JOIDES Resolution
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.
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