Deserts cover what fraction of the world's surface?

Deserts cover approximately 1/5 of the world's surface. This estimation is based on the understanding that deserts, which are defined by their low precipitation levels, occupy vast areas across various continents. The classification of these areas as deserts takes into account both hot deserts, like the Sahara, and cold deserts, such as those found in polar regions.

This fraction reflects the significant presence and ecological importance of desert biomes worldwide. They host unique adaptations in flora and fauna that contribute to biodiversity, notwithstanding the harsh conditions. Understanding the extent of desert coverage helps in discussions about climate change, land use, and ecosystem management, particularly in the context of increasing desertification caused by human activities and a changing climate.