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Study shows the Sahara swung between lush and desert conditions every 20,000 years...
phys.org ^ | January 2, 2019 by | Jennifer Chu, Massachusetts Institute of Technology

Posted on 01/03/2019 7:16:04 AM PST by BenLurkin

[R]esearchers at MIT have analyzed dust deposited off the coast of west Africa over the last 240,000 years, and found that the Sahara, and North Africa in general, has swung between wet and dry climates every 20,000 years. They say that this climatic pendulum is mainly driven by changes to the Earth's axis as the planet orbits the sun, which in turn affect the distribution of sunlight between seasons—every 20,000 years, the Earth swings from more sunlight in summer to less, and back again.

For North Africa, it is likely that, when the Earth is tilted to receive maximum summer sunlight with each orbit around the sun, this increased solar flux intensifies the region's monsoon activity, which in turn makes for a wetter, "greener" Sahara. When the planet's axis swings toward an angle that reduces the amount of incoming summer sunlight, monsoon activity weakens, producing a drier climate similar to what we see today.

Sahara shifts between wet and dry periods every 100,000 years—a geologic beat that scientists have linked to the Earth's ice age cycles, which seem to also come and go every 100,000 years. Layers with a larger fraction of dust seem to coincide with periods when the Earth is covered in ice, whereas less dusty layers appear during interglacial periods, such as today, when ice has largely receded.

McGee says this interpretation of the sediment cores chafes against climate models, which show that Saharan climate should be driven by the region's monsoon season, the strength of which is determined by the tilt of the Earth's axis and the amount of sunlight that can fuel monsoons in the summer.

(Excerpt) Read more at phys.org ...


TOPICS: Science
KEYWORDS: sahara; saharadesert
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1 posted on 01/03/2019 7:16:04 AM PST by BenLurkin
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To: BenLurkin

So it was a heavy drinker?......................


2 posted on 01/03/2019 7:18:27 AM PST by Red Badger (We are headed for a Civil War. It won't be nice like the last one....................)
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To: BenLurkin

So even Fred Flintstone’s carbon free vehicle couldn’t prevent climate change


3 posted on 01/03/2019 7:18:49 AM PST by FatherofFive (Islam is EVIL and needs to be eradicated)
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To: BenLurkin

but, but, but....we have to shut down our economy while letting others grow to stop climate change!


4 posted on 01/03/2019 7:18:53 AM PST by ealgeone
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To: BenLurkin

This suggestion has been out there for a number of years, but with limited evidence. Other bits to this include a massive farming belt that existed around Botswana and Namibia, with a massive irrigation system (canal system) which was fed by healthy rainfall throughout the year (all more than 10,000 years ago).


5 posted on 01/03/2019 7:20:31 AM PST by pepsionice
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To: BenLurkin

It’s almost like weather/climate is cyclical.


6 posted on 01/03/2019 7:24:46 AM PST by ConservaTexan (February 6, 1911)
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To: BenLurkin

What in the Wide Wide World of Sports is going on here!
The SUN!
Ain’t nobody no how said a durned thing about the SUN!
We’ve been told its the SUV’s, coal power plants and cow farts making the weather go winky wonky.

I’m going back to bed.
Someone wake me up when the world makes sense again.


7 posted on 01/03/2019 7:27:53 AM PST by oldvirginian ( Buckle up kids, rough road ahead.)
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To: SunkenCiv

*ping*


8 posted on 01/03/2019 7:32:18 AM PST by fieldmarshaldj ("It's Slappin' Time !")
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To: BenLurkin

McGee says this interpretation of the sediment cores chafes against climate models,


chafes?


9 posted on 01/03/2019 7:38:53 AM PST by PeterPrinciple (Thinking Caps are no longer being issued but there must be a warehouse full of them somewhere.)
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To: PeterPrinciple

http://www.lerctr.org/~transit/healy/wacky.wav


10 posted on 01/03/2019 7:40:35 AM PST by BenLurkin (The above is not a statement of fact. It is either satire or opinion. Or both.)
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To: ConservaTexan
It’s almost like weather/climate is cyclical.

Hush yo' mouth! Don't you care about the chilrun? ... and dolphins? ... and baby polar bears?

11 posted on 01/03/2019 7:44:38 AM PST by BwanaNdege
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To: BenLurkin

Saw this earlier, thank you for posting it, right up my alley.

I would venture to say that this tilting would also move the equator and tropic rain forest zones to a new latitude.


12 posted on 01/03/2019 7:46:10 AM PST by Openurmind
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To: BenLurkin
every 20,000 years, the Earth swings from more sunlight in summer to less, and back again.

WOW, auto exhaust and manufacturing has been doing this even way back when from man made pollution?

13 posted on 01/03/2019 7:48:49 AM PST by 1Old Pro
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To: BenLurkin

As I have been saying... Hot is good, cold is bad.
The Sahara was a luscious verdant jungle when it was hotter than now, and becomes a desert as it cools down, as it has.
All this global warming efforts BS is just making it worse.

Rev up those SUV’s, start those wood stoves! Put additives in the feed to make cows fart more! We need more CO2 and we need more heat.


14 posted on 01/03/2019 7:51:44 AM PST by Toughluck_freeper
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To: BenLurkin
Earth's Shifting Crust: A Key To Some Basic Problems Of Earth Science

by Charles Hapgood

forward by Albert Einstein


ML/NJ

15 posted on 01/03/2019 7:52:31 AM PST by ml/nj (.)
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To: BenLurkin

So we just need to maintain the tilt of the earth.


16 posted on 01/03/2019 7:52:33 AM PST by DannyTN
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To: BenLurkin
every 20,000 years, the Earth swings from more sunlight in summer to less,

Daylight savings time could have stopped that.....

17 posted on 01/03/2019 7:53:14 AM PST by Hot Tabasco
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To: DannyTN

Or find a way to sell tilt credits.


18 posted on 01/03/2019 7:55:43 AM PST by BenLurkin (The above is not a statement of fact. It is either satire or opinion. Or both.)
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To: BenLurkin

IOW, in 20,000 years the libs will be wringing their hands over globull cooling.


19 posted on 01/03/2019 7:58:38 AM PST by bgill (CDC site, "We don't know how people are infected with Ebola.")
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To: BenLurkin
"Or find a way to sell tilt credits."

Ooooh, I could be rich. I just need to put together a movie with 50 non-related emotional appeals and a hockey puck graph (already discredited is okay).

20 posted on 01/03/2019 8:00:35 AM PST by DannyTN
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