Summer differences among Arctic ecosystems in regional climate forcing

Biome differences in surface energy balance strongly affect climate. Howeve r, arctic vegetation is considered sufficiently uniform that only a single arctic land surface type is generally used in climate models. Field measure ments in northern Alaska show large differences among arctic ecosystem type s in summer energy absorption and partitioning. Simulations with the Arctic Regional Climate System Model demonstrate that these variations in land su rface parameters and ecological processes cause variation in surface fluxes that is sufficiently large to affect the regional climate. Plausible chang es in arctic vegetation in response to high-latitude warming would feed bac k positively to local summer warming. This local warming could extend into the boreal zone. Climate feedbacks that operate during the growing season a re particularly likely to impact vegetation and ecosystem properties. These field and model results suggest that vegetation changes within a biome cou ld be climatically important and warrant consideration in regional climate modeling.