Analysing a sediment record from Stóra Viðarvatn (NE Iceland), we reveal how natural factors and human activities influenced environmental changes (erosion, wildfires) over the last 11 000 years. We found increased fire activity around 3000 and 1500 years ago, predating human settlement, likely driven by natural factors like precipitation shifts. Declining summer temperatures increased erosion vulnerability, exacerbated by farming and animal husbandry, which in turn may have reduced wildfires.