OSLO (Reuters) – The once-green Sahara turned to desert over thousands of years rather than in an abrupt shift as previously believed, according to a study on Thursday that may help understanding of future climate changes.

And there are now signs of a tiny shift back towards greener conditions in parts of the Sahara, apparently because of global warming, said the lead author of the report about the desert’s history published in the journal Science.

The study of ancient pollen, spores and aquatic organisms in sediments in Lake Yoa in northern Chad showed … ENN: Sahara dried out slowly, not abruptly: study