In this blog I advance the idea that the Sahara desert might find itself in the position of saving the world. In the process, the Sahara would become a vegetated green area as it once was thousands of years ago. It would also become a global leader in the production of energy, that is, green energy, as well as food, all at a modest cost to the world.
Twelve thousand years ago the Sahara Desert was a green, lush tropical habitat made up of tropical grasslands, woodlands and tropical forests, as well as extensive wetlands (marked in blue on the map below) that provided habitats for enormous flocks of birds, fish in abundance, indigenous grains and herds of wild game.
A radar scan by NASA and a topographic review in 2010 by the National Academy of Sciences,
revealed that this part of northern Africa had once been an extraordinary
region with large, interlinked waterways. Thus, the long-standing mystery of
how early man, fish and other animals moved into, around and across the ancient Green Sahara
was finally solved.
The early prehistoric residents were hunter/gatherers so overburdened by the natural production of this green landscape that they only turned to pastoralism and farming when living conditions became difficult. Which happened during a period of drying that occurred about 5,000 years ago when the Sahara Desert was formed.
All of that was history, as I’ve been told many
times. Nowadays people are more concerned with things like Global Climate
Change, a phenomenon I had to explain whenever it raised its ugly head. In
recent years people’s attitudes have changed further and now they want to know
how I as an ecologist could make it disappear. I had no idea how though I
already knew enough about the ancient Green Sahara that flourished thousands of
years ago to know what it would look like if the world were to succeed in greening
up the same desert today.
I happened recently to read a research paper by a
scientist from a Beijing university visiting in the USA. Prof. Yan Li, a
climatologist, pointed out that some parts of the world were ideally suited to
wind and solar farms. One area he identified as perfect was the world’s largest
desert, the Sahara. He went on to say that if and when a large enough portion
of the Sahara were taken up by such farms, the concentration would be enough to
effect global weather, bringing rain in significant amounts to completely green
up the region.
The effect first described by Prof. Li was that
when the size of wind and solar farms reach 20 percent of the total area of the
Sahara, it will trigger a feedback loop, also referred to as a ‘tipping point.’
Heat emitted by the darker solar panels (compared to the highly reflective
desert soil) creates a steep temperature difference between the land and the
surrounding oceans, that and the wind turbines will ultimately lower surface
air pressure and cause moist air to rise and condense into raindrops.
Would such a thing ever happen? I realized that many climatologists thought
the idea was farfetched, the area concerned was much too large and the chances
too slim. Such a tipping point would never be reached.
Then came the flash floods in Dubai in April of this year when Dubai received nearly two years’ worth of rain in just one day! Videos appeared on the internet showing enormous amounts of water rushing through streets and boulevards carrying all before it, cars, trees, kiosks all tumbling along. As further proof that rains of unheard of intensity could occur in the desert came the flash flooding in May that devastated parts of Saudi Arabia. The internet again came alive showing hundreds of cars being swept away by the deluge as roads were submerged amid the torrential downpours that swept this desert Kingdom.
To my mind came the picture of the catastrophic flooding in
Libya in September the year previous when a storm that had caused torrential
rain throughout the Mediterranean brought extreme rainfall across northeastern
Libya. In one of the driest countries on earth 16 inches of rain falling in one
day caused a dam to collapse and partially destroyed the city of Derna. Estimates
for the number of casualties ranged from 5,900 to 20,000 people.
To top it off we were bombarded by newscasts in September of
this year showing rainstorms that lasted a month and swept across the Sahara Desert leaving
behind rain that flooded streets, alleyways, highways and farms.
Some of this was foretold and all these events were ascribed
to global climate change. It made me think again that the Green Sahara tipping
point may not be as radical as it first appeared. If Mother Nature was so
easily brushed aside by man-made climate change and forced to stand by while
torrential rains fell in many of the world’s most arid countries, what would
prevent humans from nudging the tipping point in the Sahara closer to reality?
Could 20 percent of the Sahara be covered by
solar panels in order to reach the tipping point? Obviously donors and
international investors are now standing by trying to size up the investment
and development opportunities in solar farms in the Sahara. The surface of the
Sahara would in some ways even seem to encourage huge undertakings in solar energy in
that it consists of rocky hamada (stone plateaus) or desert soil hardened into
a crust-like pavement that would make fine supports for solar panels and wind towers.
Then reality set in.
The Sahara is huge, almost exactly the size of the
United States. Twenty percent of the Sahara could be defined by the area of
Texas, Oklahoma, Kansas, Nebraska, Missouri, Arkansas, Louisiana and
Mississippi. Covering such a surface with solar panels would be beyond belief.
I reluctantly put the idea aside and decided along
with many others that the Sahara would have to wait 10,000 more years for the
next interplanetary event that would cause variations in Earth's orbit and
change the weather patterns in northern Africa that would initiate the next Green Sahara.
As I pushed these thoughts from my mind I suddenly
recalled that there was still one driving force that could not wait.
It happens that when people look up the population
of the Sahara on the internet they are often told it is about 2.5 million,
which is the number of people inhabiting the arid desert portions of the
Sahara, which leaves out the Nile Valley, excluded on grounds that its
floodplain is watered by the Nile River and thus lies outside desert terrain.
The problem is, however, that the people of the
Nile Valley and especially those of the largest city in Africa, Cairo, have
more and more encroached on the Sahara for their food and water needs. Both of
these elements, water in the Nile and the arable land in the desert region of
Egypt have reached their limits. In fact today it is obvious that Cairo, whose
residents have become dependent on the Sahara for their existence, not only
would welcome a new Green Sahara, their 10 millions now see it as their only
recourse. Pressure also comes from the
burgeoning populations of the Nile Delta and the Nile River Valley where an
additional 100 million people live, many of whom are looking forward to the
future when they will be farming their share of the Sahara.
Leaving aside the seemingly impossible task of
financing, building and operating solar and wind farms on twenty percent of the
Sahara, how can the tipping point be reached in a sustainable, cost effective
manner, within a reasonable period of time, in order to save those present and
future generations dependent on the resources of the Sahara, people who, like
the Cairenes, because of an exploding population and the increasingly negative
effects of climate change, are running out of land, water and time?
If the tipping point were reached in the Sahara not only would Cairo and the deserts of Egypt be affected, but large climatic changes would evolve that would change the carbon balance of the world itself.
That is the subject of my new book, The New Green Sahara to be published by
Rowman & Littlefield in the USA and by Bloomsbury in UK in the fall of 2025.
Future blogs on this site will discuss what options are available that could be used to turn the Sahara green, and how changes in climate due
to the Greenhouse Gas effect are already evolving that may achieve this whether we like it or not.
Stay tuned.
