Collaborative Research: P2C2--Multi-proxy Reconstructions of North Pacific Decadal Variability from Bivalve Mollusks and Trees

该项目有三个主要的科学目标：1)将北太平洋年代际变化的工业化前范围作为基准，与20世纪观测到的模式以及模拟的古和未来半球气候数据集进行比较；2)解决尚未解决的问题，即北太平洋年代际变化的现有树轮重建之间的一致性较差，以及海洋和陆地系统之间的联系随着时间的推移在特征和强度上发生变化的可能性；3)通过比较重建的北太平洋年代际变化和独立重建的厄尔尼诺南方涛动，研究北太平洋和热带太平洋之间的长期联系。北太平洋的年代际变化在北美西部的社会经济和环境动态中起着基本作用，对渔业生产、森林生长、野火、干旱和积雪具有明确的影响。历史上，地球气候系统的这种主要模式被描述为太平洋年代际涛动，亚洲、澳大利亚和南美洲的生物和物理指标，甚至全球范围内海平面和表面温度的趋势都确定了这种振荡的特征。然而，它在公元1900年之前的行为仍然存在相当大的和长期的不确定性，以及20世纪的动态在数百年的背景下是非典型的程度。在这项研究中，将整合三个古气候代理数据源来重建北太平洋的年代际变化。首先，将从长寿海洋双壳类太平洋地鸭(Panopea Generosa)的生长增量宽度产生一个准确年代的网络，其生长被证明对海洋表面温度高度敏感。地质鸭子中的放射性碳(14C)数据，一旦交叉定年并放置在适当的历年，将为北太平洋十年变化提供另一种视角，并提供关于水团年龄和沿海海洋环流的长期变化的信息。最后，来自北太平洋边缘的现有树轮年表将与地鸭数据相结合，以多代理方法最大化重建能力和准确性。更广泛的影响涉及对早期职业科学家、研究生和博士后的支持，并将使本科生参与研究活动。这项研究旨在提供对PDO变异性、区域年轮记录差异的原因、过去本地文化和渔业的环境设置以及对海洋水库影响的见解。如果实现，这些将是重要的科学影响。该提案有一定的风险因素，但这种风险被新的科学理解中的潜在好处所抵消。

This project has three main scientific goals aimed at: 1) benchmarking pre-industrial ranges of North Pacific decadal variability for comparison to observed 20th century patterns as well as modeled paleo and future datasets of hemispheric climate; 2) addressing unresolved questions regarding poor agreement among existing tree-ring reconstructions of North Pacific decadal variability and the possibility that linkages across marine and terrestrial systems vary in character and strength over time; and 3) examining long-term linkages between the North Pacific and tropical Pacific by comparing reconstructions of North Pacific decadal variability to independent reconstructions of the El Nino Southern Oscillation.Decadal-scale variability in the North Pacific Ocean plays a fundamental role in the socioeconomic and environmental dynamics of western North America with clearly established implications for fisheries production, forest growth, wildfire, drought, and snowpack. This major mode of Earth's climate system has historically been characterized as the Pacific Decadal Oscillation for which signatures have been identified in biological and physical indicators across Asia, Australia, and South America and even in global-scale trends in sea level and surface temperature. However, there remains considerable and long-standing uncertainly in its behavior prior to AD 1900 and the extent to which 20th century dynamics are atypical in a multi-centennial context. In this study, three paleoclimate proxy data sources will be integrated to reconstruct North Pacific decadal variability. First, a network of exactly dated chronologies will be produced from growth-increment widths of long-lived marine bivalve Pacific geoduck (Panopea generosa), the growth of which is demonstrated to be highly sensitive to sea surface temperatures. Radiocarbon (14C) data in geoducks, once cross-dated and placed in the appropriate calendar years, will yield another perspective on North Pacific decadal variability with information regarding long-term changes in water mass age and coastal ocean circulation. Finally, existing tree-ring chronologies from the North Pacific rim will be integrated with the geoduck data to maximize reconstruction power and accuracy in a multi-proxy approach.The broader impacts involve support for an early career scientist, grad student, and post-doc, and will involve undergraduate students in the research activities. The research aims to provide useful insights into PDO variability, the reasons for divergence among regional tree ring records, the environmental settings of native cultures and fisheries in the past, and insights into marine reservoir effects. If achieved, these would be important scientific impacts. The proposal has an element of risk but that risk is offset by the potential benefit in new scientific understanding.