May 19, 2017
Former DoGS postdoc Jeremy Bassis, now an associate professor at Michigan, and PhD alumnus Mac Cathles, now an assistant professor at Michigan, have published a paper in Nature arguing that Heinrich events were triggered by ocean warming. Heinrich events are large discharges of icebergs from the ice sheet on North America during the last glacial period. The mystery is that they are associated with cold atmospheric periods. Bassis and Cathles have shown that they probably were associated with warm oceans near the ice sheet margins, and that the warm water temperature led to the calving of large numbers of icebergs. Both Bassis and Cathles were advised by Doug MacAyeal while they were in Chicago.
May 12, 2017
University of Chicago graduate students Kara Lamb and Ben Clouser, postdoc Max Bolot, and Research Scientist Laszlo Sarkozy, working under the direction of Associate Professor Elisabeth Moyer, have carried out direct measurements of deuterium-hydrogen isotopic fractionation during ice deposition in simulated cirrus clouds at temperatures relevant to the polar regions of Earth and the near-surface atmospheric layers of Mars. The experiments used the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) cloud chamber in Karlsruhe, Germany. The new data provide fundamental constraints that will improve confidence in the interpretation of deuterium isotopic variations in the atmospheres of both Earth and Mars. The results have been published in the Proceedings of the National Academy of Sciences.
May 11, 2017
Former DoGS postdoc and current assistant professor at Peking University Jun Yang, assistant professor Malte Jansen, and associate professor Dorian Abbot have published a new paper investigating the aftermath of snowball Earth (global glaciation) events. During a snowball Earth event about half of Earth's ocean was locked up in ice, and the remainder of the ocean was cold and salty. After the snowballs melted this cold, salty, dense layer was overlain with a warm, fresh, light layer made up of water that used to be ice. The new work shows that it took about 50,000 years for this density gradient to mix away, rather than the ~1,000 year mixing timescale of the modern ocean. This result is critical for geologists trying to understand the geochemical clues the snowball left behind.