Our first horizon scan, conducted in 2009, aimed to identify novel but poorly known issues with potentially significant effects on global conservation of biological diversity. Following completion of the tenth annual scan, we reviewed the 15 topics identified a decade ago and assessed their development in the scientific literature and news media. Five topics, including microplastic pollution, synthetic meat, and environmental applications of mobile-sensing technology, appeared to have had widespread salience and effects. The effects of six topics were moderate, three have not emerged, and the effects of one topic were low. The awareness of, and involvement in, these issues by 12 conservation organisations has increased for most issues since 2009.