Thursday, November 03, 2011, 4:30AM - 5:30AM
Full title of talk: "Muddy Waters and the Arctic Blues: Reconstructing climate and glaciers from Icelandic lake sediments."
Iceland is totally extreme. Shaped by volcanism and molded by glacier ice, the island is an active geological wonderland that uniquely marries tectonic and geomorphologic processes in an arena the size of Colorado (~103,000 km2). Positioned in a region of strong thermal gradients, Iceland is the largest landmass in the central North Atlantic and is well situated to monitor Holocene climate variability and associated changes in ocean and atmospheric circulation. Terrestrial climate there has been reconstructed from a variety of geologic sources but remains coarsely resolved and/or incomplete. In particular, information on past glacier activity is fragmentary and primarily relies on dated moraine complexes, which are inherently limited and temporally discontinuous. Temperate glaciers presently cover ~10% of the island and are sensitive to climate variability, yet little is known about their evolution through the Holocene. This talk will focus on recent work aimed at unraveling the Holocene climate and glacier evolution of the central Iceland highlands. Laminated sediments from the proglacial lake Hvítárvatn provide a continuous record of environmental change and the development of the adjacent Langjökull ice cap for the past ~10.2 ka. Multiple glacier and environmental proxies are placed in a secure geochronology with annual to multi-decadal resolution, and reveal a dynamic Holocene terrestrial climate, characterized by non-linear behavior and high magnitude changes. Emphasis will be placed on the behavior of Langjökull outlet glaciers during the Little Ice Age, when most Icelandic glaciers attained their maximum Holocene extent. Photographs of the central highlands, taken over multiple field seasons, will be included to keep things interesting for all.