Holocene and Anthropocene sea-level records from Indonesia

全新世的海平面变化在地理上是多变的。对观测到的变率负责的大尺度机制包括由极地冰盖和海洋之间的冰川后物质交换引起的浮力融水贡献和固体地球均衡调整之间的相互作用。这些过程通过作用于较短时间尺度和受区域限制的海洋学因素进一步细化。在全新世早期，赤道海洋盆地的海平面一直在迅速上升，这反映了远离冰原的主要上升作用。在全新世中期，当冰盖融化速度减缓时，均衡作用成为控制热带地区海平面变化的主要因素，因为高纬度地区外围隆起的沉降导致水团从赤道向两极重新分布。在全新世/人类世晚期，热带海平面的变化在很大程度上是由动态海洋学和空间因素决定的。了解远场全新世海平面变化的主要驱动因素之间的时空相互作用，对于理解过去的冰盖动力学、限制冰川均衡调整模式中的地球参数和评估人为影响至关重要。该项目有助于了解印度尼西亚全新世/人类世海平面变化的主要驱动因素，印度尼西亚是一个非常容易受到未来海平面上升影响的群岛。我们将根据苏拉威西岛构造稳定的Spermonde群岛的珊瑚礁岩心重建，确定全新世早期海平面上升的速度和海平面首次达到当前位置的时间。结果将与一系列冰川均衡调整模拟结果进行比较，以便发现均衡贡献在哪个时间点成为全新世早期海平面上升的主要驱动力。该项目将进一步验证苏拉威西岛西南部现有的全新世中期海平面重建，通过对使用的海平面指标的来源进行彻底的实地评估，其特点是存在很大的不一致性。结合全新世早期重建，这些结果将用于对区域地球模式参数进行精确约束，并为正在进行的人为和动态海洋学贡献提供可靠的均衡背景信号。最后，该项目将提供东南亚全新世/人类世晚期的第一个高分辨率海平面记录，该记录基于可追溯到17世纪的平板微型环礁的浮动年表。这一独特的记录将用于评估小冰期和20世纪全球变暖期间印度-太平洋暖池对海平面变化的空间贡献。

Sea-level changes through the Holocene have been geographically variable. Large-scale mechanisms responsible for the observed variability comprise the interplay between eustatic melt-water contributions and isostatic adjustments of the solid Earth resulting from postglacial mass exchange between polar ice sheets and the oceans. These processes are further nuanced through oceanographic factors that act on shorter time scales and regionally constrained. During the early Holocene, sea level has been rising rapidly in equatorial ocean basins, reflecting a dominant eustatic contribution far from the ice sheets. In the middle Holocene, when melting of ice sheets slowed down, isostasy became the dominant control on sea-level changes in the tropics as subsiding peripheral forebulges in higher latitudes induced a redistribution of water masses away from the equator towards the poles. In the late Holocene / Anthropocene, tropical sea-level variability has been largely determined by dynamic oceanographic and steric factors. Knowledge of the spatial and temporal interplay between the dominant drivers of Holocene sea-level changes in the far field is essential to understand past ice sheet dynamics, constrain Earth parameters in glacial isostatic adjustment models and evaluate anthropogenic influences. This project contributes to the understanding of the dominant drivers of Holocene / Anthropocene sea-level changes in Indonesia, an archipelago that is highly vulnerable to future sea-level rise. We will determine the rate of early Holocene sea-level rise and the timing when sea level first reached its present position from reconstructions based on coral reef drill cores in the tectonically stable Spermonde Archipelago, Sulawesi. Results will be compared to an ensemble of glacial isostatic adjustment simulations in order to detect at which point in time isostatic contributions became the dominant driver of early Holocene sea-level rise. This project will furthermore validate existing mid-Holocene sea-level reconstructions for southwest Sulawesi, which are characterized by large inconsistencies, through a thorough field evaluation of the origins of the used sea-level indicators. In combination with the early Holocene reconstructions, these results will be used to put precise constraints on the regional Earth model parameters and to provide a reliable isostatic background signal to the ongoing anthropogenic and dynamic oceanographic contributions. Lastly, this project will provide the first high-resolution sea-level record for the late Holocene / Anthropocene in Southeast Asia, based on floating chronologies from slabbed microatolls reaching back in time to the 17th century. This unique record will be used to evaluate the steric contribution on sea-level variability in the Indo-Pacific Warm Pool during the Little Ice Age and the 20th century global warming.