Desert Planting Part 1. One-Fifth of the Earth's Arable Land is in the Sahara

 

(Part 1 can be found here  )

To cultivate the entire Sahara, about 250 times more desalinated water than what is currently produced globally would be required. However, the process could start along coasts and rivers, gradually expanding as humidity increases and new weather systems develop, leading to more rainfall.

Arable land will not run out—the only requirement is desalination, powered by simple solar collectors, solar panels, and other energy sources.

Increased humidity would also make it more profitable to extract water from the air, so a combination of methods is needed for both water production and energy supply.

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Question to AI:

How much water would need to be desalinated to make the Sahara fertile, and how would the increase in humidity create new weather systems contributing to rainfall?

ChatGPT replied:

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Making the Sahara Green Through Desalination

1. How Much Water is Needed?

The Sahara covers approximately 9.2 million km², about the same size as the U.S. or China.

• Irrigation level required: 500–1,500 mm of rainfall per year (depending on vegetation type).
• Total water volume needed (assuming 1,000 mm/year):

$$9.2 \text{ million km}^2 = 9.2 \times 10^{12} \text{ m}^2$$ $$9.2 \times 10^{12} \text{ m}^2 \times 1 \text{ m} = 9.2 \times 10^{12} \text{ m}^3 \text{ of water per year}$$

How Does This Compare to Current Water Production?

The global desalination capacity today is about 100 million m³ per day, which equals:

$$3.65 \times 10^{10} \text{ m}^3 \text{ per year}$$

To irrigate the entire Sahara, we would need about 250 times this amount, requiring gigantic desalination plants powered by renewable energy.

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2. Can New Weather Systems Be Created Through Increased Humidity?

Yes! If the Sahara received significant irrigation, it would alter the regional climate and increase precipitation through several mechanisms:

A. Evaporation and Precipitation

Moisture would evaporate from the ground and plants (evapotranspiration), increasing air humidity and leading to cloud formation and rainfall.

B. Monsoon Reinforcement

The North African monsoon winds are influenced by temperature contrasts between land and sea. Greening the Sahara could reduce these contrasts, potentially leading to increased rainfall in the Sahara, the Sahel region, and even parts of Europe.

C. Reduction of Dust Storms

The Sahara is currently one of the world's largest sources of dust, affecting weather patterns across the globe. Vegetation would reduce dust storms, leading to improved air quality and ecosystem stability.

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3. Is This Realistic?

The biggest challenges are energy and infrastructure to support large-scale desalination. However, solutions exist:

✅ Solar energy – The Sahara has some of the highest solar energy potential on Earth.
✅ Cheaper desalination technology – New low-energy desalination methods are under development.
✅ Large-scale reforestation projects – With proper planning, a fertile landscape could be created within 50–100 years.

An alternative realistic approach would be to start small-scale, by greening coastal areas and riverbeds, gradually expanding as climate conditions improve.