Avez-vous entendu parler des volcans en Antarctique ? Il s'avère qu'ils pourraient potentiellement rendre la Terre inhabitable ! Les scientifiques découvrent que si ces volcans entraient en éruption, ils pourraient libérer des quantités massives de cendres et de gaz dans l'atmosphère, affectant considérablement le climat mondial. La glace qui les recouvre rend en fait les éruptions encore plus explosives. C'est assez fou de penser que le continent gelé pourrait contenir un pouvoir aussi dangereux, n'est-ce pas ? Animation créée par Sympa.
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FunTranscript
00:00The largest volcanic region on Earth is neither in Africa nor in Japan, but under the ice of Antarctica, scientists have discovered 138 volcanoes in its western part, and if they ever erupt, you will surely notice it.
00:13They could melt huge amounts of ice that would spill into the ocean, increase the level and make our planet uninhabitable for humans.
00:22But before you pack your bags and fly off to another planet, listen to me.
00:26Currently, only two of Antarctica's volcanoes are officially classified as active, and it would take a series of eruptions, decade after decade, for them to have a serious impact on the whole world.
00:39Mount Erebus, one of these two volcanoes currently active, proudly bears the title of the most austral active volcano in the world.
00:47It has been continuously erupting since at least 1972. It emits gasses and vapors, and sometimes, it even expels rocks. Scientists call this strombolian eruptions.
00:59One of its most impressive characteristics is a lava lake, located in one of its summit craters, with fusion materials at the surface.
01:08Such lakes are quite rare, because certain conditions are necessary for their surface to never freeze.
01:14The second active volcano is the Island of Disappointment, a mass of land in the shape of an iron horse.
01:18It is the caldeira of an active volcano that erupted for the last time more than 50 years ago.
01:23Scientists who monitor it say that it should not wake up immediately.
01:27Antarctica is also the theater of regular fumaroles. It is an emanation of gases and volcanic vapors.
01:33In adequate conditions, crevasses can expel enough material to erect ice towers 3 meters high.
01:41Scientists monitor the volcanoes of Antarctica with seismometers that start working when the earth starts to tremble due to volcanic activity.
01:50Sometimes, they also use more complex technologies, but the operations are always difficult due to the distance of this polar region and the means to get there.
02:01This is why no one can predict when one of the volcanoes of the continent, currently asleep, will erupt.
02:07We could know what such an awakening would look like if we analyzed what happened nearly 20,000 years ago.
02:13But do we?
02:15One of the volcanoes asleep in Antarctica, Mount Takahe, once experienced a series of eruptions and emitted a good amount of halogen rich in ozone.
02:25Some scientists say that these events have warmed the southern hemisphere.
02:30Glaciers would have started to melt, and this would have contributed to the end of the last glacial era.
02:37For these events to repeat, a series of eruptions with halogen emissions from one or more volcanoes above the ice would be necessary.
02:47It is a unlikely scenario, but as it has already happened in the past, it is not completely impossible.
02:54As for the volcanoes hidden under a thick layer of ice, we think that their gas would have a hard time reaching the atmosphere.
03:00However, they would be powerful enough to melt huge caverns and produce large amounts of meltwater.
03:08The Antarctic glacier is wet and not attached to its base.
03:13This meltwater would act as a lubricant and would quickly move the ice that covers it.
03:19The volume of water that a volcano of this size could produce is nothing compared to the volume of ice that overflows it.
03:26Thus, a single eruption would not make a difference.
03:30However, with several eruptions of volcanoes located near or under the great ice currents of Western Antarctica, it would be another story.
03:40These ice currents are rivers that transport a large part of Antarctica's water to the ocean.
03:46If they changed their speed and brought unusual amounts of water into the ocean, their level would rise.
03:52As the ice became thinner and thinner, there would be more and more eruptions.
03:57Scientists call this a packing effect.
04:00A similar phenomenon occurred in Iceland.
04:03The number of volcanic eruptions increased when the glaciers began to recede at the end of the last glacial period.
04:11For massive changes to occur, it would seem that several volcanoes located above the ice and containing rich halogen gases
04:19must become active in a fairly short period of time and remain powerful for tens or even hundreds of years.
04:25Antarctica contains about 80% of all the fresh water in the world.
04:29And if all this ice melted, the global sea level would increase by nearly 60 meters.
04:34And we would just have to look for a new planet to live on.
04:38But this scenario is unlikely.
04:40It is more likely that underwater eruptions will lubricate the ice floes and send masses of water into the ocean.
04:47But this would not be the end of the world.
04:50An extremely powerful and furious supervolcano could reach it, and this has already happened in the past.
04:56More than 200 million years ago, the world underwent a major transformation,
05:01with not one or two, but four massive volcanic eruptions.
05:05The central atlantic magmatic province erupted continuously for 600,000 years.
05:10It was at Wrangelia, a large mass of land and once a supermassive volcano,
05:14spreading over what is now the territory of British Columbia and Alaska.
05:19But it was neither lava nor volcanic ash that devastated the environment.
05:23The eruption exploded the carbon levels.
05:26The planet has never been the same after that.
05:29This volcanic activity would have allowed dinosaurs to become the giants we discovered in Jurassic Park.
05:35It would have triggered a rainy season of 2 million years, and made the planet warm and humid.
05:40Dinosaurs loved it.
05:42Researchers have dug deep into the sedimentary layers, under an old lake in Asia, to discover its secrets.
05:48They found traces of volcanic ash and mercury, signs of these eruptions.
05:54They have also been able to confirm the great increases in carbon dioxide levels.
06:00This would have made the atmosphere torrid, and the rain began to fall abundantly.
06:06The bad news is that another eruption like this could occur.
06:11The supervolcano located under Yellowstone National Park has been sleeping for nearly 70,000 years.
06:16But if it woke up, it would be much more catastrophic than the eruption of Mount St. Helens in 1980.
06:22It is considered the most disastrous volcanic eruption in the history of the United States.
06:27It occurred after two months of earthquake and magma injection, which weakened and destroyed the entire northern face of the mountain.
06:34The eruptive column rose to more than 24,000 meters in the atmosphere,
06:38and spread ashes over 11 American states and several Canadian provinces.
06:43And the last Yellowstone eruption was 1,000 times larger than this one.
06:48Yellowstone soil lies on a hot spot, composed of molten and semi-molten rock.
06:53This magma flows below the park, about 8 km deep, and inflates the soil like a balloon.
07:00But when the magma cools, the soil returns to its usual state.
07:05Volcanologists have been monitoring this activity for a century.
07:09They noticed that the soil had risen by about 25 cm about twenty years ago.
07:14But since 2010, it has been going down.
07:17Experts say that we do not have to fear major eruptions in the near future.
07:22The end of the world is therefore not for tomorrow.
07:24But a certain underground activity is currently attracting the attention of scientists.
07:29As humans were not witnesses to everything that could have happened to Yellowstone,
07:33it is rather difficult to say with certainty what is lurking below.
07:37Yellowstone has undergone several major eruptions over the last few million years.
07:42They occurred with great regularity, with intervals of 6 to 800,000 years.
07:48The last major eruption took place about 640,000 years ago,
07:52and it truly remodeled the entire landscape,
07:55dispersing ashes and debris all the way to Louisiana.
07:59It is still possible to see the consequences in Yellowstone caldera.
08:03Experts say that a massive eruption like this one is an unlikely scenario.
08:08It is more likely that we are witnessing steam and hot water eruptions,
08:13or, at worst, lava flows.
08:16But when and with what force this will occur remains a mystery to scientists.