Creating a Database of Climate Extremes and Variability in Polar Ice Cores

Prior results from EGRIP (East Greenland Icesheet Project ice core) indicate that interannual-to-decadal variability in water isotopes lead abrupt Dansgaard-Oeschger event (D-O Events) warming by hundreds of years. As part of the U.S. National Science Foundation funded “Beyond Mean Climate” project, GISP2 (Greenland Ice Sheet Project 2 ice core) is being resampled at the NSF-Ice Core Facility and reanalyzed for high resolution water isotope measurements at INSTAAR, University of Colorado. GISP2 gives us the chance to verify those results from EGRIP and test whether the lead-lag may result from firn processes and diffusion, or from regional climate dynamics. Additionally, for part of this project we are creating a statistical database of climate variability and extremes in multiple Greenland and Antarctic ice cores. This database will include GISP2 and existing records of high-resolution water isotopes and impurities. The initial statistical database of climate indicators will include the mean, standard deviation, extreme values using the tail ends of probability distributions, and spectral analysis to determine the average amplitude in a given frequency band. We will present initial results on the first section of processed data from GISP2, as well as results from WDC (West Antarctic Ice Sheet Divide ice core), SPC (South Pole ice core), and EGRIP (East Greenland Icesheet Project ice core). In particular, we will focus on how the strength of interannual-to-decadal variability is different across geographies (Greenland, Antarctica, interhemispheric), analyze lead-lag between mean temperature and variability (e.g. for D-O Events in Greenland and their Antarctic counterparts, Antarctic Isotope Maxima (AIM) Events), and compare results across the deglaciation.