In a warming climate, precipitation across the Arctic will increase and become more variable and extreme summer rainfall events are expected to occur more frequently. There is little experimental evidence of the impacts of such rainfall extremes on Arctic ecosystems. In the intended project we will investigate whether extreme rainfall can accelerate or slow down the thawing of permafrost, affect productivity and phenology of Arctic vegetation, affect food source quality and dynamics of herbivores and abundance and community composition of arthropods. We will also assess the role of landscape heterogeneity (locations in Adventdalen, Endalen and Ny-Alesund) and timing of heavy rainfall events (late summer vs. early summer treatment) in assessment of heavy rainfall impacts. We will use an established and controlled experimental setup in the field and expect to deliver high quality data on a multitude of aspects of ecosystem functioning under future increases in heavy rainfall on Svalbard.