Lichens are key components of high latitude and altitude ecosystems, contributing considerably to ecosystem functioning, carbon fluxes and total biomass. Pale lichens are also important food for reindeer, holding great ecological, economic, and cultural value. Despite the ecological, climatological and cultural importance of lichen however, there is today little knowledge about general trends in global lichen abundance, due to the previous lack of remote sensing methods. Here, using a novel remote sensing AI approach, we estimate lichen biomass trends over 35 years in 120 locations across the whole northern circumpolar region. We compare our results against existing literature and environmental datasets, investigating how lichen biomass changes differ between a) management regions, b) vegetation types, and c) drivers of vegetation change including effects of reindeer grazing and climate change.