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Scientists gather valuable information on gas hydrates - 09/02/2007

Scientists on the German research ship Sonne have completed the first part of a three-month investigation of gas hydrates under the seafloor off the North Island's East Coast.

Crew on boat

They have successfully used a range of sophisticated instruments to probe deposits of frozen methane beneath the seafloor. The frozen methane is a potential source of natural gas fuel. Scientists are also concerned that these deposits can vaporise under natural conditions and possibly contribute to global warming.

Gas hydrates, or methane hydrates, are a solid ice-like form of water that contains methane gas molecules in tiny cavities. They occur naturally under the seafloor, usually in the top 500m of sediment.

Extensive deposits between Cook Strait and East Cape have led some scientists to describe the region as being "paved in gas hydrates".

The ship called in to Wellington last week for a brief stop-over to take on fresh supplies and extra scientific equipment.

In the first leg of the voyage, the scientists used acoustic equipment to get an insight into the sediment layering in the top 100m beneath the seafloor. They also measured the amount of methane at the sea surface to study the link between gas hydrates and rising methane concentrations in the atmosphere.

The first leg of the voyage studied four areas in detail with a deep towed side-scan sonar system to get high-resolution maps of areas where methane is seeping naturally into the ocean.

The voyage included the first-ever marine electromagnetic measurements in the New Zealand region.
Preliminary analysis of this information shows high concentrations of gas hydrates offshore from Cape Palliser in south Wairarapa.

Methane is a powerful greenhouse gas which - volume for volume - is 21 times more effective than carbon dioxide at trapping the sun's heat.

There is debate among scientists whether a major warming of the Earth 55 million years ago may have been caused by the rapid release into the atmosphere of huge volumes of methane from gas hydrates.

The scientists want to find out how quickly the chemical and physical changes take place that lead to instability of the gas hydrates.

It is already accepted that there will be times when large amounts of methane are released, but it is still not known if periodic bursts can cause dramatic changes to the Earth's climate.

The research has been taking place on the 98m-long Sonne and it is funded mainly by Germany's Research Centre for Marine Geosciences (IFM-GEOMAR). It involves 25 scientists from four countries. New Zealand organisations participating are GNS Science, NIWA, and Otago University.

The voyage will continue until the end of March and is taking place off the Wairarapa and Hawke's Bay coasts. The project is seen as the start of an extensive programme in New Zealand to find out more about the distribution of gas hydrates and the natural processes that control them. The Sonne finishes the second of three legs in Napier on February 25.