Towards an observationally-constrained understanding of Northern high-latitude carbon cycle dynamics

One of the largest uncertainties in projected greenhouse gas concentrations and temperature trends is the impact from terrestrial and marine carbon-climate feedbacks, especially in the northern high latitudes (i.e., circumpolar Arctic and Boreal region North of approximately 50° latitude). While evidence is emerging about changes to various terrestrial and marine ecosystem processes, a comprehensive and integrated understanding of Arctic-Boreal carbon cycle dynamics and its interaction with the global carbon cycle remains elusive.

In this presentation, I will bring together results from an international group of scientists to show the power of atmospheric observations to diagnose Arctic-Boreal carbon fluxes, its current state (net source or net sink or approximately carbon neutral) and attribution to climate and disturbance drivers. With the projected increase in severity and frequency of disturbance events, such as wildfires and heatwaves, robust and accurate information about the current Arctic-Boreal state is critical to better predict its response to climate change. I will use this current understanding, along with findings from NASA’s decade-long ABoVE campaign and the international RECCAP-2 Permafrost effort, to illustrate the potential for atmospheric observations to provide unique insights into Arctic-Boreal carbon cycle dynamics. These observations not only provide a powerful tool for detecting change but also enable evaluation of process-based models, thereby informing and improving them. I will also show recent results from observing system simulation experiments that capture the observational capabilities we will ultimately need to better monitor changes and inform adaptation measures. The presentation will conclude with a discussion on the need for integrating this atmospheric information with other environmental datasets in order to obtain a truly integrated picture of the Arctic-Boreal system and identify its most sensitive parts, i.e., parts of the system in which carbon cycle responses will lead to substantial positive, or modifications of negative feedbacks, to the climate system.