00:00So, in the end, will the sun be to blame for destroying our planet?
00:04Or how about a huge meteorite?
00:07Or some kind of disease?
00:10Probably not.
00:12It seems that life will disappear for a very unexpected reason.
00:16Humans, animals, insects, fish, and most microbes will be wiped off the face of the Earth because of oxygen.
00:23Or, more precisely, because of its absence.
00:27Recent research has shown that the number of freshwater reservoirs, with very low or no oxygen levels in coastal areas, is increasing worldwide.
00:36Over the past 65 years, four times more oxygen-deficient waters have appeared in the world's oceans.
00:42What does it all mean?
00:44It's likely that life on Earth will vanish much sooner than the sun's energies dries up all the oceans.
00:50The end is likely to come in a little more than 1 billion years.
00:54But this doesn't mean that the planet will disappear too.
00:58The period when Earth is filled with oxygen will make up just about 20-30% of the total lifespan of the planet.
01:06So, we're just temporary guests here.
01:08Just think how long that is.
01:101 billion years.
01:11The first Homo sapiens appeared only about 300,000 years ago.
01:16That is, the entire history of humanity occupies less than a half a million years.
01:21So, relax.
01:22A billion years won't pass very fast.
01:25By that time, humans won't be on Earth anymore.
01:28We might master space travel and find a new planet in the vast depths of space.
01:33But why can we lose air?
01:35As the sun heats up, the planet gets warmer and warmer.
01:38And this heat breaks down carbon dioxide, the gas which is necessary for all plants to photosynthesize.
01:45Without carbon dioxide, they can't produce oxygen.
01:48With a drop in carbon dioxide levels, the methane content will increase.
01:53And this gas is quite harmful to us.
01:55Now, this all sounds logical, but this is a secondary reason for the lack of oxygen.
02:01The real problem is something else entirely.
02:04As the sun becomes brighter, it will begin to heat rocks on Earth, such as granite and basalt.
02:10These rocks will start to break down faster.
02:12When they collapse, they take carbon dioxide from the air, which warms our planet.
02:17If there's less carbon dioxide in the air, Earth should become colder.
02:22But there's a problem.
02:23The sun will shine more, and its heat will outweigh this cooling effect.
02:27So even if rocks take away carbon dioxide, the sun will blaze so much that Earth will still become extremely hot.
02:34Next, when the sun shines more intensely, it, along with other natural factors, contributes to the breakdown of granite and basalt.
02:43These rocks mix with carbon dioxide and water to make carbonates, which go deep into the Earth.
02:49This takes carbon dioxide out of the air, which means plants can't make as much oxygen because they need carbon dioxide to do that.
02:57Besides, volcanoes release gases, which also reduce the amount of oxygen in the air.
03:02So the sun, by destroying rocks, affects what happens inside Earth and controls how much oxygen there will be in the air.
03:11In about 1 billion years, the sun will become so bright that no rocks will be able to save Earth from its heat.
03:18And the escaping gases will halt photosynthesis and oxygen production.
03:23And then, our planet will return to the state it was in about 2.4 billion years ago.
03:29To the time when the Great Oxidation Event began.
03:32And this event was much more important than, say, the first Olympic Games or the appearance of humans on the planet.
03:39Billions of years ago, there was almost no oxygen on Earth.
03:43Instead, there was a soup of gases, such as nitrogen, ammonia, methane, carbon dioxide, and others.
03:50Yes, we have these gases in the atmosphere today, but there used to be a lot more of them in the past.
03:56It was difficult for any form of life to originate in such conditions.
04:01But after some struggle, it succeeded.
04:04At first, Earth was inhabited by the simplest bacteria, including cyanobacteria.
04:09They learned how to make oxygen using sunlight, water, and carbon dioxide.
04:14These bacteria worked for millions and billions of years, and made so much oxygen that it began to accumulate in the air.
04:21This was what we now call the Great Oxidation Event.
04:25It was like a great celebration of life, because with oxygen, new living beings could appear.
04:31But, by the way, cyanobacteria didn't learn photosynthesis, because they were like,
04:36Oh, let's make oxygen, it's so cool.
04:39No, oxygen was just a byproduct.
04:42Cyanobacteria wanted only one thing, to get as much energy as possible.
04:46And for this, they learned photosynthesis.
04:49It helped them store energy using sunlight.
04:52They used special pigments to absorb light, and the result of this process was the release of oxygen.
04:58This had been going on for hundreds of millions of years.
05:01And then, at some point, they made too much oxygen.
05:04This oxygen started to spoil other gases that had been there before.
05:08For example, it ate a lot of methane.
05:11Because of this, Earth cooled down a bit, and the Ice Age began.
05:15But that's another story.
05:17In short, in a billion years, we risk going back to that difficult time.
05:21But let's hope that we'll manage to move to another planet on our spaceships, or come up with some other solution.
05:28And what'll happen to our home planet next?
05:31Will new life be able to originate there without so much oxygen?
05:35Well, it's possible, but it'll be much more difficult.
05:37This will require another source of energy besides the sun.
05:42It can be, for example, hydrothermal vents.
05:45And, by the way, there are ecosystems on Earth that use this type of energy.
05:50You can find one of them in the Movae cave in Romania.
05:53Imagine a place where there's little oxygen.
05:56It's dark.
05:57The sun's rays don't reach there.
05:59Over millions of years of evolution, a unique and slightly creepy life has developed in this cave.
06:05It was first discovered in 1986, and scientists are still exploring this place.
06:10The entrance to the cave is just a small hole in the ground.
06:14A narrow tunnel goes deep underground.
06:17Inside the cave, the air is filled with hydrogen sulfide and carbon dioxide.
06:21And there's half as much oxygen there as on the surface.
06:25A human can't stay there without a special mask.
06:28But for local forms of life, this is home.
06:31And they feel great there.
06:32There are several dozen species living in the cave, and many of them aren't found anywhere else on Earth.
06:39Here you can see strange little monsters.
06:42White snails, white spiders, centipedes with long whiskers, transparent shrimp, and even unknown species of leeches.
06:51Since there's no light in the cave, all these creatures don't need eyes.
06:55They're blind.
06:56But they have long sensitive antennae and paws that allows them to navigate in the space.
07:02They also have no colored pigment.
07:04So all these bugs and spiders are either white or transparent.
07:08But if there's so little oxygen there, and nobody does photosynthesis, then how does all this life survive?
07:15It's all thanks to the unique bacteria autotrophs.
07:19They absorb carbon dioxide and produce nutrients.
07:22These bacteria are food for other organisms.
07:25And those, in turn, become food for larger creatures.
07:28So, a whole food chain has been built in the cave, which provides all the inhabitants with food.
07:35Evolution has created a unique ecosystem that exists separately from the rest of the world.
07:40It's like a small universe that has developed according to its own rules.
07:44However, this universe is not expanding, because all living beings here can't live away from hydrothermal vents and autotrophs.
07:52Otherwise, where would they get their energy from?
07:56But let's imagine that the sun cools down, almost all the oxygen disappears, and the entire planet gets covered with hydrothermal vents.
08:05It's dark, and the air is filled with methane, CO2, and other substances.
08:10And somehow, life begins.
08:12Even people appear at one point.
08:15What would they look like?
08:16Pale, thin, and blind creatures with very long arms that help them navigate in space.
08:21They have pets, large centipedes, or cockroaches that move silently on the ground.
08:28People are also quiet because they don't have lungs filled with air to scream.
08:33There's silence in the world.
08:35People communicate through touch.
08:37No one travels.
08:38Everyone lives separately next to their hydrothermal source.
08:41The whole world has turned into a horror movie in a billion years.
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