Association between permafrost degradation and soil greenhouse gas fluxes in the Alaskan Arctic

The Arctic is projected to warm at nearly twice the rate of the global average in the coming century. Climate change can generate both negative and positive feedbacks with Arctic ecosystems: As atmospheric carbon dioxide increases, plants grow more quickly, thus absorbing more carbon. As temperatures rise however, Arctic permafrost thaw could make more soil carbon susceptible to microbial degradation, leading to the release of more greenhouse gases (positive feedback) or more nitrogen for plant growth (negative feedback). Therefore, to accurately predict the effects of climate change, we must understand how the amount of greenhouse gas flux from the soil surface changes with soil temperature, soil moisture, depth to frozen ground, microtopography and permafrost degradation. ` We conducted fieldwork in the Alaskan Arctic, at the Barrow Environmental Observatory as part of the U.S. DOE Next Generation Ecosystem Experiment (NGEE-Arctic). We sampled from areas that are representative of three levels of permafrost degradation: low-centered, transitional, and high-centered. Each sampling area may be further decomposed into three microtopographic components: troughs, edges, and centers. We measured the soil greenhouse gas fluxes and flux variability of each treatment over the growing season (using static chambers), soil moisture, soil temperature, and depth to frozen ground. As permafrost thaws during the growing season, we observe how greenhouse gas fluxes change as depth to permafrost increases. This may allow us to extrapolate how greenhouse gas fluxes would change due to a climate-change-induced temperature increase.