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Why and when the Sahara Desert was green: new research

phys.org

31–40 of 102 posts

Re: Why and when the Sahara Desert was green: new research

#32
post #20
post #4

Sahara could be green again in the future once the East African Rift becomes a new ocean 10 million years from now.

Would it though? The trade winds converge over central Africa, which is already quite lush, so presumably any extra moisture would just be deposited there instead of a few thousand miles to the north.

Probably yes, but I’d need to see a model to be sure. Changes to the general circulation of the oceans had massive effects on paleoclimates. Recent examples are the closing of the Panama strait, and the opening of a new strait between Australia and Antarctica.

Re: Why and when the Sahara Desert was green: new research

#33

When was this research established? I've heard about this a few years ago but when was it found that Arabia was green historically?

Periodic desertfication of the broad north African region north of the Sahel is a notion that dates back to at least the early 1980s (and probably decades before) and is based on layering in river systems and other strata evidence.

This specific research tightens up the timing and driving factors for the specific Sahara region (Libya, Egypt, Sudan) and doesn't relate to the Arabian Peninsula which is an almost seperate landmass more than three quarters surrounded by sea water.

On that landmass the Arabia Felix region (modern Yeman (mostly)) is known to have been greener in the past.

Re: Why and when the Sahara Desert was green: new research

#34

I think it was in Michael Palin's show Sahara, he's talking to some locals living in a village in the middle of the desert, and while I'm wondering why anyone would ever settle out there, the person being interviewed relayed that many more people used to live there before it became a desert. It wasn't that they moved out there, they were all that was left. Kind of post-apocalyptic. Edit: found the mention, he's talki…

Great reminder to all that we know we are effectively killing Lake Chad, but there's not much anyone is really doing about it.

[0]https://en.wikipedia.org/wiki/Lake_Chad

Re: Why and when the Sahara Desert was green: new research

#35

So with the co2 forcing function, is it possible that Canada be glaciated again And that the Sahara be green? That would fly in the face of conventional thinking which is that Canada will be temperate and the Sahara will be more arid.

The article is saying that the green Sahara coincides with periods of greater seasonal rainfall and humidity, caused by changes to the procession of the Earth and the effect that has on the seasons. It's possible that current anthropogenic climate change could make the Sahara greener, but it's also possible that it might not. In any case, the greening would probably take hundreds of years or more to happen.

Re: Why and when the Sahara Desert was green: new research

#36
post #34

I think it was in Michael Palin's show Sahara, he's talking to some locals living in a village in the middle of the desert, and while I'm wondering why anyone would ever settle out there, the person being interviewed relayed that many more people used to live there before it became a desert. It wasn't that they moved out there, they were all that was left. Kind of post-apocalyptic. Edit: found the mention, he's talki…

Great reminder to all that we know we are effectively killing Lake Chad, but there's not much anyone is really doing about it. [0] https://en.wikipedia.org/wiki/Lake_Chad

Same story for the Aral sea. https://en.m.wikipedia.org/wiki/Aral_Sea

Re: Why and when the Sahara Desert was green: new research

#37
post #31

I'm not a historian, archeologist, or any sort of relevant expert. But I've long had the pet theory that the Green Sahara is the origin of the Eden Myth. Homo Sapiens origin, lush vegetation, turns to dessert for some reason beyond our comprehension...

I dunno, I mean the myth doesn't say "Then The Lord Smote the Garden Unto Sand", it says that Eden (and the plants) persisted in the same spot as before... Humans were just being actively blocked by an angel with a flaming sword.

Re: Why and when the Sahara Desert was green: new research

#38
post #6

Somewhat off topic, but if anyone's read Sand County Almanac by Aldo Leopold, he talks about how the American Southwest, specifically Arizona, used to be green. Apparently the familiar reddish brown resulted from human impact

What’s the proposed mechanism for that? It doesn’t seem plausible to me on the surface.

I don’t know about Arizona, but apparently, parts of the great plains were dense forest that Europeans clear cut, and they simply never recovered. Also, California used to be green in the summer, but then people introduced non-native grass that grows rapidly in spring, choking out the native plants, but dies by July. It is the reason the hills are so yellow and dusty and dry.

There is some stuff along route 66 that suggests the desert was there longer than humans though. One example is the crater they used for moon landing training. It’s basically undisturbed, and is extremely old.

Re: Why and when the Sahara Desert was green: new research

#39

I think it was in Michael Palin's show Sahara, he's talking to some locals living in a village in the middle of the desert, and while I'm wondering why anyone would ever settle out there, the person being interviewed relayed that many more people used to live there before it became a desert. It wasn't that they moved out there, they were all that was left. Kind of post-apocalyptic. Edit: found the mention, he's talki…

The Earth's precession cycles driving Sahara rainfall have a period of about 23,000 years. Whatever caused deforestation there over the past 500 years likely was distinct from the Green Sahara cycles.

Re: Why and when the Sahara Desert was green: new research

#40

Carbon emissions ACCELERATED climate change. Climate change is natural. It's the ACCELERATED change that is the problem. Not enough time for species to adjust.

Carbon emissions are moving the climate into a mode it would not have entered without human intervention.

Your argument is similar to “Everyone would have died anyway; this thermonuclear winter just sped it up. Totally not humanity’s fault we live in a bunker.”

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