Alaska is at the forefront of experiencing the effects of climate change as it has warmed twice as fast as the contiguous US. Sea ice, glaciers and permafrost are melting, spring snowmelt is occurring earlier, river ice break-up is happening earlier; all of this affects local ecosystems and wildlife habitat and dries landscapes. Precipitation in Alaska is expected to increase with the greatest increases in western Alaska. With long-term increases in precipitation river flows and erosion will increase. Glacier and snowfield ice melt will increase summer river-flow as long as the glaciers and ice fields themselves remain large enough to contribute flowing water.
About 80% of Alaska is underlain by permafrost or frozen ground. Because permafrost contains surface water, an increase in temperatures that melt permafrost will lead to mobilization of subsurface water and rearrangement of surface water in ways not previously experienced. Hence melting permafrost will contribute to drier landscapes, more wildfires, loss of infrastructure, and changes in wildlife and wildlife habitat, and will release heat-trapping gases into the atmosphere. Climate projections show more areas without permafrost, which will increase winter stream flows, decrease summer peak flows, increase stream water temperature and change water chemistry. Over 70% of permafrost in Alaska is land vulnerable to sinking.
With climate change many shifts in ecosystems are expected in Alaska. With warmer temperatures there is an increase in the probability of new invasive species. Increased wildfire frequency is predicted, even in areas where fires have been largely absent. Already fires are occurring in arctic Alaska, which is novel. Coastal forests may also experience wildfires under future climates. As temperatures warm, boreal forests will move north in latitude and higher in elevation, and many species will shift their ranges.