Investigation of Greenland and Antarctic Ice Core Recorded Climate Change Using Ultra-High Resolution Sampling

Advances in instrumentation and sampling techniques in recent years have allowed for increasingly lower detection capabilities and finer sampling resolutions for ice core records, improving our understanding of the mechanisms of past climate change. We refine interpretations of select paleoclimate records in polar ice cores through the use of a new ultra-high resolution (121 μm) non-destructive sampling method that achieves a temporal resolution of hundreds of samples per year using laser ablation inductively coupled plasma mass spectrometry (LA-ICP- MS). We measure concentrations of select glaciochemical species, proxies for atmospheric circulation from both an Arctic (GISP2) and Antarctic (Siple Dome) ice core archive.In the Arctic ice core archive, we offer the first sub-seasonal view of a glacial age abrupt climate change event. We focus on the abrupt ~84.5 ka climate transition from cold stadial to warmer interstadial conditions originally captured in the Greenland Ice Sheet Project 2 (GISP2) ice core records for stable water isotopes, soluble major ion records (IC), laser light scattering (LLS), and electrical conductivity measurements (ECM). We utilize the ultra-high resolution capabilities of a newly developed laser ablation- inductively couple plasma- mass spectrometry (LA-ICP-MS; 121 μm sampling resolution) system capable of conducting multi-parameter glaciochemical analysis. This is the oldest ice core sample thus far analyzed using this technique. Resulting ultra-high resolution data demonstrates that: (1) net summer and winter accumulation rates nearly double with entry into the interstadial, (2) summer storm frequency increases with entry into the interstadial, (3) the westerlies and Siberian High weaken with entry into the interstadial, while the strength of the Icelandic Low remains fairly constant, and (4) there are potentially valuable insights regarding the nature of abrupt climate change and very high resolution datasets.In the Antarctic ice core archives, we offer the first sub-seasonal view of glacial age archives from the Siple Dome-A (SDMA) ice core using LA-ICP-MS. Our ultra-high resolution data demonstrates that: (1) the SDMA ice core record can be annually dated based on seasonality in chemical inputs at a depth not previously possible using previous glaciochemical sampling methods, (2) winter accumulation at the Siple Dome site was greater than summer accumulation during the three late glacial periods selected (~15.3, 17.3, 21.4 thousand years ago) in this study, and (3) resulting annual layer thicknesses are not entirely consistent with the current Siple Dome ice core depth-age model, suggesting that modifications may be needed for the depth-age scale, or that depositional effects such as wind scouring, or decadal variability in snow accumulation is not captured by the current depth-age model.