[HN Gopher] Why and when the Sahara Desert was green: new research
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Why and when the Sahara Desert was green: new research
Author : PaulHoule
Score : 56 points
Date : 2023-09-18 16:54 UTC (6 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| theironhammer wrote:
| 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.
| [deleted]
| alephxyz wrote:
| Even natural climate changes can be problematic, such as drier
| climates precipitating the fall of the Roman empire or the late
| bronze age collapse.
| onlyrealcuzzo wrote:
| Or The Samalas eruption - which is believed to have caused
| the Little Ice Age - and killed 90% of Europeans & North
| Americans at the time (55M people).
|
| I imagine many millions of large mammals and birds and
| insects also died.
| hinkley wrote:
| See also the Year Without Summer, 1816.
|
| Apparently Frankenstein and Dracula were both born that
| 'summer' at one of Byron's gatherings. Something to pass
| the time indoors.
| bjelkeman-again wrote:
| Meteor strikes are also natural. That doesn't mean they are
| desirable.
| mullingitover wrote:
| Surprised there's no mention of Sahara Pump Theory[1] in this
| article.
|
| [1] https://en.wikipedia.org/wiki/Sahara_pump_theory
| jackconsidine wrote:
| 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
| PaulHoule wrote:
| I went to school in Socorro, NM which was very brown on a dry
| year and pretty green on a wet year and my understanding is
| that it was a pretty grassland before white folks showed up but
| overgrazing caused the creosote bush to move in.
|
| If you go up the hills to the plains of San Augustin where the
| VLA radio telescope that is around 7000 feet in elevation and I
| think a bit cooler and wetter and that is a very pretty
| grassland where you see big herds of antelope grazing and you
| might think you were in Africa.
| OfSanguineFire wrote:
| Considering that there are archaeological sites in the
| American Southwest that are posited to have been abandoned
| due to the disappearance of their water supply, it is hard to
| blame all the aridness on "white folks". Moreover, when I
| cycled through the Anza-Borego State Park in California,
| several of the information boards discussed how hardscrabble
| the existence of the Native American peoples in this area
| was, because it was already very much desert and required
| special strategies to survive.
| xhkkffbf wrote:
| This is a solid point. I was at Mesa Verde, the national
| park with the cliff dwellings. Apparently the people who
| lived there just up and left, well before Columbus showed
| up on the other side of the continent. One theory is that
| the current Hopi people are their descendants.
|
| It's pretty clear that bad things happen, even when white
| people aren't around.
| AlotOfReading wrote:
| It's not really a "theory" as anyone normal uses that
| term. We know beyond any reasonable doubt that there's
| significant genetic, cultural, and political ancestry
| tying modern Puebloan groups to the the people who
| inhabited Mesa Verde (and other earlier pueblos). "Most"
| went east to the Rio Grande area, but plenty went west
| too. Some Hopi ancestry also comes from other groups to
| the north, west and south (into modern Mexico) where
| Puebloan groups no longer exist.
|
| With that said, Spanish and American colonization of the
| Southwest has _radically_ changed the landscape. Much of
| what 's now low brush used to be substantially more
| vegetated, similar to organ pipe national monument.
| Mesquite was rare outside intentional cultivation. It's
| actually an invasive species from the separate Chihuahuan
| deserts in Texas that was spread alongside cattle.
| Another fun fact is that prior to colonization, no part
| of AZ+NM was more than a day's walk from water (~20mi),
| which was important to long distance travel and later the
| Apache wars. That's no longer true due to groundwater
| depletion.
| OfSanguineFire wrote:
| Do you have a citation on mesquite spreading from Texas
| with cattle? I ask because the aforementioned information
| boards in the Anza-Borrego State Park speak of the local
| Native American population consuming mesquite, and
| Wikipedia, too, says the same about those Cahuilla people
| of southern California. From what I gather, it is only
| certain species that have later been invasive?
| [deleted]
| slashdev wrote:
| What's the proposed mechanism for that? It doesn't seem
| plausible to me on the surface.
| xhkkffbf wrote:
| I've heard about some efforts to regreen the desert by careful
| planting and geoforming. Anyone know anything about this? It
| would be cool if it could work, even partially.
| daneel_w wrote:
| There are projects going on in both China and on the African
| continent. Search for "Great Green Wall".
| seanmcdirmid wrote:
| China has gone through various tries of this for the last
| couple of decades. The first tries failed horribly because of
| lack of water and they sent the wrong trees to be planted for
| the ecology they were going into. I'm not sure how their
| current try is going, we will just have to see when/if the
| dust storms stop coming in the spring.
| mycall wrote:
| Sahara could be green again in the future once the East African
| Rift becomes a new ocean 10 million years from now.
| oh_sigh wrote:
| 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.
| [deleted]
| skymast wrote:
| [dead]
| monlockandkey wrote:
| When was this research established? I've heard about this a few
| years ago but when was it found that Arabia was green
| historically?
| kefabean wrote:
| It obviously doesn't cover the why of Sahara's greening, but for
| anyone who has access to BBC iPlayer, the following programme [1]
| has a nice summary of humanity's journey out of Africa.
|
| It's amazing that the majority of the world's population is
| descended from the couple of hundred individuals that left during
| one of these greening periods.
|
| [1] https://www.bbc.co.uk/iplayer/episode/b00kfqps/the-
| incredibl...
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