Environmental Studies Professor Louisa Bradtmiller

St. Paul, Minn. – If you’re like a lot of Americans, swimming in the ocean is a favorite summer activity.  But did you know that ocean circulation can affect the Earth’s climate?

While many things likely contribute to modern climate change, scientists believe that ocean circulation has had a major impact on Earth’s climate over the past 20,000 years. Macalester Environmental Studies Professor Louisa Bradtmiller recently co-authored a paper in Paleoceanography that helps to determine differences in ocean circulation between the last ice age and today.

Why is this so important? Because, according to Bradtmiller, “While we know a lot about what causes ice ages and non-ice ages (like we’re in now), we still don’t know exactly how everything works,” she said.  “So, understanding how the ocean is involved in climate change on timescales of tens of thousands of years is part of solving that problem.”

The ocean affects many parts of the climate system because water is a very unique molecule. It holds onto heat better than lots of things (much better than land, for example), so it is relatively constant in temperature, at least compared to continents. It also dissolves things, like carbon, and because the deep ocean is fairly isolated from the rest of the world, once carbon gets down there it remains for a long time (~1000 years). So, in addition to being important for heat transfer, the ocean also affects atmospheric CO2 (by holding onto more or less carbon), which also affects climate.

Earlier this year, Bradtmiller established that the deep Pacific Ocean (below 2000 meters) likely stored more carbon during the last ice age than during the Holocene (the last 10,000 years of the Earth’s history — the time since the end of the last major ice age).

Macalester College, founded in 1874, is a national liberal arts college with a full-time enrollment of 1,958 students. Macalester is nationally recognized for its long-standing commitment to academic excellence, internationalism, multiculturalism and civic engagement.  Learn more at macalester.edu

June 2 2011

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