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Discovery of an active methane gas system beneath Arctic seabed

24 September 2008

Researchers have discovered a methane gas system beneath the seabed off the west coast of Svalbard in the Arctic that has probably been active since the end of the last ice age, about 15,000 years ago.

The methane, much of which is stored in the sediment beneath the seabed as methane hydrate, flows upwards to the seabed surface where it enters the water as plumes of bubbles.

Led by Professor Graham Westbrook from the University of Birmingham, the research team from Britain and Germany found a field of more than 250 plumes of gas bubbles escaping from seeps in the seabed, in water shallower than 400m.

This is the first discovery of such plumes in this part of the Arctic.

Working from research ship the RRS James Clark Ross, the team took cores of sediment from beneath the seabed.

RRS James Clark Ross

In deeper water they found gas hydrate in cores close to where bubble plumes rise from depressions (known as pockmarks) in the seabed. Methane hydrate is an ice-like crystalline solid in which methane gas is trapped in 'cages' of bonded water molecules. This stores methane at high concentrations. Increasing temperature or reducing pressure melts the hydrate and releases the methane.

Using seismic profiling equipment the team obtained data to show the presence of methane and hydrate beneath the seabed, and imaged rock structures through which the gas naturally flows to the seabed. Sonar systems provided high-resolution maps and images of the seabed that identify the seeps and vents where methane can escape.

Professor Westbrook said, "The discovery of this system is important as its presence provides evidence that methane, which is a greenhouse gas, has been released in this climatically sensitive region since the last ice age. With an analysis of the numbers and types of fossils found in the sediments and their isotopic chemistry to show how the climate changed in the past, this will help us establish when, how rapidly and how much methane was released in response to changes in water temperature and depth as the climate changed."

The scientists, who are from the National Oceanography Centre Southampton, the Universities of Birmingham and Royal Holloway London and IFM-Geomar in Germany, have also taken samples of the atmosphere and the water itself to measure the concentration of methane present.

Professor Westbrook added, "Our results may also provide the means to assess the potential effect that future climate warming will have on these gas hydrate systems beneath the Arctic seabed."

The expedition was funded by the Natural Environment Research Council (NERC) as part of an International Polar Year project investigating the dynamics of gas hydrates in polar marine environments.

Further information

Professor Graham Westbrook
University of Birmingham
Mob: 07976 403808

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Notes

1. The research team arrived back in the UK today (24 September 2008).

2. The RRS James Clark Ross is part of the Natural Environment Research Council's fleet of research ships. It is operated by the British Antarctic Survey, one of NERC's research centres.

Press release: 52/08