تدريب Shadowing: The First Mass Extinction as Explained by Lindsay Nikole - تعلم التحدث بالإنجليزية عبر الفيديو
جارٍ إنشاء الدرس...
1
Extinction is a fact of life on Earth.
2
Our planet is always changing, and not every species can handle the changes.
3
So it's pretty normal for a handful of species to go extinct every year.
4
But sometimes, huge changes cause lots of extinction, and tons of species disappear in a relatively short time all over the world.
5
A mess.
6
Extinction.
7
These events are terrifying and fascinating.
8
By studying mass extinctions, we learn how our world got the way it is now, and where it's headed.
9
Right now, rates of extinction are so high that we might be on the verge of a modern mass extinction.
10
Experts predict that if this trend continues, we could lose up to 50% of all species on Earth by 2050.
11
So, for this video series, I'm partnering with Colossal, the de-extinction company, working to prevent the next mass extinction.
12
Throughout Earth's history, there have been five famous mass extinction events, the Big Five.
13
In each one, more than 70% of life on Earth died out.
14
In this series, we're going to explore the causes and effects of each of them, one by one, to lay out what we know about mass extinctions of the past so we can prevent another one.
15
First up is the oldest of the big five, the Ordovician mass extinction.
16
The Ordovician period was from 485 to 444 million years ago.
17
During this time, the Earth was like an alien world.
18
There were no familiar shapes among the continents or oceans.
19
Most of the land masses were in the southern hemisphere, like the supercontinent Gondwana.
20
The world was very warm and had very high sea levels, which created lots of warm, shallow ocean habitats.
21
Those warm oceans are where we find Ordovician life, like Eurypterid sea scorpions crawling along the ocean floor.
22
Some of them got to almost six feet long.
23
Squid-like cephalopods with massive shells drifted through the water.
24
The biggest ones, like Endoceros, were almost 20 feet long.
25
I like those cones a lot.
26
There were ancient corals, sea lilies, sponges, lamp shells, et cetera.
27
This was also the time of the trilobites.
28
Big ones, small ones, smikey, smikey, spiky and smooth, crawling and swimming and burrowing all over the ocean.
29
There were also fish, too.
30
They were strange, jawless species, including eel-like conodonts, and also ones like Sacobambaspis, a tiny jawless fish that had armored plates on their heads.
31
Almost all life at this time lived in the water.
32
The land was almost completely barren, except for some of the earliest land plants that were just starting to creep up.
33
Fossil spores provide evidence that simple non-vascular plants, similar to like mosses and liverworts, forming green carpets over the rocks, very mid-century.
34
At the end of the Ordovician, in the last two million years or so of the period, this alien world was rocked by a global mass extinction.
35
In the fossil record, we see about 85% of species disappear.
36
Trilobites, corals, fishes.
37
Every group experienced major loss.
38
This is the first time that animal life on Earth experienced a global collapse of this scale.
39
That mean Noah.
40
But a mass extinction doesn't happen for no reason.
41
Rocks and fossils from the late Ordovician contained clues to the cause of this catastrophe.
42
Specifically, changes in the chemical makeup of certain minerals reflect a massive climate fluctuation.
43
First, the Earth got slapped with a global cooling, and then slapped with a global warming.
44
A one-two punch of destruction.
45
It starts with an event called the Hernantian Glaciation, the Ordovician Ice Age.
46
Scientists have identified geologic evidence of ice sheets at the South Pole, kind of like the ice that covers Antarctica today.
47
Also, a drop in sea level of about 300 feet, while that water was frozen into ice.
48
Global temperatures dropped at least 5 degrees Celsius, disrupting the formation of certain minerals and leaving telltale evidence in rocks and fossils.
49
All of this was bad for sea life.
50
Colder temperatures were a big problem for any species that got very cozy in those warm waters.
51
And also, as sea levels fell, the water drained away from coastlines and shallow seas.
52
So, their habitats were done-zo anyway.
53
Changes to sea level and water temperature also disrupt ocean chemistry and circulation, which can mess with animal migrations, reproduction, even down to the basic finding food and breathing properly.
54
But an ice age doesn't happen for no reason either.
55
The cause of the cooling was a change in the atmosphere.
56
Minerals from the late Ordovician period show a change in their carbon composition, the kind of change that happens when atmosphere is running low on carbon dioxide.
57
Carbon dioxide is a greenhouse gas, which means it traps heat in the atmosphere.
58
Less CO2 in the air means less trapped heat, means cooler global climate.
59
Exactly why CO2 levels plummeted in the late Ordovician is hard to say for sure, but there are two prime suspects that were suspiciously active at this time in Earth's history.
60
Volcanoes and plants.
61
Volcanoes are where baby rocks come from as lava cools, it forms new solid rock.
62
And if that rock is exposed to the air, it can experience chemical weathering, which is a process that pulls CO2 out of the atmosphere.
63
Lava rocks from the late Ordovician provide evidence that volcanoes were erupting at that time, producing lots of new rocks that were weathering away.
64
But you know what else draws CO2 out of the air?
65
Yeah, plants.
66
Like I said before, land plants were just getting started in the Ordovician, just like we breathe in oxygen to fuel our bodies, plants breathing carbon dioxide to power their photosynthesis.
67
As plants became more common on land, they pulled more and more carbon dioxide from the atmosphere.
68
Land plants also churn up the ground, pulling up mineral nutrients that end up getting washed into the oceans.
69
Similar nutrients can also be released from volcanic eruptions and from weathering rocks.
70
As those nutrients concentrate in shallow waters, they can become fuel for massive blooms of algae, cyanobacteria, which also suck up carbon dioxide.
71
So some combination of land plants, volcanoes, and algal blooms was pulling lots of carbon out of the Ordovician atmosphere.
72
And once the cooling trend got started, it snowballed.
73
As water freezes into ice, sea levels drop, which exposes more land to weathering, which draws down more CO2, which means more cooling.
74
And on, and on, and on.
75
Ice is also very reflective, so sunlight bounces off of it, taking some heat with it.
76
In the late Ordovician, the giant continent Gondwana sat right over the South Pole, so there was lots of room for massive ice sheets.
77
As the ice sheets grew, they reflected more and more heat, and the air got colder and on and on and on.
78
Freezing water also acts as a trap for carbon dioxide.
79
Rain pulls carbon dioxide down with it.
80
When the water freezes the CO2 gets stuck in the ice.
81
This is called a positive feedback loop, a series of events that reinforce themselves.
82
But if you were to ask the Ordovician species they'd say it was very negative for them.
83
Some species were pretty quick to adapt to the changing climate.
84
Certainly the Ordovician fossil sites are full of cold adapted species that establish new ecosystems in these cooler conditions.
85
But then the second slap.
86
Right before the end of the Ordovician the Ice Age All those trends we see in the rocks and fossils become reversed, reflecting new trends of rising temperatures,
87
rising sea levels, and rising carbon dioxide in the atmosphere.
88
Ocean habitats got messed up again.
89
Those cold-adapted ecosystems that had literally just settled were destroyed by warming temperatures.
90
And once again, there were global changes to ocean chemistry and circulation, as well as the shape of shallow ocean habitats.
91
Rising temperatures and CO2 in the ocean can also lead to ocean acidification a change in seawater chemistry
92
that dissolves the shells and skeletons of species like corals and plankton, which form the foundation of ocean ecosystems.
93
The rock record of the latest Ordovician also contains deposits of black shale, a type of rock that forms from sediment deposited in oxygen-poor water.
94
Ocean circulation is responsible for carrying oxygen from the atmosphere down to deeper waters.
95
When that circulation changes, certain waters can become deprived of oxygen.
96
Also, when those massive blooms of algae die, they decompose, which is a chemical process that sucks up oxygen from the water.
97
So, between changing circulation patterns and lots of decomposing microbes, oxygen levels were dropping all over the ocean, suffocating marine life and leaving behind those black shales.
98
And just like ice ages don't start for no reason, they also don't end for no reason.
99
In this case, the reason is most likely those volcanoes.
100
I said before that volcanoes can lead to cooling, which is true, especially on short time scales, but volcanic gases also contain lots of carbon dioxide.
101
So when When volcanic eruptions continue for a long time, they release tons of CO2 into the atmosphere.
102
Then we get those runaway processes again, in reverse.
103
More CO2 traps more heat, so the climate gets warmer.
104
Warmer temperatures melt more ice, which reflects less heat, releases trapped carbon dioxide, leading to more warming.
105
Melting ice also floods the seas, raising sea levels, flooding exposed to land, protecting the rocks from weathering, so less CO2 is being pulled out of the air, and so on, and so on, and so on.
106
And before you know it, the ice age is over.
107
The world is warm again, and ecosystems are in shams.
108
By the time it's all done, about 443 million years ago, most of that alien ordovician biodiversity is gone.
109
About 85% of species became extinct.
110
Some of the hardest hit groups were temperature-sensitive species like corals, sponges, and plankton.
111
And so many other species rely on these animals for food and shelter that with them gone, entire ecosystems collapsed.
112
Some groups eventually recover pretty well.
113
Sea lilies and fish go on to become highly diverse and successful again.
114
Other groups never regain their former glory.
115
Trilobites got hit pretty hard, and they're never again as widespread or varied as they were in the Ordovician.
116
And some groups vanished completely, like those giant Endoceracephalopods.
117
And in case you're wondering, land plants were fine.
118
They were pretty much barely affected.
119
They're probably responsible for this whole fiasco, but it's everyone else that suffered for it, as that's just the way it works.
120
But life on Earth goes on.
121
After the Ordovician comes the Silurian Period.
122
Recovery starts off slow, but gradually, plants and animals develop all new ecosystems throughout the seas, and eventually on land too.
123
And soon the world is once again home to an incredible diversity of life.
124
Until the next Mass Extinction.
125
This is the first episode of a six-part series on mass extinctions.
126
Make sure to follow the Colossal YouTube channel for the next episode, where we're gonna go over the confusing mess of the Devonian Mass Extinction.
127
See ya!
📺 نفس القناة
✨ فيديو موصى به
C13
37 جمل
The Megatsunami That Struck the Entire Planet
IELTS PrepTOEFL PrepUniversity Students
C12
58 جمل
Listening part four (THE EXTINCTION OF THE DODO BIRD) @ieltslisteningpro.24
IELTS PrepTOEFL PrepUniversity Students
C12
47 جمل
We Found Galaxies Too Old for the Universe
IELTS PrepTOEFL PrepUniversity Students
C11
114 جمل
There's a Giant Hole In Earth's History
IELTS PrepTOEFL PrepUniversity Students
C14
204 جمل
The Insane Biology of: The Octopus
IELTS PrepTOEFL PrepUniversity Students
C111
52 جمل
The Most Gruesome Parasites – Neglected Tropical Diseases – NTDs
IELTS PrepTOEFL PrepUniversity Students
C195 جمل
Paleoworld- Loch Ness Secrets (Part 1)
IELTS PrepTOEFL PrepUniversity Students
C15
87 جمل
Why Meat is the Best Worst Thing in the World 🍔
IELTS PrepTOEFL PrepUniversity Students
C11
33 جمل
Join Kai, protect the night sky. Light pollution is hurting cultural knowledge and biodiversity
IELTS PrepTOEFL PrepUniversity Students
C13
22 جمل
How The Universe Could Destroy Life On Earth
IELTS PrepTOEFL PrepUniversity Students
C14
50 جمل
IELTS Listening Practice Test 2026 | Section 4 | Coral Reefs | Questions 31-40 | With Answers
IELTS PrepTOEFL PrepUniversity Students
عن هذه الدرسة
في هذا الفيديو، نستكشف مفهوم الانقراض الجماعي وتاريخه على كوكب الأرض. سنتعرف على كيفية تأثير التغيرات البيئية الكبرى على الأنواع المختلفة، وكيف يمكن أن تساعدنا دراسات الانقراض في فهم عالمنا اليوم وأين نتجه في المستقبل. ستتمكن من تحسين النطق باللغة الإنجليزية من خلال الاستماع إلى الحوار والتفاعل مع المصطلحات الجديدة.
المفردات والعبارات الأساسية
- انقراض: extinction
- تغير المناخ: climate change
- عصر الجليد: ice age
- حرارة عالمية: global warming
- الأنواع: species
- فترة الأوردوفيشيان: Ordovician period
- السمك: fish
- تغيرات كيميائية: chemical changes
نصائح للممارسة
لتعزيز مهاراتك في النطق وتحسين اللغة، من المفيد استخدام طريقة التظليل في الإنجليزية. حاول أن تستمع إلى الحوار في الفيديو وتكرر ما تسمعه بصوت مرتفع. يمكنك أن تبدأ ببطء ثم تزيد السرعة لتتناسب مع سرعة المتحدث. تذكر أن تنتبه للانفعالات في الصوت، وكيف يتم نطق الكلمات بشكل مختلف حسب السياق. استخدم هذه التقنيات لتسهيل تعلم الإنجليزية مع يوتيوب، ولتطوير مهاراتك في النطق باللغة الإنجليزية بشكل فعال.
القواعد في هذا الفيديو
أكثر التراكيب التي يستخدمها المتحدث، مع العبارات نفسها من الفيديو:
| التركيب | في الفيديو |
|---|---|
| المبني للمجهول be + اسم المفعول — التركيز على ما يحدث لا على من يفعله | was rocked · was frozen · were done |
| جمل الوصل who / which + جملة — معلومة إضافية عن شخص أو شيء | circulation, which can · gas, which means · weathering, which is |
| المضارع التام have/has + اسم المفعول — حدث ماضٍ ما زال له أثر الآن | have been · have identified |
ما هي تقنية التظليل الصوتي؟
التظليل الصوتي (Shadowing) تقنية تعلم لغة مدعومة علمياً، طُورت أصلاً لتدريب المترجمين الفوريين المحترفين. الطريقة بسيطة لكنها قوية: تستمع لصوت إنجليزي أصلي وتكرره فوراً بصوت عالٍ — كظل يتبع المتحدث بتأخير 1-2 ثانية. تُظهر الأبحاث تحسناً كبيراً في دقة النطق والتنغيم والإيقاع وربط الأصوات والاستماع والطلاقة.