Sahara Went from Green to Desert in a Flash
bootlegga @ Sun Apr 07, 2013 3:56 pm
$1:
From lakes and grasslands with hippos and giraffes to a vast desert, North Africa's sudden geographical transformation 5,000 years ago was one of the planet's most dramatic climate shifts.
The transformation took place nearly simultaneously across the continent's northern half, a new study finds. The results will appear in an upcoming issue of the journal Earth and Planetary Science Letters.
The findings come from analyses of dust blown west from Africa and dropped into the Atlantic Ocean. Researchers sifted through 30,000 years of dust and ocean bottom muck retrieved with ocean drilling ships. The changing levels of windblown dust in the ocean sediments provide scientists with clues to Africa's climate and how it has changed over time. Simply put, a lot of dust means drier conditions and less dust means a wetter environment.
The wet period, called the African Humid Period, started and ended suddenly, confirming previous studies by other groups, the sediments revealed. However, toward the Humid Period's end about 6,000 years ago, the dust was at about 20 percent of today's level, far less dusty than previous estimates, the study found.
The study may give scientists a better understanding of how changing dust levels relate to climate by providing inputs for climate models, David McGee, an MIT paleoclimatologist and lead study author, said in a statement. Sahara desert dust dominates modern-day ocean sediments off the African coast, and it can travel in the atmosphere all the way to North America.
McGee and his colleagues are now testing whether the dust measurements can resolve a long-standing problem: the inability of climate models to reproduce the magnitude of wet conditions in North Africa 6,000 years ago.
The transformation took place nearly simultaneously across the continent's northern half, a new study finds. The results will appear in an upcoming issue of the journal Earth and Planetary Science Letters.
The findings come from analyses of dust blown west from Africa and dropped into the Atlantic Ocean. Researchers sifted through 30,000 years of dust and ocean bottom muck retrieved with ocean drilling ships. The changing levels of windblown dust in the ocean sediments provide scientists with clues to Africa's climate and how it has changed over time. Simply put, a lot of dust means drier conditions and less dust means a wetter environment.
The wet period, called the African Humid Period, started and ended suddenly, confirming previous studies by other groups, the sediments revealed. However, toward the Humid Period's end about 6,000 years ago, the dust was at about 20 percent of today's level, far less dusty than previous estimates, the study found.
The study may give scientists a better understanding of how changing dust levels relate to climate by providing inputs for climate models, David McGee, an MIT paleoclimatologist and lead study author, said in a statement. Sahara desert dust dominates modern-day ocean sediments off the African coast, and it can travel in the atmosphere all the way to North America.
McGee and his colleagues are now testing whether the dust measurements can resolve a long-standing problem: the inability of climate models to reproduce the magnitude of wet conditions in North Africa 6,000 years ago.
http://ca.news.yahoo.com/sahara-went-gr ... 02231.html
Unsound @ Sun Apr 07, 2013 4:20 pm
Probably had something to do with developing the oil sands.
stratos @ Sun Apr 07, 2013 4:52 pm
Seen this on the T.V. a few months ago. They said it was do to climate change. Wonder how they are going to blame man for this.
raydan @ Sun Apr 07, 2013 4:53 pm
Those damn gas guzzling chariots. 
herbie @ Sun Apr 07, 2013 6:35 pm
Greenhouse gas from camel farts.
Batsy @ Mon Apr 08, 2013 4:04 am
$1:
From lakes and grasslands with hippos and giraffes to a vast desert, North Africa's sudden geographical transformation 5,000 years ago was one of the planet's most dramatic climate shifts.
It must have been all those cars and lorries and planes and factories pumping pollutants into the atmosphere.
In fact, the Sahara desert is still growing (naturally, of course). It is the size of the United States and is growing by about half a mile a year.
In total, an area of the world the size New Mexico, or Poland, is turned into desert every year, and this has been happening for a long time.
PublicAnimalNo9 @ Mon Apr 08, 2013 5:59 am
Interestingly though, the Sahara is beneficial to the rainforests in South America. All that dust usually blows westward and as it reaches altitude, attracts water droplets that fall as rain in the rainforests. There's also a specific area of the Sahara where long fossilzed marine life from when the desert was still ocean floor is now just dust. This dust also blows across the Atlantic to South America and when it falls as rain, adds nutrients to the soil.
The earth is such a friggin' awesome place, we need to spend less on space exploration and more on studying how our amazing planet works.
BartSimpson @ Mon Apr 08, 2013 8:05 am
PublicAnimalNo9 PublicAnimalNo9:
The earth is such a friggin' awesome place, we need to spend less on space exploration and more on studying how our amazing planet works.
We can and should do both. Learning about and caring for our planet is important but the future of humanity is out among the stars. Just as many of our ancestors once crossed oceans to find a new home our descendants will cross the great void of space to find their new homes. We should not deny them that opportunity.
Jonny_C @ Mon Apr 08, 2013 8:09 am
What comes to mind for me is if the climate of North Africa changed from wet to dry, there should very likely have been a corresponding shift somewhere else from dry to wet. Where is that other place?
martin14 @ Mon Apr 08, 2013 8:12 am
Jonny_C Jonny_C:
What comes to mind for me is if the climate of North Africa changed from wet to dry, there should very likely have been a corresponding shift somewhere else from dry to wet. Where is that other place?
England.
raydan @ Mon Apr 08, 2013 8:15 am
I would have said Vancouver, but England works too.
Zipperfish @ Mon Apr 08, 2013 8:38 am
PublicAnimalNo9 PublicAnimalNo9:
The earth is such a friggin' awesome place, we need to spend less on space exploration and more on studying how our amazing planet works.
Sure. You've proven yourself to be such a big propnent of earth sciences in the past.
Give yer head a shake.
N_Fiddledog @ Mon Apr 08, 2013 9:06 am
They've found hippo bones in northern Europe, and a species of crocodile in Greenland. Every once in a while a bit of glacier melts in Greenland and they find a viking village under there. So yeah, all over the world the climate changes, has changed, and will continue to change.
Zipperfish @ Mon Apr 08, 2013 9:17 am
N_Fiddledog N_Fiddledog:
They've found hippo bones in northern Europe, and a species of crocodile in Greenland. Every once in a while a bit of glacier melts in Greenland and they find a viking village under there. So yeah, all over the world the climate changes, has changed, and will continue to change.
That's just what they want you to believe.
N_Fiddledog @ Mon Apr 08, 2013 10:05 am
Zipperfish Zipperfish:
N_Fiddledog N_Fiddledog:
They've found hippo bones in northern Europe, and a species of crocodile in Greenland. Every once in a while a bit of glacier melts in Greenland and they find a viking village under there. So yeah, all over the world the climate changes, has changed, and will continue to change.
That's just what they want you to believe.
Yeah, like Exxon and the Bilderbergs are sneaking around archeological digs in Northern Europe dropping hippo bones down their pant legs, right.
