Ocean Response to Prolonged Common Era Surface Climate Trends

在过去的100年里，地球表面普遍变暖，但海洋通过吸收原本会留在大气中的热量，减缓了这种变暖。最终，大气温度的变化将影响整个海洋，包括深海。但我们目前还没有足够的观测来知道深海是否能继续起到抑制地表变暖的作用。这个项目试图通过过去的观测和模型来了解海洋是如何对长期的表面变化做出反应的。该小组将从海底沉积物中生成和收集与过去2000年海洋温度变化有关的证据，并用包括深海在内的海洋环流模型解释其原因。更好地估计深海储存的热量如何影响地表气候，将推动气候科学的发展。这个项目将支持教育。它将包括一名研究生，并通过几个当地组织进行社区外展。该项目的结果还将为改善21世纪及以后的气候预测提供有关海洋影响的信息，从而造福社会。技术描述：过去2000年地表气候的长期趋势，如中世纪气候异常和小冰期之间600年的降温趋势。关键的问题是，海洋是如何对持续的表面温度趋势做出反应的？这个问题很难回答，因为在工业革命之前，对区域表面和深海温度的观测很少。该小组将利用已发表的和新的海洋沉积物观测结果，研究过去2000年来深海对地表气候变化的反应。他们将在北大西洋深水地层附近以及下游大西洋、印度洋和太平洋的深水区工作。重点是提供百年尺度区域温度变化的约束条件。这将通过观察底栖生物d18O、表面温度和底水温数据来实现。通过将温度资料同化到海洋环流模式中，重建全球海洋温度的共同时代演变。该项目将提供相对于上层海洋的深海热含量变化的估计。它还将估算两极放大和半球间气候变化时间的差异。这些结果将用于测试深海的热量损失是否可以抵消上层海洋的全球热量增加。它们还将用于评估从耦合气候模型得出的热吸收估计，并提出小冰河期的残余影响是否可能仍在影响今天的海洋。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Earth’s surface has generally warmed over the past 100 years, but the ocean has slowed this warming by taking up heat that otherwise would have remained in the atmosphere. Eventually, changes in the temperature of the atmosphere will affect the entire ocean, including the deep ocean. But we currently do not have enough observations to know whether the deep ocean can continue to act as a brake on surface warming. This project seeks to understand how the ocean responds to prolonged surface changes by using observations and models of the past. The team will generate and collect evidence from sea floor sediments related to ocean temperature changes of the last 2,000 years and interpret their causes with an ocean circulation model that includes the deep ocean. Climate science will be advanced by better estimates of how heat stored in the deep ocean affects surface climate. This project will support education. It will include a graduate student and community outreach through several local organizations. The results of the project will also benefit society by providing information about the influence of the ocean that is needed to improve climate projections of 21st century and beyond.Technical Description: The last 2,000 years is marked by long-term trends in surface climate, such as a 600-year cooling trend between the Medieval Climate Anomaly and the Little Ice Age. The key question is, how does the ocean respond to prolonged surface temperature trends? This question is difficult to answer because there are few observations of regional surface and deep ocean temperature before the Industrial Revolution. The team will use published and new observations from marine sediment that make it possible to investigate the deep ocean response to surface climate changes during the last 2,000 years. They will work on sites near North Atlantic Deep Water formation, and downstream in the deep Atlantic, Indian, and Pacific Oceans. The focus is to provide constraints on centennial-scale regional temperature variability. This will be achieved with observations of benthic d18O, surface temperature, and bottom water temperature data. The Common Era evolution of global ocean temperature will be reconstructed by assimilating temperature data into an ocean circulation model. The project will provide an estimate of changes in deep ocean heat content relative to the upper ocean. It will also estimate polar amplification and the difference in the timing of climate shifts between hemispheres. These results will be used to test whether heat loss in the deep ocean can offset global heat gain in the upper ocean. They will also be used to evaluate heat uptake estimates from coupled climate models, and to suggest whether it is possible for a remnant influence of the Little Ice Age to still be influencing the ocean today.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.