Sunlight has more powerful influence on ocean circulation and climate than ice sheets

November 7th, 2008 - 4:16 pm ICT by ANI  

Washington, Nov 7 (ANI): A new study has suggested that the distribution of sunlight, rather than the size of North American ice sheets, is the key variable in changes in the North Atlantic deep-water formation during the last four glacial cycles.

The study, by Lorraine Lisiecki, assistant professor in the Department of Earth Science at the University of California, Santa Barbara, and her team, goes back 425,000 years.

Lisiecki and her co-authors studied 24 separate locations in the Atlantic by analyzing information from ocean sediment cores.

By observing the properties of the shells of tiny marine organisms, called foraminifera, found in these cores, they were able to deduce information about the North Atlantic deep water formation.

Scientists can discern historical ocean temperature and circulation patterns through the analysis of the chemical composition of these marine animals.

Previously, scientists relied on a study called Specmap, performed in 1992, to find out how different parts of the climate system interacted with one another during glacial cycles.

Specmap analyzed ocean circulation at only one place in the Atlantic.

What I found was that the one site that the Specmap study used actually didn”t match most of the other sites in the Atlantic, said Lisiecki.

Lisiecki explained that the new data changes our understanding about how the different parts of the climate system are interacting with one another and in particular the influence of the ice sheets on climate.

Because the ice sheets are so large, it was a nice simple story to say that they were having the predominant influence on all the parts of the climate system, said Lisiecki.

But our study showed that this wasnt the only important part of the changes in climate. The distribution of sunlight is the controlling factor for North Atlantic deep water formation, she added.

According to Lisiecki, Our study tells us a lot about how the ocean circulation is affected by changes in climate.

The ocean does not always follow the climate; it exerts its own impact on climate processes. In other words, the ocean circulation doesnt just follow along with the rest of the climate, it actually changes in different ways than the ice sheets during glacial cycles, she added. (ANI)

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