Summary

The Sahara Desert is home to ancient history that no one generally thinks about. The ancient people, animals, and environment all left remains that we now study today. The Sahara is not well known to be connected with luscious greens and water home to many animals, but it used to be like that, and in the years to come is on its way to support that habitat again. Studying theses remains allows us to learn in depth of the history of the Sahara Desert and how its landscape was drastically different than it is today.

Why Watch This Video?

Would you like to understand how a vast area can have a complete environmental and climatic change?

Has the evolving environment of the Sahara Desert left you confused of how that can happen?

Have you ever thought about ancient hieroglyphics and how they can be applied to discover how today’s environment is?

Key Terms

Ancient artists are the people who documented their environment with images on rock walls. Those images are studied by scientists today.

Paleoclimatologists study previous climates and environments and can help compare how the Earth’s environment has changed throughout its history.

Planetary scale means events that happen on a large scale to Earth as a whole.

Loose Ends

Someone might still be confused about what exactly the environment went through to create these changes of the Sahara. The answer begins with the orbit changing, which they explain, but then it doesn’t completely explain the environment after that. What did happen was the environment got warmer and windier and brought rain over. This small change in the climate created a wetland over time.

Geologists discovering and proving how the Sahara was green could be expanded on more than what they covered in the video. They took many samples throughout Northern Africa which gave them a lot of evidence to define why the Sahara was green.

They talked about changing orbit a lot, and I think a loose end on this is how the changing orbit creates a dry environment. Earth’s orbit changes from more circular to less circular, but Earth also tilts back and forth on its axis, and also wobbles as it rotates. All of these affect how directly sunlight hits Earth’s higher latitudes, and that triggers changes in climate. In this case, the wobbling resulted in warming, and warmer air can hold more moisture, ultimately leading to more precipitation in some areas.

Clarification about “orbital change.”

Hi, Editor here. The term “orbital change” is used throughout the video, but as mentioned above, the changes are both in how Earth orbits the sun, and how it rotates on its axis. Changes in the actual orbit affect climate, but on much longer timescales. The key forcing for the Sahara has to do with rotation. To be consistent with the video, however, “orbital change” is used without distinction in these resources.

Self-Test Questions

1. What do geologists call the wet period causing the Sahara to create a new environment?

1. African wet period
2. Sahara humid period
3. African humid period
4. African wet years

2. What did geologists measure to tell how dry the Sahara was?

1. Dust flux blown off of Africa
2. How much sand is in the desert today
3. The chemical composition of desert sand
4. The metal content of ocean sediments

3. What is the main driver for turning the Sahara green?

1. Sand drifting away from the Sahara region
2. Changes in Earth’s orbit
3. Humans settling
4. Animals moving

4. What is the cycle called that creates moisture in the African continent?

1. African rainfalls
2. African heavy rain
3. Annual monsoon
4. African monsoon

5. What is a land’s albedo?

1. The amount of precipitation it receives annually
2. The amount of solar radiation it reflects
3. The amount of life it can sustain
4. The amount of geological discoveries on the land

Answers

1. The correct answer is c) African humid period. The African Humid period is a crucial time in the Sahara’s history and served a main factor as to why it is green.

2. The correct answer is a) dust flux. Dust is blown off of the African continent and into the Atlantic Ocean, and accumulates on the ocean floor. When the climate is drier there is more dust, so geologists can use changes in the amount of dust deposited over time to tell how wet or dry the climate was.

3. The correct answer is b) Changes in Earth’s orbit. Climate change occurred because of how Earth wobbling as it rotates on its axis alters how directly energy from the sun reaches different locations on Earth’s surface.

4. The correct answer is d) African Monsoon. This is annual precipitation Africa sees, however certain years get more or less.

5. The correct answer is b) solar radiation reflected. The less radiation reflected, the more a surface is warmed by the solar energy hitting it.