High-Resolution Constraints on the Magnitude and Timing of Climate Change in Iceland Over the Past 15 ka.

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Miller0138010This is a collaborative proposal among Principal Investigators at the Universities of Colorado and Iceland. Iceland is situated at the boundary between cold, polar air masses and relatively warm air masses of tropical origin and between the cold, relatively fresh East Greenland Current and the warm, salty North Atlantic Drift. Subtle shifts in either atmospheric or oceanic circulation may have produced strong changes in the terrestrial environment. Therefore, the impact of North Atlantic Holocene circulation variability was likely to be stronger on Iceland than most other North Atlantic landmasses. There has been a historical record of environmental change on Iceland since its settlement and the large variations observed confirm Iceland's climate sensitivity. The goal of the project is to reconstruct Iceland's large ice caps through the present interglacial and document abrupt shifts that occurred during deglaciation, and the magnitude, timing and possible cyclicity of terrestrial environmental change. The Principal Investigators will attempt to answer two specific questions: 1) did some of the extant large ice caps disappear in the early Holocene, and if so, when did they regrow and 2) what were the terrestrial and near-shore environmental conditions during deglaciation? Continuous cores from two deep, high-sedimentation-rate lake basins will be recovered. These lakes were selected because the sediments are expected to provide high-resolution, quantitative evidence of environmental change over the past 10 to 15 thousand years. The Principal Investigators will undertake a multiproxy approach, with an emphasis on physical characteristics of the sediments, lacustrine primary productivity changes, palynology, and marine micropaleontology. These data should allow them to determine whether there is a natural cyclicity in Holocene environmental change on Iceland, similar to that reported from the adjacent oceans and the Greenland Ice Sheet.