Yes! Only 11,000 years ago, the solar intensity over the Sahara was 7% greater (Milankovitch, natch!) which caused about 10% more convection of air over land… from the humid Mediterranean! That’s just a 10% boost, but it was enough to cross a ‘threshold’ of humidity, when clouds can actually form, and rain can actually fall. There’s still moisture above the desert—it’s just never dense enough to come back to Earth!
So, the Sahara got 10% more moisture, which let a few plants grow… and plants are darker than desert rock, so they created a steeper gradient of heating every morning—the green inland regions got hot and humid fast, air rising, which pulled MORE sea-breeze and humidity deep inland! It’s a feedback loop, which was how the Sahara was green for thousands of years, covered in laurel forests and grasslands, in cycles stretching back tens of thousands of years.
The Point: if we add just a little bit more water, we can get a feedback loop, just like our geological past. We’re on the threshold of rain-formation humidity.
Yes! Only 11,000 years ago, the solar intensity over the Sahara was 7% greater (Milankovitch, natch!) which caused about 10% more convection of air over land… from the humid Mediterranean! That’s just a 10% boost, but it was enough to cross a ‘threshold’ of humidity, when clouds can actually form, and rain can actually fall. There’s still moisture above the desert—it’s just never dense enough to come back to Earth!
So, the Sahara got 10% more moisture, which let a few plants grow… and plants are darker than desert rock, so they created a steeper gradient of heating every morning—the green inland regions got hot and humid fast, air rising, which pulled MORE sea-breeze and humidity deep inland! It’s a feedback loop, which was how the Sahara was green for thousands of years, covered in laurel forests and grasslands, in cycles stretching back tens of thousands of years.
The Point: if we add just a little bit more water, we can get a feedback loop, just like our geological past. We’re on the threshold of rain-formation humidity.