R. Lawrence Edwards

University of Minnesota


Primary Section: 15, Geology
Secondary Section: 16, Geophysics
Membership Type: Member (elected 2011)

Research Interests

Larry Edwards is a geochemist with interests in climate history, climate change,and geochronology. Edwards is known for his role in the development of modern uranium- thorium (or 230Th) dating methods. He and colleagues were the first to apply sensitive mass spectrometric techniques to the measurement of rare isotopes of uranium and thorium in natural materials. This work led to large reductions in errors in age and sample-size requirements, improvements in the accuracy of ages, and a doubling of the range of time accessible to 230Th dating (now the last 700,000 years). Using these techniques, Edwards and other have and continue to re-write the timeline of the mostrecent chapter of earth history, which includes major shifts in climate, the last stage of human evolution, and historical cultural changes. In addition, Edwards and others are working toward a full calibration of the radiocarbon timescale, a goal since the original development of the radiocarbon dating method around 1950. Edwards studies cave deposits, which record historic and pre-historic climate. Along with his collaborators, he is working on piecing together hundreds of thousands of years of Asian Monsoon history from caves in China. Using innovative strategies, he relates his cave climate histories to those from ocean sediments and from ice cores, thereby establishing patterns of changing climate in time and space. His work helps us to understand the causes of abrupt climate change and the causes of the rapid melting of ice sheets at the end of glacial cycles. Some of his research assesses the relationship between climate change and cultural history, drawing plausible links between shifts in rainfall patterns and major cultural changes. His cave records that cover the last several centuries contain some of the strongest evidence yet for human-induced climate change.

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