00:006.
00:01Dark patches on Greenland's ice sheet These dark patches on Greenland's ice sheet
00:04aren't just any old stains.
00:07Every summer, the ice, which is usually bright white, turns murky gray in certain areas.
00:13This so-called dark zone was a huge mystery for a long time, until some studies discovered
00:18that this weird transformation was connected to the odd appearance of red, green, and brown-colored
00:24algae.
00:25The scariest part is that this algae bloom keeps growing.
00:29The dark zone is getting darker, and terrifying microbes might start appearing.
00:34Now, the rest of the world should be concerned.
00:38The Greenland ice sheet is like a massive ice blanket that covers around 80% of the
00:43island.
00:44It's so thick that it holds about 8% of the world's freshwater ice.
00:48For most of the year, the ice looks like a giant untouched white sheet stretching over
00:53the land.
00:54But when summer rolls around and temperatures start to rise, things begin to change.
01:00The ice melts, revealing rocky areas along the coast.
01:02And as you move further inland, that once smooth white ice becomes darker.
01:08This is the dark zone, and it covers an area of around 248 miles in length and 62 miles
01:14at its widest point.
01:16This weird phenomenon happens basically for two reasons.
01:20The first one is black carbon.
01:23Just like dust that builds up on your bookshelf, the ice in Greenland has the same issue.
01:28The wind carries a mix of dust and soot to this icy area.
01:32But unlike your bookshelf, you can't just wipe it off with a cloth.
01:36In Greenland's case, this dirty mix settles on the ice and sticks around for thousands
01:41of years.
01:45So the dark zone is basically covered in a fine layer of dust that's built up over time.
01:51Back in 2014, researchers analyzed this dirty mix and found that the darker ice areas were
01:56filled with black carbon.
01:59This black carbon didn't just appear out of thin air.
02:02Well, actually, it sort of did.
02:05Scientists believe it mostly comes from smoke produced by wildfires in northern Canada and
02:09Alaska somewhere in the past.
02:12As you might guess, black carbon is black, which is why it makes the ice look darker.
02:20Now the second big reason for the Greenland ice sheet's summer makeover has to do with
02:24those algae we mentioned earlier.
02:27We're mostly talking about two types of it, the Anselonoma alaskana and the Anselonoma
02:33nordensholdii.
02:35Both of them love cold water regions.
02:38During winter, they stay in a dormant state deep within the ice.
02:42But when spring comes, they start to slowly migrate to the surface.
02:46By the time summer hits, they're ready to bloom and soak up nearly 24 hours of sunlight
02:51each day for photosynthesis and growth.
02:54Normally, these algae are green, but when exposed to sunlight, they turn brown as a
03:00natural way to protect themselves from harmful ultraviolet rays.
03:04And this color change is also what makes the ice in Greenland look darker.
03:12So far, this has been normal behavior.
03:14What's really alarming is that these algae blooms are getting bigger and bigger every
03:18year.
03:19This happens because they thrive on phosphorus, a nutrient that's plentiful out there and
03:24comes from a mineral called hydroxylapatite.
03:28This mineral is found in a type of rock that breaks down into tiny dust particles, which
03:33are then blown across the ice by the wind.
03:36As the climate gets warmer, the rocks dry out more, and stronger winds carry more dust.
03:42More dust means more phosphorus, leading to more algae growth.
03:47See?
03:48It is a cycle, and it keeps getting worse every year.
03:52Studying this is crucial to understanding why the dark zone keeps getting bigger.
03:57From the year 2000 to 2012, its size increased by 12%.
04:05But you might be wondering, why should we care?
04:08After all, it's just ice getting darker, right?
04:11Well, not exactly.
04:13Think about how you can't stand wearing black clothes on a hot sunny day.
04:17They soak up the heat and make you feel even hotter.
04:20That's because darker surfaces absorb more sunlight.
04:23The same thing happens to ice.
04:25Together, dust, black carbon, and algae blooms are responsible for about 70% of the variability
04:32in albedo on the Greenland ice sheet.
04:36Albedo is just a fancy word for how reflective a surface is.
04:40If you take two surfaces, one white and shiny, and the other dark and rough, the white one
04:45will reflect a lot of light and heat, giving it a high albedo.
04:50The dark one, on the other hand, will absorb more light and heat, so it has a low albedo.
04:58During the summer, the Greenland ice sheet experiences a reduction in albedo.
05:03This means the ice absorbs more sunlight, and when ice absorbs more sunlight, it melts
05:08faster than it should.
05:09This is why understanding what's happening in the dark zone is so important.
05:14It helps predict how quickly the Greenland ice sheet is melting and how it can affect
05:19the rest of the world.
05:23Greenland's ice sheet is the second largest in the world, covering an area about the size
05:28of all the land in the United States east of the Mississippi River, and its huge mass
05:33of ice averages a thickness of 1.4 miles.
05:38Unfortunately, the ice loss has skyrocketed.
05:41Back in the 1990s, Greenland was losing about 25 billion tons of ice per year.
05:47Now it's losing around 234 billion tons per year.
05:53That's nearly 10 times more ice melting away each year.
06:00According to NASA, if all of Greenland's ice sheet were to melt, it would increase
06:04global sea levels by about 24 feet.
06:08That could be catastrophic for coastal countries and cities around the world.
06:12The Netherlands could be submerged, the Bahamas could be almost completely wiped out, and
06:18many of the Philippines' islands would be at risk of disappearing.
06:22All of this may seem like a distant reality, and it is true that most scientists believe
06:28it would take several hundred or even thousands of years for the ice sheet to melt completely.
06:34But it is important to know that Greenland didn't always have this thick layer of
06:38ice.
06:40Very recently, researchers took a close look at some sediment from the bottom of a two-mile
06:44deep ice core extracted from the center of Greenland.
06:48They found that the soil had traces of willow wood, insect parts, fungi, and even poppy
06:54seeds.
06:55So these fossils are the first direct evidence that Greenland's ice sheet melted away
06:59in the recent geological past, around 400,000 years ago.
07:05At that time, Greenland was home to a green tundra landscape with insects and plants.
07:11This discovery is both fascinating and scary because it shows that the ice sheet collapsed
07:16before and might be more fragile than scientists originally thought.
07:23There is another concern, too.
07:25A recent research collected meltwater from different spots on the Greenland ice sheet
07:30and found that the water samples were packed with hundreds and thousands of microbes.
07:35The concern is that they could be released into the ocean in the future.
07:39And some studies already suggest that areas near where a lot of glacial meltwater flows
07:45have a higher risk of viruses jumping to new hosts, like from animals to humans.
07:52Even though experts believe the chance of a doomsday virus coming from the glaciers
07:56is very small, it's still not zero.
08:00The truth is, we don't know much about the thousands of microbial species living on the
08:05surface of the ice, and there is simply not enough data to fully understand how dangerous
08:11these organisms might be.
08:14All of this might sound concerning, but we shouldn't panic just yet.
08:18There's still a lot we don't understand about what is darkening the Greenland ice
08:22sheet.
08:23We still need more detailed measurements of the relative abundance of dust, algae, and
08:28black carbon, as well as a better understanding of how these potentially dangerous microbes
08:33could affect our lives.
08:35The more we learn, the better we can predict what's going to happen and how we can prepare
08:39for it.
08:41That's it for today!
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