The 2008 Benjamin Franklin Medal in Earth and Environmental Science is presented to Wallace S. Broecker, Ph.D.

The world's oceans play a major role in the climate of the Earth, and oceanographers have used a variety of tools to explore the pathways of ocean circulation. In the 1950s, Wallace S. Broecker pioneered the use of radiocarbon, or carbon-14, to document the patterns and rates of circulation within the oceans. The radiocarbon content of the dissolved carbon in oceanic water masses is a measure of the length of time the water has been isolated from the atmosphere. Broecker's early work established a global pattern of deep ocean currents, later described as the "Great Ocean Conveyor." The Ocean Conveyor is the central concept for modern research in paleoceanography and paleoclimatology, fields that document how the Ocean Conveyor changes spatially and temporally, both responding to and modulating external forces on the Earth's climate system. Carbon-14 is widely known for its use in dating geological and archeological specimens. Broecker's research has used this and other geochemical dating tools not only to assess the pattern of ocean circulation, but also to study the history of climate change as preserved in geological records of the past several hundred thousand years. These records, combined with insights from deep-sea sediment records of the history of the Ocean Conveyor, demonstrate the fundamental role of the ocean in climate on a variety of time scales, from a few years to a many millennia. The understanding of this role is essential for the understanding of future global change caused by both natural and anthropogenic factors, an issue that has become increasingly urgent for scientists and policy makers in the past few years.