Climate changes in the northern and southern hemispheres are linked by a phenomenon by which the oceans react to changes on either side of the planet.
A research team from the Universitat Autonoma de Barcelona and the Cardiff University has shown for the first time that ocean circulation in the southern hemisphere has, in the past, adapted to sudden changes in the north.
The research published today in Science will enable more accurate forecasts to be made on how the oceans will react to climate change.
The scientists have observed that at several periods in history when the temperature has increased in the northern hemisphere, the southern hemisphere has entered a cooling period, which creates a decrease in the amount of deep water transported to the Atlantic Ocean from the south.
The opposite effect also took place: when the climate cooled in the North Atlantic, the southern hemisphere entered a warmer period, causing water to be transported northwards.
These mechanisms linking the two hemispheres had already been observed in computer climate simulations, but this is the first time they have been confirmed with detailed data obtained from scientific experiments using weather records from the past.
This is the first evidence showing that waters in the southern hemisphere play an active role in sudden climate changes.
Today's climate in Europe and North America is greatly influenced by the gulf stream. This ocean current carries warm water from the Gulf of Mexico northwards along the Florida coast, eastwards across the Atlantic and southwards along the west coast of Europe, bringing a mild climate.
The strength of the current is dependent on the salinity of the water travelling from the south.
If the salinity decreases, the current weakens. Scientists predict that global warming could cause part of the Greenland ice sheet to melt, giving rise to increased levels of freshwater in the Atlantic Ocean.
This could reduce the strength of the gulf stream, creating a cooler, dryer climate in Europe and North America.
However, according to the authors of this latest study, the Atlantic Ocean could already be adapting to the changes brought about by global warming in the same way as it adapted to climate changes in the past.
The waters in the southern hemisphere are less salty than those in the northern hemisphere, and this freshwater in the south sinks to the ocean floor and is transported to the rest of the Atlantic, reducing the salinity of the North Atlantic Ocean and strength of the gulf stream.
Nevertheless, the researchers have observed a decrease in the volume of freshwater sinking to the floor of the South Atlantic Ocean.
According to Rainer Zahn, "although we don't know where global warming will take us, this could be a sign that the oceans are already adapting to the changes".
Universitat Autonoma de Barcelona
Subscribe To TerraDaily Express
New Research Indicates A 'Troubled' Greenhouse Is Brewing
Eugene OR (SPX) Mar 24, 2005
Climates like those of the movie "Monsoon Wedding" may extend more widely into Africa, North America and South America, according to a University of Oregon geologist's analysis of an ancient greenhouse event.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|