00:00Tick-tock. No, not the app. A clock. You see, scientists already know the exact doomsday date.
00:07Tick-tock. The countdown has started. We only have 250. No, not years. Millions of years left
00:15on this beautiful planet we call Earth. Well, let me apologize first. I might have scared you
00:20with all these end-of-the-world things. You and I certainly won't live to witness it,
00:25but we already know when it will all go downhill and, most importantly, why.
00:30This 250 million years deadline is not precise. If we change our ways, humans can stick around for
00:37more or less, depending on what way we choose. Researchers ran some computer simulations
00:43and found that Earth might be left without any mammals if temperatures kept climbing to between
00:49104 and 158 degrees Fahrenheit. What's the culprit? Well, it's mainly our love for fossil fuels and the
00:57greenhouse gases we keep pumping into the atmosphere. It's easy to think that mass extinctions are a
01:03thing of the past, especially since the last big one wiped out dinosaurs 66 million years ago. But
01:09surprise! We're actually overdue for another one, and this time, it's all on us.
01:15Throughout Earth's history, there have been 5 mass extinctions, and it's been 66 million years since
01:21the last one. But this upcoming one is special. It's totally human-made. As Earth's tectonic plates
01:28shift over millions of years, they eventually come together to form supercontinents. This could lead
01:33to some pretty serious natural disasters, and, well, it might as well mean the end. Having one continent
01:40instead of seven is already pretty extreme, as it will totally make us rethink the way we live.
01:46Scientists said that a new supercontinent would create a trio of problems — the continentality
01:52effect. No, I didn't make that word up. A hotter sun and rising CO2 levels, resulting in a superhot planet.
02:00This would lead to tough living conditions for mammals with limited food and water. If temperatures hit
02:06104 to 122 degrees Fahrenheit — and maybe even more extreme fluctuations — humans and lots of other
02:13species would struggle to cope, since we can't shed heat effectively through sweating.
02:18Some experts believe the future looks pretty grim. CO2 levels could end up being double what they are
02:24now, and the sun's radiation could increase by about 2.5%. With the supercontinent likely to be in
02:31hot, humid tropics, much of the planet could be facing extreme heat. Finally, in about 250 million
02:38years, Earth is expected to morph into a doughnut shape with a big inland sea in the middle, leaving
02:44the Pacific Ocean to cover most of the surface. Honestly, no matter how well scientists crunch the
02:50numbers, they can't see the future — especially when it's this far out. But hey, those who ignore history
02:56are doomed to repeat it. So let's jump into the history of the five massive extinctions that have
03:02already happened. The late Ordovician mass extinction hit around 445 million years ago and was a huge deal
03:10for ocean life, wiping out up to 60% of marine species, including 85% of all marine creatures. Unlike
03:18other extinctions, it really didn't change ecosystems much. It had two main phases. First, the climate cool
03:25due to glaciation, causing sea levels to drop, and many marine animals to lose their homes,
03:31leading to new cold-water ecosystems. Then, when the ice melted, warming returned,
03:36but oxygen levels plummeted, creating toxic ocean spots. I know, it all sounds horrible,
03:43but let's see the results. The planet is still habitable, marine life is booming, and, by the way,
03:49there are even species — some hard-bodied arthropods like horseshoe crabs — that are still around.
03:55So, from our perspective, it feels like it wasn't a disaster so much as a step for further
04:00development of our planet. Bye, let's not make premature conclusions and take a look at the next
04:07mass extinction. The late Devonian extinction was a big deal in Earth's history, happening about 272
04:14million years ago. The main event during this time was called the Kelwasser event, which wiped out about
04:2019% of all family groups and half of all types of living things in the oceans. Another extinction,
04:27the Hangenberg event, occurred around 359 million years ago and marked the end of the Devonian period.
04:34This extinction wasn't just one event, but might have happened over a long time,
04:38possibly from 500,000 to 25 million years. Some scientists think that there were as many as seven
04:46separate extinction events during this period. By the late Devonian, plants and insects were
04:51starting to thrive on land, and oceans were filled with huge coral reefs. The continents were also
04:57moving together to form what we know as Pangea. Most of the creatures that disappeared were in the
05:03oceans, like brachiopods and trilobites, especially the ones that built reefs.
05:08The reasons for this extinction are still a mystery. Some ideas include changes in sea levels, lack of
05:14oxygen in the ocean, global cooling, or even volcanic activity. There's also a theory that a comet hit
05:21Earth. Interestingly, it seems that the loss of diversity came more from fewer new species forming
05:28rather than a spike of species dying out. During this extinction, oceans became low in oxygen,
05:35which helped preserve some organic material. This, along with the porous rocks from that time,
05:40made Devonian rocks a valuable source of oil, especially in places like Canada and the US,
05:46way before they became Canada and the US. So far, these terrible mass extinction events
05:53don't sound that bad. About 250 million years ago, there was a huge event called the Permian-Triassic
06:00Extinction, often called the Great Dying. It was probably the worst extinction event ever on Earth.
06:07During this time, a whopping 59% of all biological families and 83% of different kinds of living
06:14things disappeared. This included 81% of marine life and 70% of land animals. Even insects were hit hard.
06:24Scientists believe the main cause of this mass extinction was massive volcanic eruptions in what
06:29we now call the Siberian Traps. These eruptions released a ton of gases, like sulfur dioxide and
06:36carbon dioxide, which messed up the oceans and made it hard for many creatures to survive.
06:41The atmosphere's carbon dioxide levels skyrocketed, from about 400 parts per million to 2500 parts per
06:48million. Other possible reasons for this extinction include burning oil and coal during these eruptions,
06:56intense weather patterns like El Niño, and even a possible asteroid strike. All of these factors
07:02combine, creating a really tough environment for life on Earth at that time. Okay, this one seems
07:08serious. Let's proceed though, shall we? The Triassic-Jurassic extinction event, happening around 200
07:16million years ago, was a major wipeout of many species, both on land and in the ocean.
07:21In the oceans, between 23 to 34% of marine life vanished. On land, most reptiles, except for
07:29crocodiles, dinosaurs, and pterosaurs, those flying reptiles, went extinct. Some of the reptiles that
07:36went extinct were once very common. Luckily, plants, early mammals, and the groups that survived,
07:42like dinosaurs and pterosaurs, thrived and became the main animals for the next 135 million years.
07:49Scientists think this extinction might have been caused by huge volcanic eruptions,
07:54which released lots of carbon dioxide into the air. This led to global warming and made the oceans more
08:00acidic.
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08:30and you'll observe that.
