 > 0:07:25form the huge lumps of ice that carry on out to the open ocean as icebergs.
0:07:25 > 0:07:27Well, I couldn't have put that better myself,
0:07:27 > 0:07:29Chris, I completely understand, now.
0:07:29 > 0:07:32The formation of bays leaves these other bits sticking out
0:07:32 > 0:07:35and eventually they break off and, hey presto,
0:07:35 > 0:07:36you've got yourself an iceberg.
0:07:36 > 0:07:39That's it, and they can be absolutely enormous,
0:07:39 > 0:07:41as you're going to see in a little bit.
0:07:41 > 0:07:43I suppose the thing is, you never actually know
0:07:43 > 0:07:46when an iceberg's going to form or carve,
0:07:46 > 0:07:49- so capturing it on camera must be really difficult.- Completely.
0:07:49 > 0:07:53Every day, we'd been hoping that we'd see a mega-berg carve,
0:07:53 > 0:07:54but we hadn't.
0:07:54 > 0:07:57Then, on our last day, just as we were packing for the move,
0:07:57 > 0:08:01Store Glacier decided to give us an incredible leaving present.
0:08:01 > 0:08:03And what a sight. Feast your eyes on this.
0:08:05 > 0:08:08Just as we were packing up, it happened...
0:08:08 > 0:08:11A classic demonstration of the effect
0:08:11 > 0:08:13of everything we'd discovered.
0:08:13 > 0:08:14- Wow!- Oh-ho-ho!
0:08:16 > 0:08:19- Oh, wow, look.- That is massive.
0:08:21 > 0:08:22Just as Alun had predicted,
0:08:22 > 0:08:25a whole headland started collapsing.
0:08:25 > 0:08:26It was the most enormous
0:08:26 > 0:08:28and most violent carving,
0:08:28 > 0:08:29or birth of a berg,
0:08:29 > 0:08:31we'd seen so far.
0:08:33 > 0:08:35Just phenomenal.
0:08:35 > 0:08:37This was a mega-berg
0:08:37 > 0:08:39to end all mega-bergs.
0:08:44 > 0:08:47That iceberg is a kilometre across.
0:08:47 > 0:08:50As the mighty berg rose from the water,
0:08:50 > 0:08:53you could see a line in the ice toward the left-hand end.
0:08:53 > 0:08:57The line separated the ice that was above the water on the left
0:08:57 > 0:09:02and the massive amount of ice that was below the water on the right.
0:09:02 > 0:09:04Oh-ho-ho!
0:09:04 > 0:09:07So there's a wave of, kind of, fractures going along the top
0:09:07 > 0:09:11end of it, so all the stuff that was the cliff is now just crumbling.
0:09:15 > 0:09:18And that's the first time the water in that has seen the light of day
0:09:18 > 0:09:20for thousands of years.
0:09:23 > 0:09:26We talk about glaciers as, like, a metaphor for slowness and tedium,
0:09:26 > 0:09:29but this thing is completely alive.
0:09:32 > 0:09:35That is one of the biggest bits of natural destruction
0:09:35 > 0:09:37I've ever seen in my life.
0:09:37 > 0:09:39It was fantastic.
0:09:41 > 0:09:45The glacier had given us an amazing leaving present, a mega-berg.
0:09:46 > 0:09:48All of the things the team had learnt
0:09:48 > 0:09:52so far was demonstrated before their very eyes.
0:09:53 > 0:09:57And now that I've seen all of what's going on to produce just one
0:09:57 > 0:10:00iceberg, all of the things that happen behind the scenes,
0:10:00 > 0:10:05if you like, watching an iceberg carve is a much richer event.
0:10:07 > 0:10:10We've been trying to measure these things in St Paul's Cathedrals,
0:10:10 > 0:10:12but I wouldn't know where to start.
0:10:14 > 0:10:17I wonder where that iceberg will end up. Where's it going to drift to?
0:10:17 > 0:10:18Where's it going to finally melt?
0:10:18 > 0:10:21Where's it going to be when the last little piece,
0:10:21 > 0:10:24the size of a golf ball,
0:10:24 > 0:10:26melts and becomes part of the ocean?
0:10:28 > 0:10:30Makes you wonder, doesn't it?
0:10:30 > 0:10:34Wow! I just don't know what to say, that was so incredible!
0:10:34 > 0:10:36It was indeed an awesome sight.
0:10:36 > 0:10:38To be honest, it was amazing being there at the time,
0:10:38 > 0:10:40but these camera shots are astonishing.
0:10:40 > 0:10:43I think they really capture the moment brilliantly.
0:10:43 > 0:10:45You know what I'm going to ask, don't you?
0:10:45 > 0:10:47I think I can guess. Could it be that you want to see it again?
0:10:47 > 0:10:49Who wouldn't?
0:10:49 > 0:10:51Not many people wouldn't, I don't think,
0:10:51 > 0:10:54and I'm not one of those that wouldn't want to...
0:10:54 > 0:10:56- Do you want to see it or not?- Yes.
0:10:56 > 0:10:58Run the VT, guys!
0:10:59 > 0:11:02That was absolutely amazing.
0:11:05 > 0:11:07It was a massive amount of ice,
0:11:07 > 0:11:10creating an absolutely enormous mega-berg.
0:11:13 > 0:11:17I loved to see it when it just reared up out of the water
0:11:17 > 0:11:19and created such gigantic waves.
0:11:20 > 0:11:22- Wow.- Oh-ho-ho!
0:11:24 > 0:11:26Really incredible.
0:11:27 > 0:11:30That was even better the second time around, Chris,
0:11:30 > 0:11:32that was absolutely awesome!
0:11:32 > 0:11:34It was awesome, I was genuinely in awe of nature
0:11:34 > 0:11:36and so was everyone else watching.
0:11:36 > 0:11:38What a brilliant leaving gift from Store Glacier.
0:11:38 > 0:11:41It's a shame you didn't have much time to hang around
0:11:41 > 0:11:44and appreciate it, but I guess you all needed to finish packing
0:11:44 > 0:11:47and head off to the mega-berg to carry out more icy experiments.
0:11:47 > 0:11:49Right, but packing wasn't quick,
0:11:49 > 0:11:53it was a massive logistical operation to move everything.
0:11:53 > 0:11:55We had tonnes of equipment to take
0:11:55 > 0:11:57from the glacier and get to the iceberg.
0:11:57 > 0:11:59So did you need to find an iceberg
0:11:59 > 0:12:02big enough to land a jumbo jet on to get all the kit there?
0:12:02 > 0:12:04No, Xand, we didn't take a jumbo jet,
0:12:04 > 0:12:05but it was still a big, big job.
0:12:05 > 0:12:09And before we go, I thought I'd give you a little teaser,
0:12:09 > 0:12:11a little flavour of what lies in store next time,
0:12:11 > 0:12:13when we get to the iceberg.
0:12:13 > 0:12:15Nice one, Chris. I'm looking forward to this.
0:12:18 > 0:12:22Next, we headed for an absolutely gigantic island of ice,
0:12:22 > 0:12:25an enormous arctic mega-berg.
0:12:25 > 0:12:27A huge piece of ice the size of a city,
0:12:27 > 0:12:30an absolute wonder of the natural world.
0:12:34 > 0:12:36This is super, super hard ice.
0:12:37 > 0:12:41The science team were determined to discover what happens
0:12:41 > 0:12:43- to an iceberg out at sea... - Beautiful.
0:12:44 > 0:12:48..and to understand the forces that cause it, ultimately,
0:12:48 > 0:12:49to melt and disappear.
0:12:50 > 0:12:52And it looks entirely without life,
0:12:52 > 0:12:57an inhospitable lump of freezing freshwater floating in seawater.
0:12:58 > 0:13:01It's just a stunning sight.
0:13:01 > 0:13:05I've never seen a single piece of ice that is this big.
0:13:05 > 0:13:08It's an absolutely amazing sight.
0:13:08 > 0:13:12For two years, this berg had been the single biggest object
0:13:12 > 0:13:14afloat in the northern seas.
0:13:14 > 0:13:16It even had a name, the Petermann Iceberg.
0:13:18 > 0:13:20Whilst on the iceberg,
0:13:20 > 0:13:22we had huge challenges to overcome...
0:13:22 > 0:13:23It's falling, here.
0:13:25 > 0:13:28..from facing the biggest land predator
0:13:28 > 0:13:33to surviving in one of the most unpredictable environments on Earth.
0:13:35 > 0:13:37MACHINE BLEEPS
0:13:39 > 0:13:42Whoa, that just looks unbelievably exciting. I can't wait!
0:13:42 > 0:13:45- Well, you're going to have to wait, Xand.- OK, then, I will wait.
0:13:45 > 0:13:47I want to see what happens on that berg.
0:13:47 > 0:13:51OK, well, make sure you come back to see things that will Blow Your Mind.