Paleoclimate and archaeological evidence tells us that, 11,000-5,000 years ago, the Earth's slow orbital 'wobble' transformed today's Sahara desert to a land covered with vegetation and lakes.

For centuries, Earth’s oceans have always been blue. However, research states that oceans will turn green again soon. By again, I mean, once upon a time the oceans used to be green; now, they are blue ...