Hydro-climatic and lake change patterns in Arctic permafrost and non-permafrost areas

• Opposite change direction found generally in runoff from that in precipitation. • This contrast and lake changes are explained by evapotranspiration changes. • Basin-scale permafrost thaw is clearly indicated in only one lake-change area. This paper investigates patterns of lake-area and hydro-climatic change in Arctic river basins, and possible influence of permafrost change reflected in such patterns. A salient change pattern, emerging across all investigated basins in both permafrost and non-permafrost areas, is an opposite change direction in runoff ( R ) from that in precipitation ( P ). To explain this change contrast, an increase (decrease) in relative water-balance constrained evapotranspiration ET wb / P is required where R decreases (increases). Increasing temporal variability of daily river discharge ( sdQ ) is found in all basins with spatially extensive lake decrease, which also exhibit decrease in ET wb / P . Clear indication of basin-wide permafrost thaw is found in only one basin, and is possible in two more, but unlikely in the largest of the total four investigated permafrost basins.