Dust Barnes Ice Field

Climate models of the Intergovernmental Panel on Climate Change (IPCC) project a cluster of abrupt shifts under a 1.5C - 2.0C global warming scenario as being a global threat to civilization. However, regime shifts are hard to predict due to limited understanding of feedbacks in the climate system, in particular the role of atmospheric dust. Abrupt warming/cooling episodes (Dansgaard-Oeschger events, DO), are recorded in Greenland ice cores in tandem with large dust concentration and particle size variations, indicating that the climate of continental sources and Greenland must have been coupled. DO events also influenced Eurasian dust activity, implying large-scale abrupt changes in dustiness during DO events, with causal relationships and climate impacts remaining largely unclear. Greenland ice cores are currently the only archives of large scale dustiness, but are geographically restricted, preventing understanding of the role of different atmospheric dust dispersion patterns and climatic consequences. As a remnant of the Laurentide Ice Sheet, the Barnes Ice Cap (BIC, Baffin Island, Canadian Arctic) has great potential in filling this gap. Proxy records to be obtained from BIC, located on potential dust transport pathways to Greenland, will provide insights into DO warming/cooling in continental North America, the timing and strength of related dust events, transport characteristics and dust emitting regions. Sampling of BIC allows 14C-dating of organic carbon from ice and generation of a robust age model for the proxy records. Combined use of the Hf-Sr-Nd isotope tracers on aerosols recovered from large ice blocks through surface sampling at BIC enables source identification for multiple dust samples and tracking of dust source changes over the LGM and early Holocene. Isotopic analyses of this kind requires specific sample decomposition method and ion exchange chemistry setup, which our team recently established. The 14C-dated multi-proxy records from BIC have the potential to test models of LGM atmospheric circulation over the Northern Hemisphere, allowing precise paleoclimate interpretations of ice core records and providing new insight into past dust-climate feedbacks. Improved climate models will capture a richer suite of couplings and feedbacks in the Earth system and have better abilities to properly simulate past abrupt climate changes, thereby increasing confidence in their ability to project such events for the future.