Collaborative Research: Investigating Southern Ocean Sea Surface Temperatures and Freshening during the Late Pliocene and Pleistocene along the Antarctic Margin

非技术：随着南极洲冰盖的融化，淡水进入海洋，这可能会增加冰盖附近的海冰覆盖。海冰的形成改变了海水的密度，从而调节了全球海洋的水循环。海冰扩张也可能减缓推动冰盖融化的过程。这项研究将从邻近以及离冰缘更远的海域恢复的地质记录中检验海洋表面冷却和海洋新鲜之间的关系。这些记录将提供关于在消冰过程中海冰扩张的作用的关键信息。地质记录跨越了气候条件与预测的未来变暖情景相似的时间间隔。因此，这些新记录将为近期（100年）和长期（100年）未来冰盖融化和海洋表面变新鲜的后果提供视角。更广泛的影响将包括对本科生研究人员的培训，通过时间拾荒者网站和实践社区科学活动传播研究成果，以及与学校教师和学生的接触。技术说明：在过去的几十年里，海洋变暖和南极冰盖的损失导致了南大洋罗斯海部分的海面变新鲜。海洋表面变新鲜与海冰扩张有关，海冰扩张在调节全球海洋环流方面具有重要作用，并且被认为是减缓海冰退缩的负气候反馈。由于仪器记录的短期性质，对南大洋变暖、冰架融化、海洋表面新鲜、海冰增长和深水形成所涉及的强迫和反馈仍然知之甚少。本研究的目的是：(1)利用ANDRILL和1b以及国际海洋发现计划（IODP） U1524的沉积物岩心档案，在冰期和间冰期的冰近端和冰边缘环境下，生成多指标的上新世-更新世海面温度和融水变化记录；(2)研究上新世-更新世海面温度和融水变化的外部强迫机制和轨道节奏。该项目的结果旨在更好地了解在最近地质历史的不同气候情景下海洋冰盖驱动的动力学。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。

Non-technical: As Antarctica’s ice sheets melt, freshwater enters the ocean, which can increase sea ice cover adjacent to the ice sheet. Sea ice formation changes the density of sea water thus regulating the circulation of water throughout the global ocean. Sea ice expansion may also slow down the processes driving ice sheet melt. This research will examine the relationship between surface ocean cooling and ocean freshening from geological records recovered adjacent, as well as farther seaward from the ice margin. These records will provide key information regarding the role in sea ice expansion during the process of deglaciation. The geological records span time intervals when climate conditions were similar to predicted future warming scenarios. Therefore, these new records will provide perspective on what the consequences of an ice sheet melting and surface ocean freshening might be in the near-term (100 years) and long-term (100-years) future. Broader impacts will include training for undergraduate researchers, dissemination of research findings through the Time Scavengers website and hands-on community science events, and engagement with school teachers and students. Technical Description: Ocean warming and Antarctic ice mass loss over the last few decades has resulted in surface freshening in the Ross Sea sector of the Southern Ocean. Surface ocean freshening is linked to sea ice expansion, which has an important role in regulating global ocean circulation and is hypothesized to be a negative climate feedback slowing ice retreat. The forcings and feedbacks involved in Southern Ocean warming, ice shelf melt, surface ocean freshening, sea ice growth, and deep water formation remain poorly understood due to the short-term nature of instrumental records. The objective of this research program is to: (1) generate multi-proxy Plio-Pleistocene sea surface temperature and meltwater records in ice-proximal and ice-marginal settings during deglacial and interglacial intervals from archived sediment cores of ANDRILL AND-1B as well as International Ocean Discovery Program (IODP) U1524, and (2) examine the external forcing mechanisms and orbital pacing of sea surface temperature and meltwater variability during the Plio-Pleistocene. Results from this project aim to better understand ocean-ice sheet driven dynamics under varying climate scenarios of the most recent geological past.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.