2005
Penrose Medal

Minze Stuiver
University of Washington

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Presented to Minze Stuiver

 Citation by Donald J. Easterbrook

Minze Stuiver was born in Vlagtwedde, Groningen, The Netherlands. He received his M.S. degree in experimental nuclear physics and mathematics from the University of Groningen in 1953 and his Ph.D. in biophysics from the University of Groningen in 1958. The direction of Minze’s career was strongly influenced by his association with Hessel de Vries, professor of physics at the University of Groningen. De Vries started him on the way of developing and applying state-of-the-art physical measurement techniques to biological and environmental processes through rigorous mathematical analysis.

In 1959, Minze went to Yale University as research associate and postdoctoral research fellow at the Geochonometric Laboratory, where he developed the Yale ¹⁴C laboratory. In 1962, he became senior research associate and director of the Yale Radiocarbon Laboratory.

In 1969, he moved to the newly founded Quaternary Research Center at the University of Washington where he built the Quaternary Isotope Laboratory and was its director until his retirement in 1998. Minze’s proportional CO₂ counters, placed in a specially constructed underground laboratory, made Seattle the world leader in precision and range of radiocarbon dating. Reviving the pioneering work on thermal diffusion isotopic enrichment of ¹⁴C, initiated by De Vries in the 1950s, Minze set the world record for the oldest ¹⁴C measurement and contributed to our knowledge of the timing of early glacial climate variability. Pushing his K-Ar system to younger ages, he was able to overlap the ranges of these two methods.

His early work involved short-term variations in atmospheric radiocarbon and their relationship to changes in the solar magnetic field was groundbreaking and his measurements were state of the art. His research on solar activity through study of ¹⁴C in tree rings has had a major impact on solar and atmospheric research. Careful analysis of the atmospheric ¹⁴C fluctuations, revealed by the high-precision ¹⁴C calibration record, allowed Minze to demonstrate the role of the sun in modulating the production of ¹⁴C (Maunder, Sporer, and Wolf sunspot minimum). He also translated the atmospheric ¹⁴C calibration curve to oceanic reservoirs. The atmospheric ¹⁴C calibration provided via its modeled production modulation is an indication of solar activity over the past 12,000 years.

He also used radiocarbon to trace the pattern and timing of deep-ocean circulation. His highly precise measurements of the ¹⁴C to C ratio in inorganic carbon in sea water greatly advanced understanding of the rates of ventilation of the deep sea and established the role of mixing in the southern oceans as an important aspect in the “aging” of seawater. The gradual change in ¹⁴C concentration in deep waters, going from the North Atlantic to the Antarctic circumpolar current and from there into the Indian and the Pacific oceans provided an early demonstration and quantification of the deep part of oceanic circulation.

Minze was a key player in the all-important GISP2 ice coring project in Greenland. He produced the basic oxygen isotope measurements that served to define the abrupt Greenland climatic changes. He was the first to recognize the problem of seasonality in this record and he also made fundamental investigations of the role of the sun in the Holocene changes recorded in the Greenland core.

An important part of his research involved meticulous, high-precision dating of ancient tree rings that allowed calibration of radiocarbon ages to calendar ages that led to the widely used computer program (CALIB) for calibration of radiocarbon dates. Minze demonstrated the importance of solar influences on terrestrial production rates of radiocarbon in calibrating radiocarbon ages and gave an early indication of significantly higher atmospheric ¹⁴C levels during the glacial to interglacial transitions. His 1993 radiocarbon calibration paper is the most-cited geoscience paper of the 1990s, and he has been named the most-cited geoscience author in the past decade.

To expand his paleoclimatic research into ice core analysis, Minze obtained a high-quality mass spectrometer system for ¹⁸O/¹⁶O analysis. He and P.M. Grootes produced ¹⁸O records for the tropical Quelccaya ice core in Peru with Lonnie Thompson, the J-9 core and the Taylor Dome core in Antarctica, and the historic GISP2 core in Greenland. These records contributed to our understanding of the climate signal in tropical glaciers and North-South climate connections. The GISP2 ¹⁸O record provided one of the fundamental climate indicators and confirmed and quantified the many, extremely rapid, large, climate changes, first seen in the Younger Dryas/Preboreal transition and then found elsewhere in the last glaciation.

The significance of the new technique of mass spectrometric measurement of ¹⁴C using nuclear accelerators (AMS) was recognized by Minze early on. He and Grootes developed AMS at the University of Washington with applications to the direct dating of pollen, ¹⁴C in tree rings, corals, and atmospheric methane. By adding stable isotope mass spectrometry of carbon (¹³C/¹²C) and oxygen (¹⁸O/¹⁶O), he developed the tools to quantify changes in the hydrological and in the carbon cycle, related to climatic changes in the past. Mass spectrometry of ¹³C/¹²C, needed for the ¹³C fractionation correction of ¹⁴C concentrations was developed into an independent tool to quantify the anthropogenic input of CO₂ into the atmosphere (Suess-effect). In a study spanning the Pacific Coast from Chile to Alaska, Minze was able to quantify the man-induced change in atmospheric ¹³C concentrations over time and thus helped quantify the history of the greenhouse gas, CO₂. His critical analysis also showed the pitfalls, awaiting those who want to use tree rings for this type of study, by identifying strong influences such as the juvenile effect, canopy, exposure, and growth rate on the ¹³C isotopic composition. Together with his student Bob Burk, he demonstrated the use of oxygen in cellulose as a paleoclimatic indicator, dependent on latitude, temperature and relative humidity.

Over the past 40 years, Minze Stuiver has published 195 papers in radiocarbon geochronology, calibration of radiocarbon and calendar ages, use of radiocarbon as a tracer to assess the pattern and timing of deep-ocean circulation, and studies of polar ice cores. His work was previously honored by the 1983 Humboldt Award from Germany, the 1994 Pomerance Award of the Archaeological Institute of America, and the 2000 AMQUA Distinguished Career award in Quaternary Science. He has produced a body of work unrivaled in the field of geochronology and unequaled in its interdisciplinary applicability.

  2005 Penrose Medal - Response by Minze Stuiver

The Penrose award is very much appreciated. Being in the United States for the past 46 years has been a great experience for myself as well as spouse Anneke, and I thank GSA and all our friends very much for the nomination and citation.

With only a two-day head start on the Great Depression my entry in this world was not very auspicious. And to add insult to injury my high school years in Almelo, the Netherlands, were drastically influenced by a German occupation that lasted 5 years. The school became “home” to a couple of hundred soldiers and I remember classes, if they were given at all, in the public library, a bathhouse, and a textile factory. The teachers also had to compete with the harsh sounds of airplanes, sirens, occasional bombs and German propaganda on loudspeakers. My hat off to those teachers because it is utterly amazing that so many of their students did well in our present society.

My parents were Friesians, and Friesian was spoken at home. The Friesian language is much older than Dutch and is more related to English. During the war I spent many summers with relatives in Friesland because only in that province was sufficient food for a hungry teenager. An important Friesian in U.S. history is Peter Stuyvesant, the last governor of New Amsterdam. A good description of his ancestry is given by Russell Shorto in his “The Island at the Center of the World”. W.F.Duisenberg, the “father of the Euro”, and Mata Hari, whose name became a synonym for female spy, also were Friesians.

Post-war university life in the city of Groningen was peaceful. One of the students in our physics department was Abel Tasman, a descendant of the European “discoverer” of New Zealand. And, although I did not realize it at that time, there was a hint of Dutch–American ties. Maarten Schmidt, now a well-known astronomer at Mt Wilson and Palomar Observatories, was a co-student in my astronomy class. And Dutchman Vening Meinesz, known for his gravity measurements in submarines, was a recipient of the Penrose award in the nineteen forties.

The trouble with old age is that there is too much past to describe. Fortunately, there is radiocarbon dating as a tool for deciphering the past. The methodology is nearly sixty years old and has undergone substantial improvements during those years. Sample size has been reduced from tens of grams to milligrams and precision has improved from centuries to decades. Only marginal improvement has been made in the maximum age range due to modern ¹⁴C contamination in samples and equipment lines. The ¹⁴C isotope, after all, disappears from the scene with a half life of 5730 years and for the maximum age of about 60,000 radiocarbon years less than 0.1 percent of the original ¹⁴C is left to measure.

Samples of known age are needed for the conversion of radiocarbon ages to calendar year ages. Even though precision has improved over time, the best precision is still achieved using fairly large (~10 g C) samples of tree-ring dated wood (up to 12,000 years old) in gas counters. The combined measurements of several laboratories generate an internationally accepted calibration curve that converts a radiocarbon age to a cal (calibrated) age range. With high precision dating the cal age range can be limited in many cases to one or two decades. For instance, a major earthquake in the Seattle region was radiocarbon dated as between AD 1695 and AD 1710. Japanese historical tsunami data ultimately provided an AD 1700 historical year (Brian Atwater, this meeting).

Isotopes play important roles in the Earth sciences. My own work was on ¹³C, ¹⁴C and ¹⁸O. ¹⁴C, of course, is not solely used for the determination of time. There are many other applications, ranging from abyssal ocean depths to surface conditions of the Sun. Because the ¹⁴C production in the upper atmosphere is modulated by the solar wind variations in atmospheric ¹⁴C content occur that can be measured in tree-rings. The changes in tree-ring ¹⁴C yield a history of cosmic ray flux modulation by the Sun. Such a record is important for estimating past solar induced climatic change. Other applications focus on global ocean circulation (deep-water residence times), carbon transfer between atmosphere, biosphere and oceans (using 20th century nuclear bomb ¹⁴C and fossil fuel (¹⁴C free) carbon dioxide signals) and global deforestation rates.

Condensation temperature determines the ¹⁸O /¹⁶O ratio of precipitation. In ice cores this ratio mirrors climate change over long time intervals. Ice is not the only medium for this type of research, calcium carbonate in lakes (marl) and oceans (deep sea sediment and corals) as well as tree-ring cellulose can be used.

Large programs like GEOSECS with its worldwide ocean sampling, Taylor Dome and GISP-2 with kilometer long ice cores, and CALIB with thousands of tree-ring samples are now part of history, but not entirely forgotten. The lasting legacies are the data sets and the widely used CALIB calibration program. There also have been many interactions with colleagues and students during my career (AD1950 – 2000, give or take a couple of years) and these exchanges contributed substantially to the Penrose award. Unfortunately, a listing of all names would blow GSA editorial policy to pieces and a partial listing is dangerous territory (so I am told). Nevertheless, I like to acknowledge as mentors Hl de Vries, E. S. Deevey and A. L. Washburn, and as superb students Paula Reimer, T. Braziunas, R.L.Burk and E. Steig. And citationist Don Easterbrook, with much optimism, made this event a reality.