Methane in and above the polar oceans

Methane is a potent greenhouse gas, with a global warming potential ~85 times that of carbon dioxide on a 20-year timescale. Atmospheric methane concentrations are rising, but the global sources and sinks of methane are inadequately defined. Global ocean emissions remain highly uncertain: aerobic and anaerobic production mechanisms have been observed, as has direct seepage from the sea floor.

A recent study reported the first observations of methane seepage from shallow nearshore waters in Antarctica, but little is known about the atmospheric significance of such seeps. Mechanistic understanding and quantification of ocean methane sources is critically needed to accurately project future marine emissions and atmospheric methane levels as Earth's climate changes.

The student will:

Investigate existing ship-board methane observations from past Arctic/Antarctic campaigns plus from north-south Atlantic latitudinal transects. Study ambient methane concentrations as well as derive methane emission fluxes.

Establish the first polar-wide assessment of methane isotopic fingerprints using air samples provided by partner Arctic/Antarctic stations/ships.

We aim for participation in a measurement cruise, sampling from the UK to Antarctica - observations in Antarctica targeting oceanic seeps, plus broader spatial surveys around algal blooms; concurrent air sampling to enable isotopic fingerprinting of methane sources using established (delta 13C) and novel (delta D) techniques. The project does not rely on cruise participation, and this project aspect is not guaranteed.