Arctic greenhouse gas sinks: exploring coldspots of methane and nitrous oxide in the permafrost domain

ongoing

The release of greenhouse gases from the terrestrial biosphere is of global importance. The Arctic is a net source of the greenhouse gases methane (CH4) and nitrous oxide (N2O), and a biogeochemically important ecosystem due to immense soil carbon and nitrogen pools and above-average warming. An observation-bias in Arctic greenhouse gas reporting towards high-emitting ‘hotspot’ sites is evident. In contrast, uptake of CH4 and N2O by Arctic soils, leading to greenhouse gas removal from the atmosphere, could partially compensate for carbon and nitrogen losses and completely redefine our baseline understanding of Arctic and global greenhouse gas budgets. No consideration has been given to understanding natural CH4 and N2O sinks in the Arctic, and the complex biogeochemical mechanisms governing these ‘coldspots’. I aim to show that Arctic greenhouse gas uptake matters, and that, contrary to traditional beliefs, intricate temporal uptake patterns exist and are driven by plant and microbial functioning. COLDSPOT will fulfil the scientific need to know when, where, and why Arctic soils act as a sink for CH4 and N2O, and will identify novel mechanisms underlying Arctic greenhouse gas uptake. High-resolution, laser-based measurements of soil CH4 and N2O uptake at field sites in Canada, Greenland, and Finland will be combined with machine learning tools and in-depth studies of environmental drivers in sophisticated experimental manipulations. COLDSPOT applies a multi-scale approach combining field-based measurements of multiple gas species with climate simulation experiments in state-of-the-art climate chambers in the laboratory, and investigations ranging from the microbial scale, via soil and plant processes to ecosystem-scale models. COLDSPOT will generate new process-understanding, fundamentally transform our perception of the magnitude and functioning of greenhouse gas sinks in the Arctic, and provide breakthrough insights for Arctic and global greenhouse gas research.