The Sahara Desert Was Once Green?! The Shocking Past and Cosmic Climate Cycle.

What’s up, everyone?

Today, I want to talk about the past of the Sahara Desert and climate change. While the Sahara is known as the world’s largest desert now, it was actually a fertile, green land just a few thousand years ago. Let’s dive into this mind-blowing fact and the cosmic climate cycle behind it.

Evidence the Sahara Was Once Green

There are a few pieces of evidence showing the Sahara was green in the past:

1. Discovery of Petroglyphs (Rock Carvings)

In 1850, the German explorer Heinrich Barth discovered petroglyphs in the Sahara. They depicted animals like giraffes, hippos, and crocodiles. For these animals to live, they need grasslands and watering holes. So the Sahara back then couldn’t have been a desert – it had to be a green environment.

2. Dust Analysis

Dr. David McGee from MIT analyzed layers of dust piled up on the west side of Africa. He found that from around 12,000 to 5,000 years ago, dust levels were extremely low. This means the Sahara then was humid with vegetation growing, so less sand was being kicked up into dust storms. The layers even contained pollen from plants that don’t grow in deserts.

3. Linguistic Evidence

In West Africa’s Mali and East Africa’s Ethiopia, completely different languages are spoken. But specific words, like the name for hippos, are eerily similar between them. Some linguists think this hints that the ancestors who named hippos lived together before desertification split them apart east and west.

4. Biological Remains from the Sahara

In the Tenere Desert in the southern Sahara, remains of crocodiles, hippos, and huge Nile fish have been found. Along with fishing hooks and hunting tools, this shows people lived off the land through fishing and hunting back then.

From this evidence, we can see the Sahara was a lush, green land for around 10,000 years from 12,000 to 5,000 years ago.

What the Green Sahara Was Like

So what was the environment like when the Sahara was green?

Recent research shows there was a massive lake up to 160m deep and around 350,000 sq km in area back then. That’s about the same size as the Caspian Sea, the current largest lake at 370,000 sq km.

Trees covered the land, with giraffes, hippos, crocodiles and more roaming about. The Sahara’s inhabitants lived off this abundance through fishing and hunting.

However, around 5,000 years ago, things took a drastic turn. Animal remains dropped by 40%, indicating desertification was starting to kick in.

The Milankovitch Cycles: Causing Deserts and Green Periods

So why did the green Sahara turn to desert? The answer lies in a cosmic climate cycle.

The Earth’s axis is tilted at around 23.4 degrees as it spins. But this tilt slowly traces a circular cone shape over 26,000 years in what’s called the “Milankovitch Cycles.” This cycle shifts when the Earth is closest to the Sun.

When the Sahara was green, the Earth’s axis was tilted in the opposite direction from now. The Northern Hemisphere got 4–8% more solar energy, causing intense monsoon winds and heavy rains around the Sahara. This humid climate allowed grasslands and lakes to form.

Now in the opposite cycle phase, the Sahara has become an arid desert again. But in another 26,000 years, it may revert to being green.

In fact, over the past 8 million years, the Sahara has greened up about 230 times already. As long as the Milankovitch Cycles continue, the Sahara will keep oscillating between desert and green phases periodically.

How the Sahara’s Climate Shift Impacts the World

The Sahara’s climate shifts don’t just affect that region though.

Dust storms can carry Saharan sand across the Atlantic to rain down on Central and South America. This dust is rich in phosphorus, a crucial nutrient for plant growth. So when the Sahara is dry and dusty, it essentially fertilizes the Amazon rainforest.

But if the Sahara goes through a wet, green phase with less dust, the Amazon could get phosphorus-starved and the jungle may start disappearing.

It’s crazy how the climates on opposite sides of the globe are interconnected like this – the fate of the Amazon depends partly on the Sahara’s climate cycles.

In Closing

The evidence from petroglyphs, dust analysis, linguistics, and fossil remains clearly shows the Sahara was once green. This shocking transformation was driven by the Milankovitch Cycles, a cosmic climate oscillation.

Earth’s climate involves a delicately balanced web of factors influencing each other, like the Saharan dust nourishing the Amazon from thousands of miles away.

While human activity is impacting climate change, it’s also a natural phenomenon operating on a cosmic scale. We’re all part of this magnificent living planet, so it’s crucial we’re conscious about preserving our environment.

Alright, that’s all from me today! Let me know if you have any other questions about the Green Sahara in the comments below.