Broecker, Wallace (1931-)

WALLACE BROECKER IS an American oceanographer, Newberry Professor of Geology at Columbia University, and scientist at the Lamont-Doherty Earth Observatory who made major contributions to chemical oceanography, especially oceanic mixing based on radioisotopic distribution. Broecker set the research agenda for the field of paleoclimatology, thanks to his ability to devise coherent pictures of how all the different elements of the Earth shape the planets climate. In particular, Broecker focused on the influence of oceans in triggering abrupt climate changes. His research has made him one of the most often-quoted scientists in contemporary debates about global warming. A New York Times reporter described him as the “iconoclastic guru of the climate debate.”

Broecker was born on November 29, 1931, in Chicago, Illinois, where his father ran a gas station. He grew up in a fundamentalist Christian family and attended Wheaton College, a fundamentalist institution, before transferring to Columbia University in 1952. Broecker soon rebelled against his religious fundamentalist background. The skepticism that informs much of his scientific interest in the exceptions to general rules may be the result of this rebellion against the stifling religiosity of his family.

Broecker stayed at Columbia for his entire academic career. He earned his doctorate in 1958 and, a year later, became assistant professor. In 1961, he became associate professor, and in 1964, he was appointed full professor. In 1977, Broecker was named the New-berry Professor of Geology and, two years later, he was elected to the National Academy of Sciences and named chair of the Geochemical Society.

Broecker is the author of more than 400 articles and seven books. He began his research in the 1950s, developing techniques to measure the radiocarbon content of ocean water. He used his data to trace ocean circulation patterns over time. His researches connecting climate change with radiocarbon dating of marine shells found in sediment deposits on the sea bottom helped to date the abrupt end of the most recent ice age, approximately 11,000 years ago.

In the 1970s, Broecker was among the leaders of the Geochemical Ocean Sections (GEOSECS) program, which gathered information from the world's oceans through radiocarbon dating. In the mid-1980s, Broecker devised his theory of global ocean circulation, which is often called Broecker's Conveyor Belt. He theorized the circulation of chemical elements in the sea, the thorough mixing of surface and deep waters of the ocean that takes place every 1,000–2,000 years, and the rate of gas exchange between the atmosphere and the ocean.

Broecker came to the conclusion that climate is extremely volatile. It can cool down, as well as warm up very quickly, and these alterations can produce global changes. The Earths climate is subjected to the on and off action (thus the conveyor metaphor) of deep ocean currents that transport great amounts of heat around the planet. Broecker used radiocarbon dating of samples of ocean water to study the world's oceans. He was one of the first scientists to stress the importance of the carbon cycle and to be able to work out its chemical processes. His research also pointed out the ocean's influence on atmospheric carbon dioxide levels.

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