Nearly half of the world’s land surface is now classified as drylands and these areas are accelerating their own proliferation, according to new research.

The findings, published August 29 in the journal Science, show around 45% of global land surface comprises deserts, shrublands, grasslands, and savanna woodlands. A chief characteristic of these regions is water scarcity, which significantly affects natural ecosystems and human-managed landscapes, including agriculture, forestry and livestock production.

While it has long been known that climate change and land management practices contribute to dryland expansion, the results revealed a surprising factor: drylands themselves are accelerating their own spread.