Sahara desert used to be green
9,000,000 square kilometers of sand and rocks - that's what the Sahara desert is. Second only in lifelessness to the Antarctica. To better understand it's size, imagine this - it's larger than Australia. And as if that wasn't enough, the Sahara is expanding! By approximately 48 kilometers per year, towards the south, the tropical savannas. But the desert isn't as lifeless as it may seem. Many species of animals live by the Nile, which is the heart of Sahara. Other than that, only occasional oases can offer some kind of refuge from the ruthless desert. But when did all these oases appear? Here's the catch - Sahara wasn't always a desert. In fact, around 120 000 years ago, the desert was thriving.
Rivers ran through the desert and grassy plains loomed along them, probably housing thousands of species of various critters. But how was all of this found out? Scientists from MARUM – Center for Marine Environmental Research in Bremen and the Alfred-Wegener-Institute in Bremerhaven, were studying the coast of northwest Africa, hoping to find out how the hydrological cycle changed over the years. Over the last 120 000 years, there were three periods of particular interest. During these periods, particles of the land were transported by water and not by wind, as it is usual in the desert. This lead the scientists to think that once rivers were flowing through the Sahara. Computer simulation proved this, showing three periods of Sahara having almost full grass coverage. Besides, it calculated that only a minimal increase of the Sahara's current 2 to 10 centimeters of rain per year would be sufficient to cover the desert with grass.
It is not known whether Sahara will ever be green again. And I'm sure scientists know more than me, but couldn't have those particles been brought by a really huge tsunami, rather than a river? One thing is certain, though. If Sahara was grassy, it would soon be exploited and the world food prices would decrease, putting an end to global hunger... i think.
0 comments:
Post a Comment