A mechanistic understanding of Arctic River Methane Emissions

Constraining the global methane (CH4) budget is an urgent need to predict future climate. Rivers are an important source of CH4 to the atmosphere, with surprisingly high rates of emissions in northern regions.

The high emissions from Arctic rivers are driven by lateral inputs from surrounding land and are very sensitive to climate, but challenging to assess.

Given the severe impacts of ongoing climate change at high latitudes, CH4 emissions from Arctic rivers have a large potential to further increase, but we are unable to quantify and predict future emissions due to a lack of process-based models that represent river CH4 emissions.

The limitation arises from our poor understanding of river Arctic CH4 cycling, with a clear lack of mechanistic studies that are foundational to advancing process-based models.

ARIMETH aims to address this issue, by initially generating the mechanistic understanding of Arctic riverine CH4 cycling. Subsequently, the project will develop the modelling tools to predict current and future CH4 emissions.

To achieve this goal, the project will conduct a comprehensive approach, including a whole-stream warming experiment, high-resolution measurements with state-of-the-art CH4 sensors coupled with remote sensing data, pan-Arctic sampling campaigns to find the sources of CH4 using carbon radioisotopes, and developing deep-learning mechanistic models for river CH4 emissions.

The outcomes of ARIMETH will offer ground-breaking insights into river CH4 cycling, spanning from the river itself to the catchment, and to pan-Arctic scale.

Finally, ARIMETH will determine if CH4 emissions from Arctic freshwaters are underestimated when lateral fluxes to rivers and emissions are not accounted for.

This is critical to predict future trajectories of global warming, as well as discover unrecognised feedbacks between the terrestrial-aquatic-atmospheric compartments in the broad carbon cycle.