What's happening to Earth's core? - Shannon Odell

382,091 views ・ 2023-07-13

TED-Ed


Please double-click on the English subtitles below to play the video.

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A hydrogen atom travels high within the outermost layer
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of the Earth’s atmosphere.
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This particular atom first entered the exosphere millions of years ago,
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and during its tenure on Earth,
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it’s spent time in the waves of the Atlantic Ocean,
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the ground soil of the Amazon,
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and even the steam rising off a boiling pot of spaghetti.
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But today, traveling 30 times faster than the speed of sound,
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it overcomes the Earth’s gravitational pull and escapes,
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joining the roughly 90 tons of material that leak out of our atmosphere each day.
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This daily whale-sized atmospheric loss is just one example
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of how the Earth is leaking.
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Atoms, energy, and molecules seep from one layer of the planet to another.
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And for Earth, whose stability is necessary to sustain life,
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these leaks can seem troubling.
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To better understand the extent of the planet’s imperfect plumbing,
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and when it becomes a problem,
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let’s visit two more leakage sites.
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Our second spot takes us to the Earth’s surface,
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to a field in Central Appalachia.
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Below, a 1,500 meter deep shaft connects an oil reservoir
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with the Earth’s surface.
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The oil supply here is dried up, leaving the site neglected and abandoned.
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But this underground reservoir also houses the potent greenhouse gas methane,
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which continues to travel up the shaft and escape through cracks and loose pipes.
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This leaky well joins the more than 3 million abandoned wells
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scattered throughout the US,
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that collectively emit, by lower estimates,
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280,000 metric tons of methane each year.
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Our final leakage point takes us deep within the innermost boundary
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of the Earth, the core.
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Heat, originating from the formation of our solar system,
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drives the rotation of liquid metal around the solid inner core.
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The motion, in turn, creates the planet’s magnetic field,
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a barrier that protects it from cosmic radiation and solar wind.
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But the core isn't perfectly insulated, so heat constantly leaks,
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escaping to the surrounding mantle
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and driving plate tectonics and magmatic activity.
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As a result, the core’s outer molten metal is slowly solidifying.
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Once fully cooled, the magnetic field will disappear,
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leaving us exposed to the Sun’s harshest rays.
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The Earth clearly has some cracks and bleeds.
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Should we be worried?
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Thankfully, the immediate risks of our hydrogen leak are low.
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At its current rate, it would take over 150 billion years
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to lose all our hydrogen to space.
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The same goes for our core leak.
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Scientists estimate the core won't completely cool
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for another 700 million to several billion years.
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Methane emissions, however,
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have the power to alter our Earth's climate within the next decade.
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The gas’s unique structure efficiently absorbs energy radiating off the Earth,
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trapping it in the atmosphere as heat.
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This gives methane incredible warming potential,
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86 times that of carbon dioxide.
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The impact of methane escaping from abandoned wells in the US
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is comparable to burning 10 billion pounds of coal each year.
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As abandoned wells in most of the world’s top oil producers
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have yet to be extensively counted or surveyed,
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the global emissions of all abandoned wells is likely much, much higher.
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And they join the estimated 570 million tons of methane
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emitted by other anthropological and natural sources each year.
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Beyond their climate impact,
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these unsealed wells can leach methane and other toxic gases
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into nearby groundwater,
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contaminating drinking water and impacting local ecosystems.
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Luckily, non-producing oil wells can be plugged by pumping cement
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into their depths.
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While many state and federal governments require oil and gas companies
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to plug defunct wells,
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plugging comes at a high expense,
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so companies have historically dodged policies.
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For decades, these leaky, low-producing, and economically non-viable wells
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were sold off and abandoned.
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It's clear that oil and gas companies won't fix this problem on their own.
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It'll take concerted governmental efforts,
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such as placing high fees on methane emission
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and coordinated oversight on plugging,
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to make sure companies are held accountable.
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But the problem starts before these wells are abandoned.
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Within the US, active oil and gas production
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emits massive amounts of methane,
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about 28 times that of abandoned wells.
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The best way to eliminate this leak is to stop drilling oil and gas wells
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in the first place.
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