The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation

The Arctic Carbon and Climate (ACCLIMATE) permafrost carbon (C) observatory uses field observations to measure C fluxes, C isotope ratios, and ecosystem C pools in a tundra ecosystem that is undergoing rapid and irreversible change due to regional warming. Permafrost temperature at the Eight Mile Lake research watershed in Interior Alaska has been monitored for several decades, starting before permafrost degradation began in the early 1990s. This moist acidic upland tundra site is located in the southern permafrost zone, where permafrost temperature near zero is especially sensitive to ongoing changes in climate. The impact of permafrost degradation on plants, microbes, and ecosystem C balance began to be documented in the early 2000s. This is a unique dataset that has tracked tundra ecosystem function as the degradation of permafrost unfolded and provides an important southern counterpoint to other established northern tundra research sites. Carbon measurements, along with other key ecosystem variables collected by this observatory, fill important and emerging knowledge gaps that are critical for a landscape understanding about the impact of permafrost C on climate.