Figure GT.4
Green Sahara. This 7,000- to 9,000-year-old giraffe petroglyph (rock engraving) is in the Sahara Desert in Niger, Africa, where today it is very dry. Giraffes require woodlands, so the petroglyph’s presence indicates that the climate was once much wetter. This petroglyph illustrates how temporal scale can provide a greater understanding of how environments change over long time spans.(© Frans Lemmens/Lithium/age fotostock)