Ocean circulation changes ‘more dramatic than previously thought’

January 15th, 2011 - 3:03 pm ICT by ANI  

Washington, Jan 15 (ANI): A new study from Cardiff University has revealed that ocean circulation changes this winter may have been more dramatic than previously thought.

The study found that as the last Ice Age came to an end the formation of deep water in the North-East Atlantic repeatedly switched on and off, causing the climate to warm and cool for centuries at a time.

Oceans help regulate global climate through the transport of heat carried by vast ocean currents, which together form the ‘Great ocean conveyor’.

The key to this conveyor is the sinking of water in the North-East Atlantic, a process that causes warm tropical waters to flow northwards in order to replace the sinking water.

“We retrieved ocean sediment cores from the seafloor of the Northeast Atlantic which contained the shells of small organisms. We used these shells to examine the past distribution of radiocarbon in the ocean,” said Dr David Thornalley, Cardiff School of Earth and Ocean Sciences.

“Radiocarbon is a radioactive form of carbon that acts like a natural stopwatch, timing how long it has been since water was last at the sea surface. This allows us to determine how quickly deep water was forming in the Northeast Atlantic at different times in the past.”

The team of scientists found that each time deep water formation switched off, the Northeast Atlantic filled up with water that had originally formed near Antarctica and then spread rapidly northwards.

The new results suggest that the Atlantic ocean is capable of radical changes in how it circulates on timescales as short as a few decades.

“These insights highlight just how dynamic and sensitive ocean circulation can be. Whilst the circulation of the modern ocean is probably much more stable than it was at the end of the last Ice Age, and therefore much less likely to undergo such dramatic changes, it is important that we keep developing our understanding of the climate system and how it responds when given a push,” concluded Thornalley.

The findings are published in the journal Science. (ANI)

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