photo: nbcnews
Looking at the Sahara desert does not conjure visions of lush forests and verdant hills, but more and more evidence points to a once very green past in the vast sand expanse.
And the change from grasslands to desert was very, very fast.
That change also transformed the entire northern hemisphere of the planet. And it was very recent, as recent as 5,000 years ago, scientists believe.
Some of the findings show that sand was blown west from Africa and into the Atlantic Ocean. The layers of sediments at the bottom of the sea during a span of 30,000 years show that the climate of north Africa changed drastically over time.
The Sahara desert region had a 'wet' period, called the African Humid Period, which ended just as dramatically and swiftly as it began. The wet period seems to have ended about 5000 years ago. However, the sediments show that the level of dust at that time was only 20% of what it is today. The level of dust relate to climate change and it might give important clues on their interaction.
The study of the dust, which is now sometimes carried all the way to North America by the wind, and its measurement could unlock the puzzle of climate models that so far have been unable to reproduce the 'wet' conditions of the Sahara region that must have been in place about 6,000 years ago.
Source: Live Science 4.6.13
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