Monday, July 2, 2012
Voyage into Ancient Climates
Researchers from the National Oceanography Centre in Southampton are setting off on a mission to drill the deep seabed of the north Atlantic for secrets about the climate during the planet's last lengthy spell of extreme warmth, which happened around 30 million years ago.
From the drillship JOIDES Resolution, the scientists will drill down into the seabed up to 5km below, recovering sediment cores that will shed light on long-ago climates. Analysing these cores will provide one of the world's longest and most undisturbed records of climate change, providing detailed information about ancient ocean circulation and weather patterns.
The mission focuses on the sediment around the Newfoundland Ridges, hundreds of kilometres off the Canadian coast. It will sample 11 sites, coring down as far as 400m into the mud to find sites where ancient climates were affected by CO2-fed global warming. The technique works because as atmospheric CO2 rises, the ocean becomes more acidic; this changes the types of sediment deposited on the sea floor.
The deep waters of the north Atlantic are forced to flow over the Newfoundland Ridges, and two major current systems - the north-flowing Gulf Stream and the south-flowing Deep Western Boundary Current cross over around the planned drilling area. The sediments they leave behind preserve a record of their flow strength and chemical composition, as well as of the living things in the water at the time.
The rate of sediment deposition also depends on the strength of the current passing over the seabed, so NOC scientists plan to use their findings to gain a detailed history of the Deep Western Boundary Current, which runs from the Greenland Sea down to the east coast of North America, and is thought to help drive the Gulf Stream, which in turn profoundly influences the European climate. So the results will help researchers understand the intricate relationship between ocean circulation and the climate.
The voyage is planned to last until early August.