Although air temperature at Toolik Lake is too variable for a warming trend to be statistically significant, several long term measures indicate warming. After 40 years, satellite data indicate “greening,” but plot re-harvesting in 2018 does not indicate an increase in shrub abundance. Alkalinity in Toolik Lake has doubled over 40 years, indicating deeper thaw, which allows water to flow through from deeper, more carbonate-rich soil layers. Stream water alkalinity, base cation concentrations, nitrate, and DOC have all increased in ways consistent with permafrost thaw. Dissolved phosphorus has decreased in the Kuparuk River, contrary to expectations.