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Citation for Richard B. Alley: Horton Award 1996
Richard has played a central role in the ice core program, which is one of the most important programs in global science today. Through the extraction and analysis of ice cores, we are gaining more information about our environment, present and past, than we could possibly gain by any other means. That is why many of the results are published in Nature or Science and are widely followed in the press. Of course this knowledge does not come easily nor does it come without controversy. Thus it is essential to have people involved who understand the entire range of problems and can synthesize the complete picture. This takes a wide range of skills and a dedication to the job that is truly exceptional. In Richard's case he has spent a fair portion of his life doing field work on the big ice sheets, has detailed knowledge of the physical processes involved in all aspects of the ice sheets from snow metamorphism to ice creep, has detailed knowledge of the climatic history of the ice sheets and the impact of ice sheet work on the climatic history of the Earth, and has well developed skills in both numerical modeling and laboratory work. In addition to his contributions to the science directly, he has already directed a wide range of students and post doctoral colleagues in their work and is very active in teaching and in university committees. While at his age his contributions to professional societies have been modest, his contributions to the ice core, sea-level and climate communities have been exceptional. He is the first person to be asked to serve on NSF panels to direct future work in this area and he is constantly sought for reviews of proposals and manuscripts (about 60 per year) because of the huge effort he puts into these thankless tasks.
The importance of his work can best be judged by the citations and recognition that comes with making an impact. For example, his list of citations in the most recent edition of Paterson's classic text, Physics of Glaciers, exceeds any other author's, even all of the pioneers in the field. The Science Citation Index shows an average of about 150 citations per year to his first-authored work by other researchers in recent years, numbers that prove a high level of impact. More importantly, almost every paper he has ever written is cited every year. His recognition also includes the Packard Fellowship and the Presidential Young Investigator.
Although the scope of his indirect contributions would be impressive for someone twice his age, his direct contributions to the advance of the science are what really make Richard exceptional. He has contributed to our understanding of rapid climate change (the 1 to 3 year end of the Younger Dryas event) by generating the first long, annual-resolution record of snowfall. This is based on a major research effort involving remote sensing, surface studies, modeling and ice-core studies to show that ice cores display a seasonal oscillation controlled by the effects of summer sunlight, an unequivocal seasonal indicator, and that these physical differences can be identified accurately and repeatably in ice cores by a trained observer.
Combining these observations with knowledge of ice-flow corrections then allows reconstruction of the hydrological part of the climate over tens of thousands of years. He and his research team have developed a range of paleothermometers, and especially borehole-temperature calibration of the stable-isotopic thermometer, providing unprecedented confidence in climatic reconstructions and documenting changes twice as large as previously estimated (more than 200C warming since the glacial maximum in Greenland). They have used atmospheric modeling to demonstrate that previous Greenlandic paleothermometry was in error in part because of changes in seasonality of snowfall. By comparing accumulation-rate and temperature changes, they have documented that major climate changes were accompanied by major reorganizations of atmospheric circulation. Richard also has developed techniques to correct for the effects of accumulation-rate changes on ice-core chemical data, producing better estimates of paleo-atmospheric conditions. Richard and his team have thus greatly improved the dating of the ice cores, and the reconstruction of past temperatures, snow accumulation, and atmospheric-contaminant loading, opening new windows on climate change.
This research on climate change, ice physical properties, remote sensing and borehole paleothermometry would make a full career, but Richard is equally known for his contributions on ice-sheet dynamics and sea-level change. His role in demonstrating a soft glacier bed under West Antarctic ice streams helped touch off a massive reappraisal of ice-sheet stability that is affecting numerous fields, ranging from prediction of West Antarctic instability to interpretation of Heinrich-event sedimentation in the North Atlantic. Glacial geologists and glaciomarine sedimentologists are testing and confirming his insights on glacial debris transport. His work on glacial hydrology linked to ice flow and sedimentation provides a necessary bridge between the complex field data and the relative simplicity required by computer modelers. Richard has been unique in his ability to move from rapid climate change to glaciomarine sedimentation to remote sensing of ice sheets, and to serve as a preferred representative in planning meetings for both the ice-core-paleoclimatology community and the ice-dynamics/sea-level-rise community.
Although Richard has only had a faculty appointment since 1988, his research contributions and impact already exceed what most of us could hope to achieve in a career. Accordingly, the Section of Hydrology recognizes his accomplishments by giving him the Horton Award.
Samuel C. Colbeck
CRREL