Origin of the 100-kyr Climate Cycle: Isolating Temperature and Ice Volume, 0-2Ma.

根据这一奖项，PIS将测试关于100 KYR气候周期起源的假设-过去1 Ma地球气候系统的主要特征。这些知识是理解全球地球系统内部运作的基础。PI将使用详细的氧同位素和镁/钙古温度估计来反卷积过去200万年来d18O上的冰量和温度成分的历史，这一转变时间通常被称为“中更新世转变”(MPT)。在此之前，底栖有孔虫的氧同位素数据显示，气候以41KYR为主，随后相对突然地开始了100KYR的循环，一直持续到现在。温度和冰量在这一过渡期间以及在MPT前后相对稳定的区域中的相对影响尚不清楚。对100KYR气候循环起源的假设的测试，无论是冰动力学、表层侵蚀、二氧化碳逐渐变化还是热带触发的结果，都依赖于将海洋同位素主要解释为冰量记录。这一解释现在存在疑问，因此，对这些假说的真实检验有待开发出更可靠的全球冰量记录。作为温度代理，PI将使用一种名为流动时间分辨分析(FT-TRA)的新的创新方法来分析镁/钙，这种方法几乎消除了污染物相的影响，并提供了对D18O分析的同一物种有孔虫的钙化温度估计的精确度和准确性。他们将把我们的分析重点放在两个新的钻探地点上，这两个地点是由ODP202航段发现的。这些站点(1238和1242)位于热带太平洋东部的“凉舌”和“暖池”，位于监测太平洋中央水的水深。

Under this award the PIs will test the hypotheses regarding the origin of the 100-kyr climate cycle - the dominant feature of Earth's climate system over the past ~1 Ma. This knowledge is fundamental to understanding the inner workings of the global Earth system. The PIs will employ detailed oxygen isotope and Mg/Ca paleotemperature estimates to deconvolve the history of the ice-volume and temperature components on d18O over the past two million years, a time of transition commonly referred to as the "Mid-Pleistocene Transition" (MPT). Prior to that time, benthic foraminiferal oxygen isotope data reveal a dominant 41-kyr climate, followed by a relative abrupt onset of a 100-kyr cycle that persists to the present. The relative influence of temperature and ice volume across this transition, and in the relatively stationary regimes before and after the MPT, remains unknown. Tests of hypotheses on the origin of the 100 kyr climate cycle, whether a result of ice dynamics, regolith erosion, gradual CO2 change, or tropical triggering, have relied on interpretation of the marine isotopes as primarily an ice volume record. This interpretation is now in questions and thus, true tests of these hypotheses await the development of more reliable records of global ice volume. As a temperature proxy the PIs will analyze Mg/Ca using a new and innovative method called flow through time resolved analysis, or FT-TRA which virtually eliminates effects of contaminant phases and provided precision and accuracy of estimates of calcification temperature in the same species of foraminifera analyzed for d18O. They will focus our analyses on two new drill sites, recovered by ODP Leg 202. These sites (1238 and 1242) are placed in the eastern tropical Pacific "cool tongue" and "warm pool", and are at water depths situated to monitor Pacific Central Water.