How many ice ages has the Earth lived, and can humans live during one? – Conversation

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How many ice ages has the Earth lived, and can humans live during one? – Mason C, 8 years old, Hobbs, New Mexico

First, what is a file ice Age? When the Earth’s temperature is cold for a prolonged period – millions to tens of millions of years – it leads to ice sheets and glaciers covering large areas of its surface.

We know that the Earth has At least five major ice ages. The first occurred about 2 billion years ago and lasted about 300 million years. The last one started about 2.6 million years ago, and in fact, we’re technically still at it.

So why isn’t ice covering the Earth now? That’s because we are in a period known as the “Ice Age”. In the Ice Age, temperatures will swing between cooler and warmer levels. Ice sheets and glaciers melt during the warmer phases, called glacials, and expand during the colder phases, called glacials.

We are now in the most recent warm glacial period of the Ice Age, which began about 11,000 years ago.

Earth’s climate goes through cycles of warming and cooling that are affected by gases in the atmosphere and changes in its orbit around the sun.

How was it during the Ice Age?

When most people talk about the “ice age,” they are usually referring to the last ice age, which began about 115,000 years ago and ended about 11,000 years ago with the start of the current ice period.

During that time, the planet was much cooler than it is now. At its peak, when ice sheets covered most of North America, the average global temperature was roughly 46 degrees Fahrenheit (8 degrees Celsius). That’s 11 degrees Fahrenheit (6 degrees Celsius) colder than the global annual average today.

This difference may not seem like much, but it did cover most of North America and Eurasia with ice sheets. The land was also drier, and Sea level was much lowerBecause most of the Earth’s water was trapped in ice sheets. steppe, or dry grassy plains, were common. so it was savannaor warm grassy plains and deserts.

many Animals Existing During the Ice Age It will be familiar to you, including brown bears, wolves, and caribou. But there were also megafauna that became extinct at the end of the Ice Age, such as Mammoths, mastodons, saber-toothed cats And the Giant ground sloth.

There are different ideas about Why did these animals become extinct?. One is that humans chased them until they became extinct when they came into contact with megafauna.

Scientists and workers gather around the jawbone and horns protruding from the ground.

Excavation of a pine skeleton at Burning Tree Golf Course in Heath, Ohio, December 1989. The skeleton, found by workers digging a pond, is 90% to 95% complete and more than 11,000 years old.
James St. John / FlickrAnd the CC BY

Hey, there were humans in the Ice Age?!

Yes, people like us lived in the Ice Age. Since our human race, sane manAnd the It appeared about 300,000 years ago in AfricaWe have spread all over the world.

During the Ice Age, some populations remained in Africa and were not exposed to the full effects of the cold. Others have moved to other parts of the world, including the cold, icy environments of Europe.

And they weren’t alone. At the beginning of the Ice Age, there were other types of hominins – a group that includes our direct ancestors and our closest relatives – throughout Eurasia, such as Neanderthals In Europe and the mystery Denisovans In Asia. These two groups seem to have become extinct before the end of the Ice Age.

There are a lot of ideas about how our species survived the Ice Age when our hominin cousins ​​didn’t. Some think it has to do with how adaptive we are and how we are Use our social and communication skills and tools. It seems that humans did not burrow during the Ice Age. Instead they moved to new areas.

For a long time it was believed that humans only entered North America after the ice sheets began to melt. But petrified footprints found in White Sands National Park In New Mexico they show that humans were in North America at least 23,000 years ago – near the peak of the last Ice Age.


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