News Climate A lush, green Arabian Desert may have once linked Africa and Asia Long-gone grasslands may have provided migration routes at times over the past 8 million years The Arabian Desert is today a vast and barren landscapes. But humid periods over the last 8 million years may have brought ephemeral rivers and grasslands to the region, a new study suggests. Achim Thomae/Moment/Getty Images Plus By Martin J. Kernan 31 seconds ago The Arabian Desert, today the largest expanse of windswept sand dunes on Earth, experienced recurring periods of humidity millions of years ago, researchers report April 9 in Nature. The study may explain how mammals at that time survived the trek across what is now a vast and barren landscape. The findings come from mineral formations deep inside caves beneath the Arabian Peninsula. These speleothems — stalagmites and stalactites, formed by dripping rainwater — provide evidence that the region underwent repeated humid periods stretching back nearly 8 million years. The scientists used uranium dating to precisely determine the ages of speleothem samples, offering one of the oldest climate records for the region. Sign up for our newsletter We summarize the week's science breakthroughs every Thursday.