Prática de Shadowing: What Would Happen If an Asteroid Hit the Ocean? - Aprenda a falar inglês com vídeo
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70 % of this planet is water, which means that if something falls out of the sky and hits us,
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the odds are overwhelmingly that it lands in the ocean rather than on land.
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Most people find that reassuring.
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The ocean feels like a cushion.
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It is deep, it is empty, and there are no cities out there to destroy.
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If a mountain of rock is going to fall on the earth,
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surely the middle of the Pacific is the best possible place for it to land.
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That instinct is completely understandable, and it is wrong in a way that took scientists a surprisingly long time to work out.
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Because water does not absorb an impact like that.
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Water does something far worse.
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It takes the energy, holds onto it and then carries it thousands of kilometers to a coastline where people actually live.
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And that is only the first of the three separate disasters an ocean impact sets in motion.
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And it is not the one that kills the most people.
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By the end of this you will understand why the ocean is not a cushion at all.
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It is a delivery system.
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Before we drop anything, we have to be honest about scale.
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Because asteroid hits the ocean covers an enormous range of outcomes, from nothing at all to the end of civilization.
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Small objects hit our atmosphere constantly.
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Every single day, tons of material from space runs into the Earth, and almost all of it burns up long before it reaches the surface.
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Those are the shooting stars you see on a clear night, and they pose no threat to anyone.
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Push the scale up to a few meters across, and you get the events that occasionally make the news.
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An object explodes in the upper atmosphere, produces a spectacular fireball, rattles some windows,
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and scatters fragments across a landscape.
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Anything landing in the ocean at that size vanishes without a single person noticing.
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The situation changes at somewhere in the region of a hundred meters.
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An object that size carries enough energy to survive the atmosphere and deliver a serious impact.
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And if it lands in water, it starts generating waves that matter.
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At around a kilometer, you are looking at a genuine global threat, regardless of where it hits.
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And at 10 to 15 kilometers, which is roughly the size of the object that ended the dinosaurs, the location almost stops mattering.
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That is not a regional disaster, that is a planetary reset.
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For most of this video, we are going to focus on the range that is actually most likely to happen in a human lifetime,
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which is the few hundred meter object, because that is where the odds and the consequences intersect most uncomfortably.
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But we will come back to the big one, because the day the dinosaurs died was an ocean impact,
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and what happened next is genuinely difficult to imagine.
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Picture a rocky object 300 meters across on a collision course with the middle of an ocean.
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It is traveling somewhere in the region of 20 kilometers per second.
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The first thing to understand is that at that speed our atmosphere barely exists.
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A hundred kilometers of air, the thing that protects every living creature on this planet, is crossed in a handful of seconds.
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The object compresses the air in front of it so violently that the air itself glows white -hot,
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and anyone within sight of the sky sees a light brighter than the sun tearing across it.
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Then it reaches the water and here is where our intuition fails us completely.
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When you imagine something falling into the sea, you probably picture a splash.
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Something enters, water parts, water closes over it, ripples spread out.
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That image is based on a lifetime of watching objects drop into water at ordinary speeds.
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At 20 km per second, water does not behave like a liquid at all.
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It does not have time to flow out of the way.
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On the time scale of the impact,
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seawater behaves more like a solid and the collision is closer to rock striking rock than to a stone hitting a pond.
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The object does not sink.
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It is.. destroyed.
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It is annihilated on contact, converting an enormous quantity of kinetic energy into heat and pressure in an instant,
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and in the process it vaporizes a colossal volume of seawater around it.
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What opens up in the ocean at that moment is not a splash.
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It is a crater in the water itself, A transient cavity that can be several kilometers across and,
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in deeper water, may reach all the way to the sea floor.
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For a brief moment, there is a hole in the ocean with steam -filled walls, and you could look down through it and see the seabed.
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The ocean, of course, does not tolerate that for long.
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The cavity begins collapsing almost immediately, and this is the moment that creates the disaster.
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Billions of tons of seawater rush inward from every direction to fill the hole.
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And all of that water arrives at the center at the same time, with nowhere left to go but up.
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It rebounds, forming an enormous column of water that rises high into the atmosphere before falling back and collapsing again.
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near the impact point we are potentially talking about waves hundreds of meters high
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now this is the point where most explanations of ocean impacts go badly wrong
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and I want to correct it carefully because the correction is actually more interesting than the myth
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The common claim is that an ocean impact produces a wall of water hundreds of meters tall
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that sweeps across the entire ocean and washes over continents.
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That version is not what the physics predicts, and it is worth understanding exactly why.
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Impact waves and earthquake tsunamis are not the same animal.
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An earthquake tsunami is generated when a long section of the seafloor, sometimes hundreds of kilometers of it, shifts vertically all at once.
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That displaces an enormous volume of water along a very long front, and it produces a wave with a very long wavelength.
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Long wavelength waves are extraordinarily efficient at crossing oceans, losing very little energy on the way,
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which is why a quake off one coast can devastate a shoreline on the far side of the world many hours later.
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An impact wave is generated by a single point and the waves it produces have much shorter wavelengths.
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Short wavelength waves lose energy far more rapidly as they spread.
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The wavefront expands outward as a growing circle and the same energy is distributed across an ever larger circumference,
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so the height falls off quickly with distance.
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So the honest picture is this.
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Close to the impact, the waves are apocalyptic and nothing survives.
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At intermediate distances, they are still catastrophic, and by the time they reach a distant continent, they may be far smaller than the myth suggests,
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though still large enough to be a serious coastal disaster.
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That sounds like good news, and up to a point it is, but there is a detail hiding in that reassurance that turns it around completely,
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and it has to do with where we choose to live.
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Here is the uncomfortable arithmetic.
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Something in the region of 40 % of humanity lives within 100 kilometers of a coast.
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The great cities of the world are overwhelmingly coastal because for the whole of human history,
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access to the sea has meant access to trade, food and travel.
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We built our civilization at the water's edge on purpose.
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That means the specific weakness of an ocean impact, its ability to convert energy into moving water,
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is aimed directly at where we keep almost half our population and a large fraction of our infrastructure.
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And there is a second problem that makes the wave heights out in the open ocean misleading.
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When a wave moves into shallow water near a coastline, it slows down and the energy it carries has to go somewhere.
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It goes upward.
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The wave grows dramatically as it approaches the shore, a process called shoaling.
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A wave that seems modest in deep water can become something entirely different when it arrives at a continental shelf.
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Local geography then makes it worse or better in ways that are extremely difficult to predict.
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A wave funneled into a narrowing bay is amplified.
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A wave arriving at a gently sloping shelf pushes much further inland.
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A map meeting a steep coastline may reflect and dissipate.
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So the real answer to how bad an ocean impact would be depends enormously on where in the ocean it lands,
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which coastlines face it, and the shape of the seabed leading up to them.
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An impact in the middle of the South Pacific and an impact in the North Atlantic are entirely different events for humanity.
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And all of that is still only the first of the three disasters.
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Because there is something else coming out of that impact site, and unlike the waves, it does not weaken with distance.
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Remember what happened in the first second.
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A colossal volume of seawater was vaporized instantly.
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That water does not disappear.
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It is thrown into the atmosphere as steam, along with pulverized rock and dust, and, if the impact reaches the sea floor,
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material excavated from the crust itself.
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An ocean impact injects an enormous quantity of water vapor into the upper atmosphere.
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Water vapor is a greenhouse gas.
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Large quantities of it high in the atmosphere can affect the planet's energy balance, and researchers studying ocean impacts have pointed out
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that this is a genuinely distinctive feature of a water strike compared to a land strike.
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There is also the question of what such an injection does to the ozone layer, which shields the surface from ultraviolet radiation.
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So you get competing effects, and the net outcome depends on the size of the impact and the specific conditions.
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The exact magnitude of all this is an area of active research rather than settled fact, And the honest position is
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that the climate consequences of a mid -sized ocean impact are less well understood than the wave effects.
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But the principle is clear.
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An ocean impact is not just a wave -making machine.
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It is also an atmospheric event, and the atmosphere does not stop at any coastline.
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And then there is the third disaster,
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which is the one that would probably kill the most people and it involves no water and no dust at all.
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Imagine the wave has come and gone.
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Imagine it struck a stretch of coastline somewhere in the world, destroying ports, cities, refineries, airports and rail links.
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Now think about what a modern civilization actually is.
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It is a network.
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Food is grown in one place and eaten thousands of kilometers away.
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Medicines are manufactured in a handful of facilities and distributed globally.
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Fuel moves by sea.
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Electronics move by sea.
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A staggering share of everything you own passed through a port at some point.
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And those ports are precisely what a tsunami destroys most efficiently.
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Modern supply chains are also optimized for efficiency rather than resilience.
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Most of what you buy is not sitting in a warehouse waiting for you.
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It is scheduled to arrive shortly before it is needed, because storage costs money.
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That system is extraordinarily efficient and extraordinarily fragile.
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Take out a cluster of major ports on one side of an ocean
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and the effects propagate through that network in ways
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that reach people who never saw the wave and live nowhere near the sea.
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Shortages appear in places that were physically untouched.
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Prices spike.
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Manufacturing stalls because a single component is no longer available.
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We have watched smaller versions of this happen in living memory,
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when a single blocked shipping route or one disrupted factory sent measurable ripples through the global economy for months.
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So the death toll from an ocean impact is not really a question about the height of a wave.
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It is a question about how well a globally interconnected civilization handles losing a section of its coastline.
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And the honest answer is that we do not know, because we have never tested it.
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Now, let us go back to the one that we know actually happened.
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66 million years ago, an object somewhere in the range of 10 to 15 km
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across across struck the earth near what is now the Yucatan Peninsula.
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That was an ocean impact.
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It landed in a shallow sea.
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At that scale, everything I have described stops being a regional disaster and becomes something else entirely.
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The waves generated were beyond anything in human experience,
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and evidence of enormous disturbance in the sediments around the Gulf region records their passage.
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But the waves were not what ended the dinosaurs, and this is the detail that matters most for understanding impact risk.
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The rock at that particular site was rich in sulfur -bearing minerals, and the impact vaporized it and threw it into the atmosphere,
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where it formed a haze that reflected sunlight away from the surface.
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Combined with soot from global wildfires and enormous quantities of dust, the result was a collapse in the sunlight reaching the ground.
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When sunlight fails, photosynthesis fails.
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And when photosynthesis fails, every food chain on the planet that depends on it comes apart from the bottom up.
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Around three -quarters of species on Earth died and every dinosaur larger than a house cat disappeared.
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So the lesson from the only large ocean impact in the record is a strange one.
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The water was not the main weapon, the atmosphere was.
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And that is worth holding on to because it means that when we assess the risk from a future impact,
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the question of what the object hits and what that material does
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when it is thrown into the sky may matter more than whether it lands on land or at sea.
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Here is the genuinely hopeful part, and it is not a small one.
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We are, as far as we know, the first species in the history of this planet with the ability to see one of these coming
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and do something about it.
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There are ongoing
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The following survey programs mapping near -earth objects and the large ones, the civilization -ending kilometer -plus objects,
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are the easiest to find because they are the brightest.
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A substantial proportion of that population has been catalogued
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and none of the known ones are on a collision course in the foreseeable future.
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Objects in the 100 to 300 meter range are much harder to spot, far more numerous and entirely capable of destroying a coastline.
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Those are the ones that could genuinely surprise us.
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That is not a complete planetary defense system, but it is a proof of concept,
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and it moves the whole problem out of the category of things we simply endure.
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The catch is time.
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Deflection works by making a very small change to an object's path a very long way in advance
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so that the tiny nudge compounds into a large miss by the time it reaches us.
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That requires years of warning, which requires finding the object first,
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which brings the entire subject back to something unglamorous.
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The single most valuable thing we can do about asteroid impacts is not build weapons.
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It is look.
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So what would happen if an asteroid hit the ocean.
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For a small object, nothing at all, and nobody would ever know.
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For something a few hundred meters across, a regional catastrophe aimed squarely at the coastlines where we have concentrated our cities,
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our ports, and nearly half of our species,
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followed by an economic disruption that would reach far inland to people who never saw a drop of the water.
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If you enjoyed this, subscribe, because we are only getting started.
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And tell us in the comments whether you think we would actually be ready.
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Watch next as we reconstruct the day the dinosaurs died, hour by hour.
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Vocabulário e dicas de fala para esta lição
Esta aula de conversação usa o vídeo “What Would Happen If an Asteroid Hit the Ocean?”. As palavras que mais se repetem: impact, ocean, wave, object, atmosphere. Este vídeo tem 193 frases e 2662 palavras para praticar shadowing. A fala dura 19:59. O falante mantém um ritmo estável de cerca de 133 palavras por minuto, confortável para o shadowing. Apenas 79% das palavras estão entre as 3.000 mais comuns do inglês, por isso o vocabulário é exigente.
Vocabulário principal deste vídeo
15 palavras do vídeo que vale a pena aprender, com pronúncia e significado:
| Palavra | Pronúncia | Significado |
|---|---|---|
| atmosphere substantivo | /ˈætməsˌfɪɹ/ | atmosfera |
| coastline substantivo | linha costeira | |
| disaster substantivo | /dɪˈzɑːs.təː/ | desastre |
| enormous adjetivo | /ɪˈnɔː.məs/ | enorme, gigante |
| meter substantivo | /ˈmitəɹ/ | contador |
| civilization substantivo | /ˌsɪv.ɪ.laɪˈzeɪ.ʃən/ | civilização |
| arrive verbo | /əˈɹaɪv/ | chegar |
| generate verbo | /ˈd͡ʒɛn.ə.ɹeɪt/ | gerar |
| quantity substantivo | /ˈkwɑn(t)ɪti/ | quantidade |
| dinosaur substantivo | /ˈdaɪnəsoɹ/ | dinossauro |
| dust substantivo | /dʌst/ | pó, poeira |
| collapse verbo | /kəˈlæps/ | desabar, ruir |
| collision substantivo | /kəˈlɪʒn̩/ | colisão |
| sunlight substantivo | /ˈsʌnˌlaɪt/ | luz do sol |
| asteroid substantivo | /ˈæst(ə)ɹɔɪd/ | asteroide, planetoide |
Phrasal verbs que você vai ouvir
| Palavra | Pronúncia | Significado |
|---|---|---|
| fall off verbo | cair | |
| point out verbo | apontar | |
| slow down verbo | desacelerar | |
| spread out verbo | espalhar-se | |
| take out verbo | tirar, remover | |
| work out verbo | /ˌwɝk ˈaʊt/ | calcular |
Gramática neste vídeo
As estruturas que o falante mais usa, com as palavras exatas do vídeo:
| Estrutura | No vídeo |
|---|---|
| Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz | is crossed · is based · is annihilated |
| Present perfect have/has + particípio passado — uma ação passada que ainda importa agora | has meant · have pointed · has come |
| Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa | water, which means · kilometers, which is · people who never |
Pronúncia para ficar de olho
- Os sons de “th”: earthquake /ˈɝθkweɪk/, myth /mɪθ/, wavelength /ˈweɪvˌlɛŋ(k)θ/, photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/
- Os sons de “sh” e “zh”: civilization /ˌsɪv.ɪ.laɪˈzeɪ.ʃən/, collision /kəˈlɪʒn̩/, efficient /ɪˈfɪʃənt/, shallow /ˈʃæloʊ/, shelf /ʃɛlf/
- Palavras longas — acerte a sílaba tônica: civilization /ˌsɪv.ɪ.laɪˈzeɪ.ʃən/, genuinely /ˈd͡ʒɛn.ju.ɪn.li/, humanity /hjuˈmænɪti/, planetary /ˈplænɪˌtɛəri/, overwhelmingly /ˌəʊ.vəˈwɛl.mɪŋ.lɪ/
Sons difíceis para falantes de português:
- Consoante final — sem acrescentar um “i” depois: generate /ˈd͡ʒɛn.ə.ɹeɪt/, dust /dʌst/, sunlight /ˈsʌnˌlaɪt/, asteroid /ˈæst(ə)ɹɔɪd/, efficient /ɪˈfɪʃənt/
- /l/ final — a língua toca o céu da boca, não vira “u”: coastal /ˈkoʊstəl/, handful /ˈhæn(d)fʊl/, rail /ɹeɪ(ə)l/, settle /ˈsɛtəl/, principle /ˈpɹɪn.sɪ.pəl/
- /h/ — um sopro suave, diferente do “r”: nowhere /ˈnoʊ.(h)wɛɹ/, humanity /hjuˈmænɪti/, handful /ˈhæn(d)fʊl/, warehouse /ˈwɛə(ɹ)haʊs/, behave /bɪˈheɪv/
Como praticar com este vídeo
- Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
- Faça shadowing frase por frase na velocidade normal, repetindo cada uma até o seu ritmo ficar igual ao do falante.
- Grave a sua voz e compare com o original, prestando atenção a palavras como atmosphere, coastline, disaster.
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.