近日，撒哈拉沙漠部分地区遇到罕见降雨，一些地方出现水从沙丘中冒出的奇景，有些干旱地区甚至遭遇暴雨引发的洪水。这是不是气候的极端变化？这并不是第一次气候影响撒哈拉沙漠了，大约12.5万年前的撒哈拉，还不是如今这片广袤的沙漠，而是一片草原林地。一切也都是因为气候变迁的问题。
Just pause for a moment and imagine the Sahara Desert.
You're probably picturing an arid landscape covered in sand dunes.
There's almost no water.
Out in the distance, there might be a few camels walking in the hot sun.
It's not the most hospitable place.
But ancient artists in northern Africa once saw a very different Sahara.
Like many artists, they painted what they saw around them.
And instead of what you just imagined, the scenery they re-created on rocks, starting at least 12,000 years ago, was dramatically different.
They made pictures of hippos and giraffes, and other savanna species that need to live near water.
There are even images of livestock and grazing animals, like cattle and sheep.
