The fate of climate change-induced methane formation in the sediment-ocean-atmosphere system

Methane (CH4) is a potent greenhouse gas.

The atmospheric CH4 concentration has tripled since pre-industrial times and is now increasing faster than ever in the observational record.

Our current inability to predict the trajectory of the atmospheric CH4 concentration indicates a formidable knowledge gap in global CH4 dynamics and its response to climate warming. About half of the global CH4 emissions come from aquatic sources.

While gas bubble emissions (ebullition) represent a large fraction of the total aquatic flux, the dynamic controls of seafloor ebullition remain poorly constrained.

The central question in this project is: will climate warming-induced CH4 formation in sediments lead to increased CH4 emissions to the atmosphere?

There are several factors suggesting it will but no studies to date have investigated the coupled transport of dissolved and gaseous CH4 through the sediment-water column, and the resulting emissions to the atmosphere. Here, this will be done by combining a numerical sediment model with a coupled ocean-bubble model.

This will allow us to shed light on where and when our oceans can become hotspots for CH4 emissions, and to make quantitative emission estimates.

The models will be validated through an observational program including surveys with RV Electra and two icebreaker expeditions to the Arctic Ocean with IB Oden; each icebreaker expedition is fully funded and contains components tailored towards the research goals presented here.