Prof. Price  supervised Robert Rohde, a Physics graduate student at Berkeley. He designed and built the Berkeley Fluorescence Spectrometer that they used in a dark room at -25°C at National Ice Core Laboratory to measure fluorescence radiation emitted from ice cores. They measured tryptophan (Trp, an amino acid present in all microbes), chlorophyll (Chl, present in cells that extract energy from sunlight and produce oxygen that gives rise to aerobic organisms), and volcanic ash over 2300 meters of glacial ice from the 3400 m deep borehole at the West Antarctic Ice Sheet Divide. Among their findings, they discovered that chlorophyll and tryptophan decreased a factor ~3 in ice from 7 locations in Antarctica and Greenland and had up to 25% higher intensity in local summer than in local winter. With assistance from minority undergraduate students, they melted portions of ice cores under sterile conditions and discovered that the Chl and Trp in ice is due mostly to submicron-size bacteria with higher concentration in local summer than winter. In addition to epifluorescence microscopy, they used a technique called flow cytometry to measure fluorescence intensity of Chl and phycoerythrin, which emit in red and orange regions of the spectrum, respectively. They also showed that a substantial fraction of the cells were still alive, despite having been frozen into ice for up to 100,000 years. The higher concentration in summer suggested that many of the cells had been transported by winds from temperate latitudes onto polar ice. Price proposed that, using the most sensitive genomics techniques, one should be able to study evolution of cells in ice over hundreds of thousands of years by regarding their genomes in ice as frozen proxies of their genomes in warm oceans at times in the past corresponding to the ages of the ice as a function of depth. This idea has attracted several well-known microbial geneticists, who have agreed to collaborate in studying microbial evolution over as much as 700,000 years in the past by analyzing the genomes of microbes as a function of depth. For picocyanobacteria, with a generation time of ~1 day in warm oceans, this might provide information on microbial evolution over as much as 300 million generations. The role of storage in ice at temperatures as low as -50°C is to eliminate reproduction and greatly slow down mutations.

Using the laser-powered logging tool that Bay invented, he measured with millimeter depth resolution the climatic variations of dust concentration in ice cores at WAIS Divide down to the bottom at 3400 m (68,000 years), and he discovered hundreds of thin layers of volcanic ash that serve as time markers, many of which can be matched with layers at South Pole and Dome C in Antarctica and even occasionally in Greenland Summit. One of his research goals is to explore an apparent causal relationship between some eruptions and millenial climate change.

Bay developed a fully automated synchronization technique for large ice core datasets to reduce subjectivity and analysis time, based on techniques from speech recognition. Bay synthesized South Pole laser logging measurements with ice core and logging data from Dome C to reconstruct a South Pole record of impurity concentration, precision chronology, accumulation history, local spatial variability, several widespread volcanic ash depositions useful for dating, and surface roughness as a proxy for cyclonic activity.

Bay installed newly developed microtiltmeters in 48 optical modules at depths from 1800 to 2450 m in 36 IceCube boreholes at South Pole, which provides information on ice shear as a function of time and depth at temperatures of order -18 to -35°C. Over several years we expect to be able to measure the very weak shear strain in...

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