Origin of Millennial-scale Climate Signals in the Northwestern Subtropical Atlantic

千年尺度的气候变化是否与地球轨道的变化(以及太阳对地球表面的影响的时间和分布)有关的问题已有几十年的历史，但在气候变化科学界仍然是一个有争议的话题。这项研究由特拉华大学的一名科学家领导，调查了在更新世期间，随着轨道进动周期的变化，短期气候变化是如何演变的，重点是过去90万年。中心假设是，西北部副热带大西洋千禧年尺度的气候信号与外部驱动因素有关，特别是岁差的四次谐波。如果热带太阳强迫控制着千年尺度的变率，那么四次谐波(4800年)峰值的频谱功率应该会减少，因为19000年的进动频率在大约34万年前消失了。作为验证这一假说的先决条件，这项工作将填补布莱克-巴哈马外脊稳定氧同位素记录中的一个关键空白，完成布莱克外脊长达140万年的浮游有孔虫稳定同位素记录。这实现了大洋钻探计划腿172的主要目标。在更广泛的影响方面，这项研究将提供有关自然气候变异性的重要信息，并将通过首席科学家的公开陈述传播结果。资助也支持硕士研究生。

The question of whether millennial-scale climate changes are related to changes in the Earth's orbit (and thus the timing and distribution of solar influence on the Earth's surface) is decades old, but remains the subject of debate in the climate change science community. This research, led by a scientist at the University of Delaware, investigates how short-term climate variability evolved as the periodicity of orbital precession has changed through the Pleistocene, focusing on the last 900,000 years. The central hypothesis is that millennial-scale climate signals in the northwestern subtropical Atlantic are linked to external driving factors, specifically the fourth harmonic of precession. If tropical insolation forcing controls millennial-scale variability, then there should be a reduction in the spectral power of the fourth harmonic (4,800 year) peak as the 19,000 year precession frequency disappears after about 340,000 years ago. As a prerequisite for testing the hypothesis, the work will fill a key gap in the stable oxygen isotope record from the Blake-Bahama Outer Ridge, completing a 1.4 million year long planktonic foraminifer stable isotope record from the Blake Outer Ridge. This fulfills a primary objective of Ocean Drilling Program Leg 172. In terms of broader impacts, the research will provide important information about natural climate variability, and results will be disseminated through public presentations by the lead scientist. Funding also supports a Master's degree student.