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French, NZ researchers hunt seabed climate clues

MEDIA RELEASE 25 January 2006

French and New Zealand researchers hunt for climate clues and giant avalanches on the seafloor

A major collaborative effort involving French and New Zealand researchers will be delving in mud beneath the seafloor this month, looking for clues about past and future climate change and its various effects on the seafloor.

The international research team – led by scientists from France’s University of Nice-Géosciences Azur and CNRS-Géosciences Rennes, and New Zealand’s National Institute of Water and Atmospheric Research (NIWA) -– will take advantage of the special capabilities of French oceanographic research vessel Marion Dufresne. The ship is one of the world’s largest research vessels and will be visiting New Zealand waters this month, calling in to Wellington on 30 January.

The marine sediments around New Zealand’s coastline hold an important record of past climate history that can be a key to answering some fundamental questions. Understanding the effects of past climate change will enable scientists to predict future changes, and potential phenomena such as catastrophic submarine avalanches.

Lying at the critical junction between northern-tropical climate influences and those of the Southern Ocean, the New Zealand region is internationally recognised as an ideal location to investigate ‘abrupt’ climate change (which in this context, means changes that occur over hundreds, rather than millions, of years). New Zealand’s sediments are like a tape recorder of past environments. Records of past climatic and oceanic conditions are held in the shells of microscopic animals, called foraminifera, found within the sediments, as well as in the grain size and mineral content of the sediments themselves. These records are key to our understanding of complex climate interactions between the atmosphere, oceans, and land, going back many thousands of years.

New Zealand’s continental slope along the east coast of the North Island is also known internationally for the occurrence of some of the world’s largest submarine avalanches, which involve slides of mountain-size blocks of rocks and mud. The largest of these, off East Cape, re-mobilised more than 2000 cubic kilometres of material – more material than even the biggest Taupo eruption - and the largest block, the size of the Mount Cook Massif, traveled more than 50 km along the seafloor from its origin less than 50 km from the coast. One huge slide of mud, with a volume of approximately 600 cubic kilometres, traveled more than 150 km north of East Cape. Submarine avalanches can be caused by various destabilising factors, including earthquakes and abrupt climate change, and can set off potentially catastrophic tsunamis. From clues in the seafloor, the researchers will be able to work out the timing and cause of past avalanches, with a view to predicting possible future events.

Marion Dufresne is the only ship in the world capable of taking intact cores of soft sediment long enough to give an accurate picture of past climatic and oceanic conditions. On 22 January, the research team will start a voyage that will take them from Hobart to the west coast of the South Island and up the east coast of the North Island, recovering 30-50 m long cores of sediment from the seafloor as they go.

The project forms the first part of a five-year major multi-disciplinary collaborative programme involving scientists from more than a dozen institutions in New Zealand, France, Australia, Germany and the U.S.

In addition, about ten New Zealand students will be participating in the research voyage onboard Marion Dufresne, and will assist scientists with their studies investigating environmental change, thus gaining invaluable experience from an international team of expert researchers.

ENDS

Notes for editors:

1. Marion Dufresne left Hobart on Tuesday 24 January and will call in briefly at Wellington’s Queens Wharf on Monday 30 January before carrying on to Auckland, where it is due to arrive on Monday 6 February. The ship is expected to arrive in Wellington between 0900 and 1100 hrs on Monday 30th. NIWA is setting up public information boards outside the ship.

2. Marion Dufresne was commissioned in 1995 to carry out global oceanographic research and to re-supply the French austral islands Crozet, Kerguelen, Amsterdam and Saint-Paul. It is one of the world’s largest scientific vessels, measuring 120 m in length and with a dead weight of 4 900 t. It carries a wide range of advanced oceanographic, geophysical and geological equipment. Among its arsenal of research tools are two that place this vessel at the forefront of global marine research: its giant piston corer ‘Calypso,’ capable of recovering deep-sea sediment cores 60 m long and weighing up to 10 t; and its multi-beam sonar mapper, which produces high-resolution images of the seafloor. For more information (in English) on Marion Dufresne: http://www.univ-brest.fr/IUEM/Universite_flottante/md.html. For information in French: http://www.ifremer.fr/ifrtp/pages/md.html.

3. The ship is named after French explorer Marc Joseph Marion du Fresne (1724-1772), who explored the Pacific and Indian Oceans, discovering Marion Island, Prince Edward Island and the Crozets, before exploring Tasmania and New Zealand. For a biography of Marion du Fresne, see: http://www.dnzb.govt.nz/dnzb/default.asp?Find_Quick.asp?PersonEssay=1M13.

4. The giant corer Calypso can be fitted with a sampling tube up to 75 m in length. The tube is slowly lowered to the seafloor on four cables and is attached to a heavy lead weight and a counterweight. Once the counterweight hits the seafloor, the corer piston is triggered and the tube is released down through the sediment to take the sample. Once the sample is taken, it is slowly extracted. For details of the coring process, see: http://www.univ-brest.fr/IUEM/Universite_flottante/calypso.html

5. The sediment cores will be analysed in various laboratories around New Zealand and overseas to determine their age and to work out past climate histories. The magnetic properties of the sediments will be used to characterise environmental changes, based on known changes in the earth’s polarity. Analysis of the ratios of various oxygen and carbon isotopes in the shells of foraminifera will yield information on past sea temperatures, currents, and weather conditions; while the particular mix of foraminiferan species present will tell us about the ocean environment (including temperature and salinity), based on their particular habitat preferences. The grain size and type of minerals making up the sediments will provide clues about their origins; for instance, whether they were washed down from the Southern Alps during periods of erosion, which could indicate high rainfall or movements of glaciers.

6. The New Zealand consortium is led by NIWA, with partners from GNS Science, the Universities of Otago and Waikato (financial partners), Geomarine Research (Auckland) and the Universities of Victoria and Canterbury.

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