Abstract:

With rapid changes in climate and the seasonal amplitude of carbon dioxide (CO₂) in the Arctic, it is critical that we detect and quantify the underlying processes controlling the changing amplitude of CO₂ to better predict carbon cycle feedbacks in the Arctic climate system. We use satellite and airborne observations of atmospheric CO₂ with climatically forced CO₂ flux simulations to assess the detectability of Alaskan carbon cycle signals as future warming evolves. We find that current satellite remote sensing technologies can detect changing uptake accurately during the growing season but lack sufficient cold season coverage and near-surface sensitivity to constrain annual carbon balance changes at regional scale. Airborne strategies that target regular vertical profile measurements within continental interiors are more sensitive to regional flux deeper into the cold season but currently lack sufficient spatial coverage throughout the entire cold season. Thus, the current CO₂ observing network is unlikely to detect potentially large CO₂ sources associated with deep permafrost thaw and cold season respiration expected over the next 50 y. Although continuity of current observations is vital, strategies and technologies focused on cold season measurements (active remote sensing, aircraft, and tall towers) and systematic sampling of vertical profiles across continental interiors over the full annual cycle are required to detect the onset of carbon release from thawing permafrost.