Less than one-quarter of the world's forests show no obvious signs of human activity, and the proportion of undisturbed forest has dropped markedly since the millennium.

Peter Potapov at the University of Maryland in College Park and his co-workers used satellite images to identify areas of intact forest larger than 500 square kilometres, and compared their sizes in 2000 and 2013. During that period, 7.2% of intact forest landscapes around the globe disappeared. In protected areas the proportion was lower, with a loss of only 1.8%.

Worldwide, logging was the leading cause of intact forest loss, followed by land-clearing for agriculture. Designating forest lands as protected helped to preserve pristine environments, although this was more effective in preventing logging than agriculture.

Sci. Adv. 3, e1600821 (2017)