Home Glaciers How many ice ages has Earth had and could humans experience one?

How many ice ages has Earth had and could humans experience one?


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How many ice ages has Earth had and could humans experience one? – Mason C., 8, Hobbs, New Mexico

First of all, what is an ice age? It’s when the Earth has cold temperatures for a long time – millions to tens of millions of years – that lead to ice caps and glaciers covering large areas of its surface.

We know that the Earth has experienced at least five major ice ages. The first one happened about 2 billion years ago and lasted about 300 million years. The most recent started about 2.6 million years ago, and in fact, we’re still technically there.

So why isn’t the Earth covered in ice right now? This is because we are in a so-called “interglacial” period. In an ice age, temperatures will fluctuate between colder and warmer levels. Ice caps and glaciers melt during warmer phases, called interglacials, and expand during colder phases, called glacials.

Right now we are in the warm interglacial period of the last ice age, which began about 11,000 years ago.

What was it like during the Ice Age?

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

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

This difference may seem small, but it resulted in most of North America and Eurasia being covered by ice sheets. Earth was also much drier, and sea levels were much lower, because most of Earth’s water was trapped in ice caps. Steppes, or dry grassy plains, were common. The same was true of savannahs, or warmer grassy plains, and deserts.

Many animals from the Ice Age would be familiar to you, including brown bears, caribou and wolves. But there were also the megafauna that became extinct at the end of the Ice Age, such as mammoths, mastodons, saber-toothed cats and giant ground sloths.

There are different ideas about why these animals became extinct. The first is that humans hunted them to extinction when they came into contact with megafauna.

Wait, there were humans during the Ice Age?!

Yes, people like us lived through the Ice Age. Since our species, Homo sapiens, emerged around 300,000 years ago in Africa, we have spread all over the world.

During the Ice Age, some populations remained in Africa and did not experience the full effects of the cold. Others moved to other parts of the world, including the cold, glacial environments of Europe.

And they weren’t alone. At the start of the Ice Age, there were other hominid species – a group that includes our immediate ancestors and closest relatives – throughout Eurasia, such as the Neanderthals in Europe and the mysterious Denisovans in Asia. These two groups seem to have disappeared before the end of the Ice Age.

There are many ideas about how our species survived the Ice Age while our hominin cousins ​​did not. Some believe it has to do with our adaptability and the way we used our social and communication skills and tools. And it looks like humans didn’t retreat during the ice age. Instead, they moved into new areas.

For a long time, it was thought that humans only entered North America after the ice caps melted. But fossilized footprints found in White Sands National Park in New Mexico show humans have been in North America for at least 23,000 years – near the peak of the last ice age.

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This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/how-many-ice-ages-has-the-earth-had-and-could-humans-live-through-one-179360.