To date, humans have transformed more than three-quarters of the Earth. At least 1 million species are at risk of going extinct. At least 21% of the net global greenhouse gas emissions are associated with land-use change. We need to safeguard nature’s last remaining strongholds—the most important and intact wild landscapes and seascapes, which provide habitat for half the biodiversity on our planet, host the world’s largest wildlife aggregations, and are essential to our own well-being.