Did Man Change Sahara From A Lush Forest to An Arid Wasteland?

Libyan desert in Sahara. Image credits: Pinterest

For most people, the Sahara is synonymous with endless dunes and scorching, unforgiving sun, and with good reason too.

As the largest hot desert in the world, Sahara is practically the size of the United States of America and occupies roughly 31 percent of Western Africa. It is also draped in large sand seas or ergs, some of which are over 180 meters high.

Sahara
The great Sahara desert. Image credits: NASA

 

The Sahara is also home to some of the hottest spots on the planet, owing to several factors such as the perennially high position of the sun, low relative humidity, and a sore lack of rainfall and vegetation. However, the climate and topography of the Sahara wasn’t always this way.

SAHARA – A PARADISE IS LOST…

As recently as 6,000 years ago, most of the Sahara was covered by lush forests and grasslands that were dotted with sparkling lakes and diverse wildlife.

Termed as the African Humid Period, these years saw the region experiencing robust monsoons, which encouraged the growth of shrubs and grasses, and created freshwater lakes, whose beds can still be found buried under the African golden sands.

But then, things changed. In what is believed to be one of the biggest climate change shifts experienced by the planet, the Sahara went from one of the best places to live on Earth to its current dry, uninviting avatar.

DID PLANETARY MOVEMENT PLAY A ROLE?

Several scientists, including NASA’s Gavin Schmidt believe that this change in the Sahara occurred due to a change in the Earth’s orbital tilt – from the erstwhile 24.1 degrees to the current-day 23.5 degrees. This, in turn, affected the amount of solar energy received by the Earth from the sun.

This change is attributed to the various gravitational forces that are exerted by other bodies in the solar system on our home planet and occurs every 41,000 years. Certain other climate scientists, such as Dr. David Wright from Seoul University, believe that this dramatic change can be attributed to more human causes.

ANCIENT HUMANS AT FAULT

Dr. Wright claims that the Saharan desert owes its origins not to planetary wobbles or shifts in its tilt, but rather to human intervention, more specifically due to the grazing and cultivation practices of Neolithic populations. Dr. Wright compared archaeological evidences of pastoralism or animal husbandry with the spread of scrub-like vegetation in the Sahara.

The latter being an indicator of a move to a more desert-like environment, and found that the two were interconnected. At the same time that pastoral communities began to appear on the West African topography, the area also witnessed a corresponding increase in scrub-like vegetation.

As more livestock was introduced, stripping the region of its tree cover, the amount of sunlight reflecting off the Earth’s surface also began to increase. This created atmospheric conditions that were less conducive to monsoon rainfall, which, again, further contributed to desertification and vegetation loss.

As the cycle continued over the years, the entire region transformed into a giant desert that is inhabitable by human beings and animals alike.

Dr. Wright believes that drilling into the former lake beds will provide further evidence of changing vegetation patterns, which will help researchers to better understand the long-term impacts of human-induced climate change.

With more than 15 percent of the planet’s current population residing in desert-like conditions, this data will also enable scientists to determine whether or not human beings can survive in arid environments in the long term and identify those human habits that have a profound impact on surrounding habitats.

TAKE AWAY MESSAGE

We are not sure exactly sure about how Sahara came to be what we see today. However, we must acknowledge the fact that human intervention can profoundly influence ecosystems.

According to United Nations, 41.3 % of land mass is Dry lands. This is a sizeable number when we think of how this affects the issue of global food security due to shortage of arable lands. Also, more than 35 % of world population lives in these ecosystems.

Whether it is overgrazing or rampant slash and burn farming, any adverse action on our part could prove detrimental to the future generations. If there is one lesson we should learn regarding living on drylands, it is this:

If the land is stripped of vegetation, the land-atmosphere dynamics are changed. This is likely to reduce rainfall and eventually water scarcity kicks in…

and lush green fields could turn into sand bowls…

Source United Nations Science Direct

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