0:00:02 > 0:00:03It's a tornado!
0:00:04 > 0:00:06Look at that!
0:00:11 > 0:00:15Our planet is home to some spectacular natural wonders.
0:00:17 > 0:00:19THUNDERCLAP
0:00:19 > 0:00:25Yet exactly how and why they form is still a mystery.
0:00:27 > 0:00:31But now, new camera technologies are revealing
0:00:31 > 0:00:34their inner workings in stunning detail.
0:00:38 > 0:00:41My name is Dr Helen Czerski
0:00:41 > 0:00:44and I'll be looking at how these extraordinary images
0:00:44 > 0:00:49are transforming our understanding of the natural world.
0:00:53 > 0:00:54In this programme,
0:00:54 > 0:00:59we reveal the latest scientific insights into icebergs.
0:01:03 > 0:01:05Ever since one sank the Titanic,
0:01:05 > 0:01:09icebergs have been seen as a menace, a hazard on the polar seas.
0:01:09 > 0:01:13But each iceberg is also a beautiful ice sculpture,
0:01:13 > 0:01:17with a fascinating history and future all of its own.
0:01:20 > 0:01:22Now, side scanning sonar is unveiling
0:01:22 > 0:01:26what happens at the edge of glaciers, where icebergs are born.
0:01:28 > 0:01:32Satellite images are showing that icebergs create hot spots
0:01:32 > 0:01:34for life in the polar seas.
0:01:35 > 0:01:38And eyewitness pictures are giving us
0:01:38 > 0:01:42a unique glimpse of how icebergs transform over time.
0:01:45 > 0:01:49And all these new findings also give us vital clues
0:01:49 > 0:01:51about our changing planet.
0:02:17 > 0:02:19- Wow!- Oh!
0:02:19 > 0:02:23I'm in Greenland to witness one of nature's most violent
0:02:23 > 0:02:27and dramatic events - the birth of an iceberg.
0:02:28 > 0:02:30Just phenomenal.
0:02:30 > 0:02:33Catching on camera 500 million tons of ice
0:02:33 > 0:02:38breaking away into the sea, it's an awe-inspiring sight.
0:02:47 > 0:02:49Oh, oh!
0:02:49 > 0:02:53There's a wave of kind of fractures going along the top end of it,
0:02:53 > 0:02:57so all the stuff that WAS the cliff is now just crumbling.
0:03:00 > 0:03:02And that's the first time the water in that
0:03:02 > 0:03:05has seen the light of day for thousands of years.
0:03:08 > 0:03:10In recent years, the number of icebergs
0:03:10 > 0:03:14calving from the world's glaciers has been increasing steadily.
0:03:17 > 0:03:20Which is why it's never been more important
0:03:20 > 0:03:24for scientists to study the birth and life cycle of an iceberg.
0:03:33 > 0:03:38Research has shown that 95% of all icebergs in the northern hemisphere
0:03:38 > 0:03:40come from one place - Greenland.
0:03:46 > 0:03:51It's an island covered by a giant ice sheet, up to 3km thick.
0:03:59 > 0:04:03Greenland's many glaciers transport these vast masses of ice
0:04:03 > 0:04:09towards the sea, where they pump out 20,000 icebergs every year.
0:04:10 > 0:04:13Icebergs aren't just broken chunks of sea ice.
0:04:13 > 0:04:16They begin their life in a glacier
0:04:16 > 0:04:18and are made from frozen fresh water.
0:04:22 > 0:04:24But Greenland's glaciers are dwarfed
0:04:24 > 0:04:27by those on the other side of our planet.
0:04:27 > 0:04:3390% of the world's freshwater ice can be found here, in Antarctica.
0:04:35 > 0:04:39And the glaciers here are where the very biggest icebergs are born.
0:04:42 > 0:04:45The largest ice stream in the Western Antarctic
0:04:45 > 0:04:46is Pine Island Glacier.
0:04:48 > 0:04:52In 2011, NASA scientists noticed a strange feature
0:04:52 > 0:04:54across the top of it and here it is.
0:04:54 > 0:04:57There's a dark line running all the way through the ice.
0:04:57 > 0:05:00And when they went to have a look in a research plane,
0:05:00 > 0:05:02they flew across the feature,
0:05:02 > 0:05:04taking a photograph every two seconds,
0:05:04 > 0:05:07and they stitched together this stunning video.
0:05:07 > 0:05:11And you can see that that dark line is actually an ice canyon.
0:05:11 > 0:05:15It's 50 metres deep, 70 metres across,
0:05:15 > 0:05:19and it zigzags across the ice for 30km.
0:05:21 > 0:05:24Scientists knew that such a wide crack wouldn't be able
0:05:24 > 0:05:27to hold the ice sheet together for very long
0:05:27 > 0:05:33and in 2013, 720 square kilometres of ice broke off...
0:05:35 > 0:05:37..creating a gigantic iceberg.
0:05:40 > 0:05:43You can see it really clearly here on this satellite sequence.
0:05:43 > 0:05:46As time goes on into 2014,
0:05:46 > 0:05:51it breaks away and the entire iceberg drifts out into the sea.
0:05:51 > 0:05:54It's about 500 metres thick, at this point,
0:05:54 > 0:05:57about 30km long and 18km wide.
0:05:57 > 0:06:01It's gigantic and it became known as iceberg B31.
0:06:07 > 0:06:11Three years on, B31 is still floating in the Southern Ocean,
0:06:11 > 0:06:12around Antarctica.
0:06:16 > 0:06:20And scientists are monitoring it every step of the way.
0:06:24 > 0:06:28They're concerned it could travel as far as the South Atlantic,
0:06:28 > 0:06:30posing a threat to shipping lanes.
0:06:33 > 0:06:34Like any iceberg,
0:06:34 > 0:06:38what you see above the water is only a fraction of what lurks beneath.
0:06:41 > 0:06:44One of the reasons that icebergs are so dangerous
0:06:44 > 0:06:47is that most of an iceberg is actually below the waterline.
0:06:47 > 0:06:51You can see, if I put a big cube of ice into the water,
0:06:51 > 0:06:54most of it sits below.
0:06:55 > 0:06:59You can see that there's only this tiny bit here, the top 10%,
0:06:59 > 0:07:03which is above the waterline. Everything else is down below.
0:07:03 > 0:07:04And the reason for this
0:07:04 > 0:07:07is all to do with the molecular structure of ice.
0:07:11 > 0:07:14The secret lies at the heart of an ice crystal.
0:07:15 > 0:07:18It's the way the ice crystal forms which is the key
0:07:18 > 0:07:20to why it floats the way it does.
0:07:26 > 0:07:29Water molecules are held together by loose bonds
0:07:29 > 0:07:32which are constantly breaking and reattaching.
0:07:33 > 0:07:37When the temperature drops to zero, these bonds begin to hold,
0:07:37 > 0:07:39creating a hexagonal lattice.
0:07:43 > 0:07:46In the lattice, the bonds hold the molecules further apart.
0:07:48 > 0:07:52It's this opening out that makes ice less dense than liquid water.
0:07:53 > 0:07:55But only just.
0:07:59 > 0:08:01The density of the water in this tank
0:08:01 > 0:08:04is about 1,000 kilograms per cubic metre.
0:08:04 > 0:08:06But the density of the ice is less,
0:08:06 > 0:08:09it's only about 920 kilograms per cubic metre.
0:08:09 > 0:08:13And that's because when the ice froze, it expanded,
0:08:13 > 0:08:15so the ice takes up more space.
0:08:15 > 0:08:18If this ice cube was to melt completely,
0:08:18 > 0:08:21it would only take up exactly the volume of water
0:08:21 > 0:08:23that is below the waterline.
0:08:23 > 0:08:27And so, all that bit above, that's how much the ice has expanded by.
0:08:29 > 0:08:32But it's the 90% of an iceberg below the ocean surface
0:08:32 > 0:08:34that worries mariners most.
0:08:37 > 0:08:41Since the sinking of the Titanic in 1912,
0:08:41 > 0:08:43icebergs have been a major concern for shipping.
0:08:45 > 0:08:47- RECORDED FOOTAGE:- 'Drifting down from the north,
0:08:47 > 0:08:48'after breaking away from a glacier,
0:08:48 > 0:08:51'the icebergs making their way towards the shipping lanes,
0:08:51 > 0:08:53'become a grave danger to navigation.'
0:08:54 > 0:08:58The Titanic collided with an iceberg in Iceberg Alley...
0:09:00 > 0:09:03..a now notorious stretch of the North Atlantic,
0:09:03 > 0:09:05that sees a high number of icebergs.
0:09:07 > 0:09:09'There seems to be plenty of ice about.
0:09:09 > 0:09:11'Maybe that's had an effect on our weather over here.
0:09:11 > 0:09:12'It felt like it anyway.'
0:09:14 > 0:09:17To ensure safe passage through the area,
0:09:17 > 0:09:19the International Ice Patrol was set up.
0:09:22 > 0:09:26It's purpose? To track icebergs and warn ships.
0:09:26 > 0:09:29'Never mind how she got there. She WAS there.
0:09:29 > 0:09:32'Something had to be done right away.
0:09:32 > 0:09:36In its early years, the Ice Patrol didn't just track icebergs...
0:09:36 > 0:09:39EXPLOSION
0:09:39 > 0:09:41..they tried to destroy them.
0:09:41 > 0:09:43EXPLOSIONS
0:09:44 > 0:09:47But the experiments proved unsuccessful
0:09:47 > 0:09:50and the Ice Patrol eventually abandoned the project.
0:09:57 > 0:10:00Today, the Ice Patrol still monitors the North Atlantic
0:10:00 > 0:10:03and warns mariners of dangerous icebergs.
0:10:11 > 0:10:14Icebergs may be a threat for some
0:10:14 > 0:10:18but, for others, they're veritable treasure troves.
0:10:18 > 0:10:22In fact, rather than being inert lumps of ice...
0:10:23 > 0:10:27..new research shows that icebergs can transform the oceans.
0:10:35 > 0:10:38Jemma Wadham collects samples from the bottom of glaciers
0:10:38 > 0:10:40just before they turn into icebergs
0:10:40 > 0:10:44and brings them back to this low-temperature facility
0:10:44 > 0:10:46here, at the University of Bristol.
0:10:49 > 0:10:52So, what we've got here is a large chunk of ice
0:10:52 > 0:10:55that we've chain sawed out from the bottom of an ice sheet.
0:10:55 > 0:10:56And you can see, very clearly,
0:10:56 > 0:11:00there's a very thick band of sediment through the middle
0:11:00 > 0:11:03and that sediment will then eventually end up in icebergs
0:11:03 > 0:11:05which melt into the ocean.
0:11:05 > 0:11:08The sediment is the really interesting bit.
0:11:11 > 0:11:15Jemma wants to know which elements are present in the sediment layer.
0:11:17 > 0:11:20To analyse it, she first needs to prepare the sample.
0:11:24 > 0:11:28When she gets the results, they reveal something extraordinary.
0:11:32 > 0:11:36We can see, here, a really nice well-defined bump.
0:11:36 > 0:11:40And that bump indicates the presence of iron in our ice samples,
0:11:40 > 0:11:41which is really quite astonishing
0:11:41 > 0:11:43because you might look at an iceberg sometimes
0:11:43 > 0:11:45and think, "There's nothing in it",
0:11:45 > 0:11:47but, actually, there's quite a lot of iron.
0:11:51 > 0:11:55Iron is a key nutrient for life in the oceans.
0:11:57 > 0:12:01But it can't be used by marine life in all of its forms.
0:12:03 > 0:12:06The cool thing about icebergs is because they freeze this sediment
0:12:06 > 0:12:11into their underbellies, that freezing process preserves the iron.
0:12:12 > 0:12:15And as the icebergs move out into the ocean, they melt
0:12:15 > 0:12:20and, as they do, that sediment drops out of the iceberg into the ocean
0:12:20 > 0:12:23and releases that really nice, tasty iron.
0:12:25 > 0:12:28Jemma's research shows that ice can preserve the iron
0:12:28 > 0:12:30for thousands of years.
0:12:31 > 0:12:33And when an iceberg melts,
0:12:33 > 0:12:36it releases the iron into the surrounding oceans.
0:12:43 > 0:12:48There, it's used by phytoplankton - tiny floating plants.
0:12:49 > 0:12:53Each phytoplankton is scarcely bigger than a speck of dust.
0:12:55 > 0:13:00But, ultimately, they feed almost all the life in the sea...
0:13:01 > 0:13:05..from tiny fish to the giants of the ocean.
0:13:13 > 0:13:15This is a picture created by scientists
0:13:15 > 0:13:18at the University of Sheffield.
0:13:18 > 0:13:22It's based on satellite images of the ocean around Antarctica
0:13:22 > 0:13:26before and after several giant icebergs have passed by.
0:13:27 > 0:13:29So, in the wake of this iceberg,
0:13:29 > 0:13:32you can see this yellow colour and this red colour,
0:13:32 > 0:13:36just is a band in the wake of the iceberg and the surface ocean,
0:13:36 > 0:13:40and what that is is satellites, seeing from space,
0:13:40 > 0:13:43chlorophyll concentrations in the surface ocean.
0:13:43 > 0:13:46Now, chlorophyll is a pigment required for photosynthesis.
0:13:46 > 0:13:50The more chlorophyll, the more productive the phytoplankton are
0:13:50 > 0:13:53in the surface ocean, so we've got a really nice high productivity band
0:13:53 > 0:13:57of phytoplankton here, in the wake of the iceberg.
0:13:57 > 0:13:59And it's really fascinating
0:13:59 > 0:14:02that they can see the product of the ocean from space.
0:14:04 > 0:14:07The oceans flourish in the wake of melting icebergs.
0:14:21 > 0:14:24But on their journey through the seas,
0:14:24 > 0:14:26icebergs don't simply melt.
0:14:28 > 0:14:32They're also battered by collisions with other bergs
0:14:32 > 0:14:34and eroded by waves.
0:14:36 > 0:14:38And so, over time,
0:14:38 > 0:14:42icebergs can take on the most bizarre shapes and forms.
0:14:44 > 0:14:47And as they do so, they weaken.
0:14:54 > 0:14:56Just occasionally,
0:14:56 > 0:14:58there's an iceberg that looks completely different.
0:15:01 > 0:15:07This photo was taken by Alex Cornell on a trip to Antarctica in 2014.
0:15:07 > 0:15:11What we see here is the iceberg's underside.
0:15:13 > 0:15:15Through years of melting and eroding,
0:15:15 > 0:15:18its centre of gravity has shifted
0:15:18 > 0:15:21and it became so unstable that it rolled over.
0:15:21 > 0:15:25This is a spectacular image of a blue iceberg
0:15:25 > 0:15:28and its true colour. The ice really is this colour.
0:15:28 > 0:15:30It's not often that you see this,
0:15:30 > 0:15:34but what's happening is that light comes in from the atmosphere
0:15:34 > 0:15:37and, as it travels through the ice, very gradually,
0:15:37 > 0:15:39the red light and the green light get absorbed
0:15:39 > 0:15:42and by the time the light finds its way back out,
0:15:42 > 0:15:46the only colour left is blue. So, this is the true colour of ice.
0:15:46 > 0:15:49But that leaves a question, because normally,
0:15:49 > 0:15:52when we see icebergs, they look white like this one.
0:15:52 > 0:15:56And the reason is all to with a very small structure of the ice.
0:15:56 > 0:16:00So, if we look in, zoom in to a small piece of iceberg,
0:16:00 > 0:16:02you can see it's full of bubbles here,
0:16:02 > 0:16:04because, perhaps thousands of years ago,
0:16:04 > 0:16:08layers and layers of snow fell on top of a glacier
0:16:08 > 0:16:11until the ice and snow underneath was crushed together.
0:16:11 > 0:16:13So, the ice formed a solid block
0:16:13 > 0:16:16and the air was squeezed into separate little bubbles.
0:16:16 > 0:16:20So, when light hits an iceberg, white light comes in,
0:16:20 > 0:16:24it bounces off all these internal surfaces, all the bubbles,
0:16:24 > 0:16:26and white light comes back out.
0:16:26 > 0:16:27And that's why icebergs look white,
0:16:27 > 0:16:30even though the true colour of ice is blue.
0:16:32 > 0:16:35Deep in the ice, these air bubbles are gradually squeezed out,
0:16:35 > 0:16:39which is why the flipped iceberg looks blue.
0:16:42 > 0:16:46But as long as the bubbles are present, icebergs look white,
0:16:46 > 0:16:49as do glaciers and ice sheets.
0:16:51 > 0:16:53And because they're so bright,
0:16:53 > 0:16:56anything that isn't white, really stands out.
0:17:04 > 0:17:07That's how Peter Fretwell from the British Antarctic Survey
0:17:07 > 0:17:09made a surprising discovery.
0:17:12 > 0:17:15He was using satellite images to map the Antarctic coastline,
0:17:15 > 0:17:17when he spotted something unusual.
0:17:19 > 0:17:22We were mapping Antarctica and the coastline for our pilots,
0:17:22 > 0:17:24who need specific information on their maps.
0:17:24 > 0:17:29This is a satellite image of Antarctica
0:17:29 > 0:17:32and we can see here the coastline, this is the sea.
0:17:32 > 0:17:37In between the coastline and the sea, these white areas are sea ice.
0:17:37 > 0:17:40And there are some strange brown stains on it
0:17:40 > 0:17:43and we weren't sure what these brown stains were.
0:17:43 > 0:17:47The sea ice, which is frozen seawater, should be pristine.
0:17:47 > 0:17:49It should be pure white.
0:17:49 > 0:17:52When we zoomed in with the satellite imagery,
0:17:52 > 0:17:55it started to resolve itself as to what these were.
0:17:55 > 0:18:00We had brown areas and strange black areas as well there.
0:18:00 > 0:18:02And I put two and two together
0:18:02 > 0:18:05and realised that what we were looking here, with the satellites,
0:18:05 > 0:18:08wasn't just brown stains on the ice. It was actually penguins.
0:18:09 > 0:18:12The brown area is the guano,
0:18:12 > 0:18:17the stain that they leave on the ice from their droppings and their poo
0:18:17 > 0:18:20over the eight months or so that they inhabit this area.
0:18:22 > 0:18:26Peter had discovered an emperor penguin colony from space.
0:18:34 > 0:18:38At well over one metre, emperors are the tallest penguins on Earth.
0:18:41 > 0:18:45They live in large colonies and thrive in freezing conditions.
0:18:50 > 0:18:53And they breed in the middle of the harsh Antarctic winter,
0:18:53 > 0:18:56using frozen seawater as their breeding platform.
0:19:18 > 0:19:22But Peter's most recent satellite images show something unexpected.
0:19:24 > 0:19:28We found this colony, one where the penguins weren't on the sea ice.
0:19:28 > 0:19:31In this case, they were actually on an iceberg.
0:19:31 > 0:19:34Here, we can see a satellite image with a number of icebergs
0:19:34 > 0:19:37and one of them is almost totally covered
0:19:37 > 0:19:41in brown stain, guano, the penguin poo.
0:19:42 > 0:19:45It seems that there wasn't enough sea ice for the emperor penguins
0:19:45 > 0:19:48at the beginning of their breeding season.
0:19:48 > 0:19:51Early in the season here, the sea ice hasn't formed
0:19:51 > 0:19:54when the emperors have turned up at their breeding location.
0:19:54 > 0:19:56So, the emperors have been left with nowhere to go,
0:19:56 > 0:19:59but in this case, they've moved up onto the iceberg
0:19:59 > 0:20:02to give them somewhere to do their courtship
0:20:02 > 0:20:04and their mating and their breeding.
0:20:04 > 0:20:09Peter has since observed emperors on icebergs in other locations
0:20:09 > 0:20:12and it's something that's likely to become even more common
0:20:12 > 0:20:14as the climate changes.
0:20:14 > 0:20:17We've lost huge amounts of sea ice in the Arctic
0:20:17 > 0:20:18as the climate's warmed.
0:20:18 > 0:20:21And all of the predictions and the models suggest
0:20:21 > 0:20:22that Antarctica will go the same way
0:20:22 > 0:20:25and that we could lose lots of sea ice in Antarctica,
0:20:25 > 0:20:27which will be terrible for the emperor penguins.
0:20:27 > 0:20:32But having this adaptation, to be able to move onto icebergs
0:20:32 > 0:20:34or, in some cases, up onto the ice shelf,
0:20:34 > 0:20:37will be critically important to be able to save
0:20:37 > 0:20:40some of those emperor penguin colonies from extinction.
0:20:49 > 0:20:52Climate change isn't just having an effect on sea ice.
0:20:55 > 0:20:57It's also affecting the world's glaciers
0:20:57 > 0:21:01that are pumping out more icebergs than ever before.
0:21:03 > 0:21:05To find out why this is happening,
0:21:05 > 0:21:08we need to go dangerously close to the glacier front.
0:21:11 > 0:21:14It's all in a day's work for Alun Hubbard
0:21:14 > 0:21:16from Aberystwyth University.
0:21:16 > 0:21:20Could you go up front and just tell me left or right, please?
0:21:23 > 0:21:25On board the research yacht Gambo,
0:21:25 > 0:21:29he's trying to map the front of Greenland's Store Glacier.
0:21:33 > 0:21:36Alun uses a powerful tool - side scanning sonar.
0:21:36 > 0:21:40It reveals the hidden part of a glacier that's under water.
0:21:41 > 0:21:43That's the actual equipment
0:21:43 > 0:21:46that sends out the sound wave, the acoustic wave,
0:21:46 > 0:21:49which bounces off the glacier and we pick it up.
0:21:49 > 0:21:51So, we, hopefully, will be able to scan
0:21:51 > 0:21:54the whole face of the glacier and its toe.
0:21:55 > 0:21:58To get a detailed picture,
0:21:58 > 0:22:00Gambo needs to go right up to the ice front,
0:22:00 > 0:22:02just where the icebergs calve.
0:22:05 > 0:22:10- We are 150 metres now. I would like to keep 200 or 300.- Yeah, OK.
0:22:11 > 0:22:14How are we for bergs there?
0:22:14 > 0:22:16Have to go a bit starboard, I think.
0:22:16 > 0:22:20It's the first attempt by any research team
0:22:20 > 0:22:25to image the entire underwater ice front of a glacier as big as this.
0:22:25 > 0:22:29But just then, the giant glacier reminds them of the risks.
0:22:33 > 0:22:36CREW MEMBERS SHOUT
0:23:06 > 0:23:09Back in the UK, Alun has had a chance
0:23:09 > 0:23:12to analyse the sonar images from Store Glacier.
0:23:14 > 0:23:17This is the result from the side scanning sonar.
0:23:17 > 0:23:22We've got the seabed here and this is the glacier front here.
0:23:22 > 0:23:25And it shows us that the glacier front is far from a plane
0:23:25 > 0:23:30or flat block surface. And this is 5km, so it's a big place.
0:23:30 > 0:23:34But what I love here is, all the way along here,
0:23:34 > 0:23:38we're getting very obvious undercuts at the base,
0:23:38 > 0:23:42where the ice is sitting on the sea floor.
0:23:43 > 0:23:46To find out why the glacier front is so undercut,
0:23:46 > 0:23:50Alun had to compare scans from several different days
0:23:50 > 0:23:53and when he analysed the data,
0:23:53 > 0:23:58he discovered that the glacier front is melting at an extraordinary rate.
0:23:58 > 0:24:01Here we get submarine melt rates
0:24:01 > 0:24:05in excess of four or five metres a day,
0:24:05 > 0:24:08which is pretty phenomenal when you think about it.
0:24:10 > 0:24:15So, that's actually four metres of ice flowing into that front
0:24:15 > 0:24:19every day and it's just being taken away, melted away.
0:24:19 > 0:24:24Where that is really focussing is at the base of the glacier
0:24:24 > 0:24:27and that's what's leading to these big undercuts
0:24:27 > 0:24:30that we're seeing in the front of the glaciers.
0:24:30 > 0:24:32It's this submarine melting
0:24:32 > 0:24:36that's causing the huge undercut at the bottom of Store Glacier.
0:24:36 > 0:24:39We've come to realise that submarine melting
0:24:39 > 0:24:44has a really important role to play, in terms of undercutting the glacier
0:24:44 > 0:24:48and preconditions the glacier to fail in particular places.
0:24:53 > 0:24:56The undercut makes the glacier above unstable,
0:24:56 > 0:24:59which is why so many icebergs are calving off it.
0:25:00 > 0:25:04And when the underside of an iceberg rises above the ocean's surface,
0:25:04 > 0:25:07you can see evidence of submarine melting.
0:25:08 > 0:25:12The grooves on this mega berg are caused by it.
0:25:14 > 0:25:16The fresh melt water from the base of the iceberg
0:25:16 > 0:25:20rushes to the surface because it's less dense than seawater.
0:25:22 > 0:25:26And it brings with it the warmer ocean water from the seabed,
0:25:26 > 0:25:29creating grooves in the ice as it rises up.
0:25:47 > 0:25:51Since the year 2000, the sea temperatures around Greenland
0:25:51 > 0:25:55have gone up by one degree, exacerbating submarine melting
0:25:55 > 0:25:58and the effect it has on iceberg production.
0:26:01 > 0:26:04But the melting doesn't just weaken the glacier.
0:26:04 > 0:26:07It leads to an overall loss of ice from the ice sheet.
0:26:10 > 0:26:12Climate change, without doubt,
0:26:12 > 0:26:15is happening in Greenland and affecting Greenland.
0:26:15 > 0:26:17The ice sheet used to be in balance with its climate
0:26:17 > 0:26:19just two decades ago.
0:26:19 > 0:26:23It's certainly not in balance with its climate at the moment.
0:26:26 > 0:26:28The Greenland ice sheet is losing
0:26:28 > 0:26:33around 300,000 million tons of ice per year
0:26:33 > 0:26:37that's not being replaced by snowfall in the middle,
0:26:37 > 0:26:38so it's losing that mass
0:26:38 > 0:26:41and that's going into a global sea level rise
0:26:41 > 0:26:43which is about a millimetre per year.
0:26:43 > 0:26:45So, Greenland's the largest contributor
0:26:45 > 0:26:47to global sea level rise -
0:26:47 > 0:26:50much greater than all of Antarctica put together.
0:26:54 > 0:26:58The Arctic and the Antarctic are covered in and shaped by ice.
0:26:58 > 0:27:01We see ice as harsh and unyielding,
0:27:01 > 0:27:04but these frozen places are particularly sensitive
0:27:04 > 0:27:06to warming temperatures.
0:27:06 > 0:27:08Although the polar regions are remote,
0:27:08 > 0:27:10they're an important part of the Earth's system,
0:27:10 > 0:27:13linked into all our lives,
0:27:13 > 0:27:17so what happens at the poles affects all of us, no matter where we live.
0:27:30 > 0:27:34In recent years, new camera technologies have allowed us
0:27:34 > 0:27:36to get closer to icebergs than ever before.
0:27:43 > 0:27:45We now have a much greater understanding
0:27:45 > 0:27:49of the complex processes that lead to the birth of an iceberg...
0:27:53 > 0:27:55..determine its life cycle...
0:27:59 > 0:28:03..and how it can transform the surrounding polar seas.
0:28:17 > 0:28:22And the study of icebergs is also giving us an important insight
0:28:22 > 0:28:25into how climate change is affecting our planet.