How Major Catastrophic Events Disrupt the Course of Life on Earth

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  • 0:00 Catastrophic Events
  • 0:46 Asteroid Impact
  • 3:02 Volcanic Eruption
  • 4:49 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Do you know that, smart as we are, we can be destroyed any second? History provides us with many catastrophic events that led to mass destruction and this lesson covers a couple.

Catastrophic Events

The Great Depression, World War II, and 9/11 were all, in their own way, catastrophic events in American - even world - history. They changed the course of how we have lived ever since. These events were all manmade. Nature did not create any undue hardships on our lives as a result of them. But nature has, in the past, caused catastrophic, or disastrous, events to occur right here on Earth. So much so, that it has disrupted the lives of countless creatures large and small. We'll cover two major catastrophic events in world history and their impact on Earth: one, an asteroid impact; the other, a volcanic eruption.

Asteroid Impact

Long, long ago before you, your parents, or grandparents were ever born, the Earth was in the Cretaceous period, a period in Earth's history ranging from 145.5 million years ago to 65.5 million years ago.

If we were to take a really cool field trip using a time machine back to the very tail end of this period, roughly 65 million years ago, we would be faced with a very different world. There would be lots of cone-bearing plants on land. Instead of whale and dolphin boat tours, we'd go out into the water to spot and snorkel with marine reptiles, like the mosasaurs. Instead of an African safari to watch elephants, we'd be watching and probably running away from T-rex. And we'd be gazing up at the spectacular sights of pterosaurs flying above us.

It was a different time. And we wouldn't have much time on our field trip either because, lo and behold, as we gaze up at the flying dinosaurs, we see a fireball streaking across the sky far above them. What is it? It's an asteroid streaking across the sky, roughly 6 miles in diameter. It hits an area now known as the Yucatan peninsula of Mexico, and this impact marks the end of the Cretaceous period.

While the explosive impact of the asteroid obviously obliterated everything around it, the impact itself didn't kill as much life on Earth as its consequences did. The asteroid likely sparked huge forest fires that killed many creatures. The smoke and dust from the fires and impact at first may have blocked sunlight and caused the Earth to cool, but then the CO2 released by the impact and fires caused the Earth to heat up as a result of the 'greenhouse effect'.

All of this caused about 80% of all of the world's species of animals to go extinct, including essentially all of the dinosaurs. Many plant species disappeared as well. While this may seem sad that T-rex is gone, do remember that this extinction event is what paved the way for mammals, like ourselves, to make a place for ourselves in this world.

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