Agulhas Current in southern hemisphere may stabilise or destabilise Europes climate

March 11th, 2009 - 3:38 pm ICT by ANI  

Washington, March 11 (ANI): New data has emerged that provides evidence in support of the hypothesis that the Agulhas Current, in the southern hemisphere, may stabilise or destabilise climate in Europe.

The data was presented by scientist Martinez-Mendez, in her PhD thesis titled Surface and Deep Circulation off South Africa: Agulhas Leakage Influence on the Meridional Overturning Circulation During the Last 345 kyr.

These new data profiles are not yet fully exploited and need to be implemented in global ocean models.

But, they do provide for the first time robust evidence in support of the hypothesis that the Agulhas water leakage into the Atlantic contributes to the strength of the Atlantic Ocean circulation at large, and the Gulf Stream in particular and therefore can stabilise or destabilise climate in Europe.

This knowledge will improve predictive capabilities which aim to project future climate developments in the North Atlantic region under global climate warming scenarios, such as those employed by the Intergovernmental Panel on Climate Change (IPCC).

The Agulhas Current transports warm waters from the tropical Indian Ocean to the southern tip of Africa.

It influences rainfall patterns and weather systems in southern Africa.

A part of the warm waters are transported around South Africa into the South Atlantic and influence the ocean circulation of the entire Atlantic Ocean.

Climate models predict that the amount of this water leakage from the Indian Ocean into the Atlantic may in fact strengthen or weaken the Gulf Stream in the North Atlantic with consequences for climate in Europe, including the Iberian Peninsula.

Measurements in the ocean so far have not permitted to test if a connection between the Agulhas Current around South Africa and the climate in Europe indeed exists.

For her project, Martinez-Mendez used stable isotope gas mass spectrometry and inductively coupled plasma mass spectrometry to analyze isotopic and chemical components in the sediments underneath the Agulhas Current, which document variations of this current in the past.

The data profiles document that systematic changes occurred in the Agulhas Current, which were directly connected with global climate changes.

The implications from this research are that the flow of water coming from the tropical Indian Ocean can occasionally form a warm water pool at the southern tip of Africa.

Under appropriate conditions, this water is abruptly released into the Atlantic Ocean.

Because these waters also have high concentrations of salt, they ultimately stimulate a density anomaly in the South Atlantic, which triggers internal waves in the deep water, and ultimately influence the Gulf Stream in the north. (ANI)

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