Sunlight has more powerful influence on ocean circulation and climate than North American ice sheets
9 11 2008
From Physorg.com: A study reported in today’s issue of Nature disputes a longstanding picture of how ice sheets influence ocean circulation during glacial periods.
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, according to the article. The new study goes back 425,000 years, according to Lorraine Lisiecki, first author and assistant professor in the Department of Earth Science at the University of California, Santa Barbara.
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. Read the rest of this entry »