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What is MOCA? 

The MOCA project will enhance understanding of the present atmospheric effects of methane released from dissociation of gas hydrates in Arctic seabed sediments, and will also inform on the future potential impacts in a warming climate on decadal to centennial timescales. 

Methane hydrates (MH) in ocean seabed sediments are a potential source of methane (CH4) to the atmosphere, where CH4 has potential to act as a powerful greenhouse gas. Recent scientific results studies show diversity in the flux of CH4 that actually reaches the atmosphere. MH are potentially susceptible to ocean warming, which could trigger a positive feedback resulting in rapid climate warming. 

MOCA is funded by the Norwegian Research Council and will apply advanced measurements and modelling to quantify the amount and present atmospheric impact of CH4 originating from MH. Furthermore, the project will investigate potential future climate effects from destabilisation of MH deposits in a warming climate, and will focus on scenarios in 2050 and 2100. 

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Methane measurement instrument on Helmer Hanssen

NILU scientists Adam Durant and Ove Hermansen spent a week onboard the University of Trømso research vessel "RV Helmer Hanssen" as part of the MOCA project. The purpose of the trip was to install instrumentation for measuring methane in the atmosphere over the Arctic Ocean, in preparation for a summer campaign to determine if gas emissions from methane hydrates at the ocean floor are reaching the atmosphere.



Methane is stored in subsea permafrost and marine sediments, in the form of methane hydrates – an ice-like substance. If the temperature rises, methane gas may leak from these deposits and form bubbles that rise in plumes towards the surface.  Depending on the water depth, the bubbles may reach the ocean surface, or dissolve before the gas can enter the atmosphere.

Testing equipment

Together with representatives from partner CAGE - Centre for Arctic Gas Hydrate, Environment and Climate at UiT, Adam Durant and Ove Hermansen are spending the week aboard the research vessel RV Helmer Hanssen. They are going to install a Picarro cavity ring down spectrometer, and a flask sampling apparatus to collect gas samples for isotopic analysis.

– This week is all about installing and testing the equipment, explains Adam Durant and expedition leader Stefan Buenz from CAGE, – but come June we will begin a series of ship campaigns and intensive measurements. The instruments on board the ship will be used to capture atmospheric signals. These signals indicate if methane is present at levels above background at the ocean surface that could potentially be related to methane seeping from the ocean floor and up through the water column.

The measurements taken on the ship are collected as air samples from the sea surface directly above known methane bubble plumes emitted from the ocean floor. Air is drawn in through an intake on a high point on the ship and down to the instruments. Besides methane, measurements of carbon dioxide, carbon monoxide, ethane and different isotopes are made - the latter to identify isotopic signatures, which can show where the measured air mass originated.

– Data is transmitted continuously from the ship to NILU via satellite, says Durant. – We want to be able to follow the measurements from NILU as well. If everything goes to plan, we and our partners from CAGE will be ready to embark on the first MOCA ocean research cruise in June.







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