Introduction to the Alaska Carbon Cycle Invited Feature

摘要

Ongoing warming in northern high latitude ecosystems such as those in Alaska has the potential to release carbon to the atmosphere through (1) exposing and mobilizing the large quantity of organic carbon stored in upland soils and permafrost, wetlands, and surface waters, (2) emissions associated with potentially more frequent and severe fires, and (3) greater methane emissions. However, there are several possible mechanisms that could counter this carbon release including enhanced photosynthetic uptake of carbon dioxide (from longer and warmer growing seasons, increased soil nitrogen availability, rising atmospheric CO_2) and a switch from more flammable conifer forest to less flammable deciduous forest (feedbacks between ecosystem structure/function and fire regime). The issue of how and where Alaska carbon storage is likely to respond in a changing climate is important to carbon management efforts at the national scale, as Alaska contains one-fifth of the area of the continental United States and stores approximately one-half of the country's land ecosystem carbon. Information about the amount and fate of carbon from Alaska could have national policy implications by offsetting gains in or adding to carbon sequestration elsewhere. Also, knowledge of responses of carbon in Alaska may help inform expectations about responses of carbon from northern high latitude ecosystems in Canada and Eurasia.