Scientists study sea floor to understand global warming

New Zealand researchers are to try to find out whether deep ocean currents around the country slowed in the last ice age in an attempt to better understand global warming.

They say that knowing how much of the carbon dioxide from the atmosphere was concentrated at the bottom of the ocean as glaciers advanced and later as the Earth warmed, is considered crucial to that understanding.

A US research vessel, Roger Revelle, will collect seabed cores that scientists hope will show how much carbon dioxide was in the ocean along the east coast of New Zealand.

It is hoped that new cores of sediment from the seabed will build an accurate picture of what the deep was like during the ice age - which ended about 16,000 years ago - and in the period of warming which followed.

New Zealand scientists, including three from the National Institute of Water and Atmospheric Research, one from Auckland University and one from Geomarine Research, will work with US colleagues in the study, which is funded by the US National Science Foundation.

The researchers want to build a better picture of what happened during the ice age changes in circulation of water around the world's oceans.

"We're trying to find out how quickly the change occurred and how much carbon dioxide was there. Things that could help us better understand the current global warming," the science leader of the research voyage, Liz Sikes, of Rutgers University said.

She said New Zealand could provide a unique record because the ash from North Island volcanic eruptions was laid down over wide areas of the seabed, and could now be seen as stripes in the cores of sediment that acted as time markers.

"Using the ash layers, we can nail the age of the sediment more precisely than anywhere else in the world," Dr Sikes said.

The research ship has previously sailed on scientific voyages around New Zealand in 1997 and 2002.

There are a total of 24 scientists on board for the four-week voyage, which will take cores at six sites in both sub-Antarctic and subtropical waters.

- NZPA