We're putting unprecedented pressure on protected lands

Mangrove forest, which is an ecosystem at particular risk.
Mangroves on Cayo Coco in Cuba. Photo: Prisma by Dukas/UIG via Getty Images

Human activities are encroaching on the lands we've set aside to protect vulnerable species, according to new research.

Key findings: The study, published Thursday in Science, found that about 33% — or roughly 2.3 million square miles — of protected land worldwide is under "intense human pressure" from development, such as roads, growing urban areas, and agriculture. Only 42% of protected land is free of any "measurable human pressure," the researchers found.