Collaborative Research: Organic geochemical and isotopic reconstructions of North Pacific climate and sea ice variability

恢复过去的海冰覆盖是古海洋学/古气候研究中的一个基本挑战。突变的概念和数值模型以及高纬度和低纬度作为气候变化驱动因素的作用使海冰成为变化的主要原因，但迄今为止还没有可靠的过去海冰范围的替代。理解海冰在过去变化中的作用也对我们理解未来北冰洋海冰覆盖变化的后果产生至关重要的影响。这项研究校准并应用了一套新的有机生物标志物(IP25海冰指数和TEX86温度指数)来从白令海和楚科奇海的一系列高沉积速率岩心中重建海冰及其相关的海表面温度的变化。具体地说，研究人员将1)制作一个相对IP25浓度的高纬度空间数据集，并将这些化合物的分布与现代海冰范围进行比较；2)建立一个新的高纬度海洋表层沉积物中生物标记物分布的数据库，并与已知的SST变化进行比较；3)重建选定的高纬度地点在晚冰期和全新世期间季节性海冰和相关海面温度的过去变化。除了更好地了解海冰面积在气候变化中的作用的社会相关性之外，更广泛的影响还包括对博士生的支持，对本科生的暑期研究项目，以及德克萨斯大学奥斯汀分校的一名新教员。

Reconstructing past sea ice cover is a fundamental challenge in paleoceanography/paleoclimate research. Conceptual and numerical models of abrupt changes and the role of high vs. low latitudes as the drivers of climate change invoke sea ice as a principle cause of variability, but to date there have been no reliable proxies of past sea ice extent. Understanding the role of sea ice in past changes also critically impacts our understanding of the consequences of future changes in Arctic sea ice cover. This research calibrates and applies a set of new organic biomarkers (IP25 sea ice index, and TEX86 temperature index) to reconstruct changes in sea ice and associated sea surface temperatures from a series of high sedimentation rate cores from the Bering and Chukchi Seas. Specifically, the researchers will 1) produce a high latitude spatial dataset of relative IP25 concentrations and compare the distribution of these compounds with modern sea ice extent, 2) generate a new database of biomarker distributions in surface sediments from high-latitude oceans and compare with known SST variations, and 3) reconstruct past changes in seasonal sea ice and associated sea surface temperatures during the late glacial and Holocene from selected high latitude sites. In addition to the societal relevance of better understanding the role of sea ice extent in climate change, broader impacts include support of a PhD student, summer research projects for undergraduates, and a new faculty member at the University of Texas at Austin.