This chapter provides an overview of observed changes in vegetation productivity in Arctic tundra and boreal forest ecosystems over the past 3 decades, based on satellite remote sensing and other observational records, and relates these to climate variables and sea ice conditions. The emerging patterns and relationships are often complex but clearly reveal a contrast in the response of the tundra and boreal biomes to recent climate change, with the tundra showing increases and undisturbed boreal forests mostly reductions in productivity. The possible reasons for this divergence are discussed and the consequences of continued climate warming for the vegetation in the Arctic region assessed using ecosystem models, both at the biome-scale and at high spatial resolution focussing on plant functional types in the tundra and the tundra-forest ecotones.