Collaborative Research: Improved Constraints on Holocene Retreat History of the Laurentide and Scandinavian Ice Sheets from Cosmogenic Dating and Implications for Sea-level Rise

合作研究：从宇宙成因年代测定和海平面上升的含义改进了对劳伦泰德和斯堪的纳维亚冰盖全新世退缩历史的限制。卡尔森（U.（Wisconsin-Madison）克拉克（俄勒冈州州立大学）冰盖与气候研究的主要目标是了解冰盖对气候变化的响应。确定过去冰盖退缩的速度和在自然比现在更温暖的气候下对海平面上升的贡献，为未来格陵兰冰盖对全球变暖的反应提供了背景。 在这里，这个研究小组提出，以改善冰川消退年表和调查的劳伦泰德（LIS）和斯堪的纳维亚（SIS）冰盖的退缩率在早至中期全新世（11.7 ka），一段时间，提供了一个很好的自然实验，这些陆地冰盖冰川消退下的气候比现在温暖，但可能类似于本世纪结束。该项目提出直接日期的撤退东南部和东部LIS的边缘和南部，东部和北方SIS的边缘在全新世早期至中期使用现场宇宙成因的表面暴露年龄，显着提高了最大的LIS圆顶和大多数SIS的年表。由此产生的年表将结合现有的宇宙成因年表从西部魁北克，东北拉布拉多和芬兰南部，现有的最低限度放射性碳日期和纹记录。 这些数据将允许计算LIS和SIS撤退率和海平面上升的贡献在全新世早期至中期，其余的海平面上升主要归因于南极冰盖。 这些结果将提供对辐射强迫下冰盖融化的自然速率的估计，这可能类似于本世纪末的气候。 更广泛的影响鉴于预测未来海平面上升对全球变暖的反应的最大不确定性是剩余冰盖的贡献，在比现在更温暖的气候下限制融化速度至关重要。 这项研究的结果将为气候科学家提供在自然比现在更温暖的气候下陆地冰盖的退缩率和随之而来的海平面上升贡献的估计。 从这项研究中获得的信息将对政策决定具有重要意义，并对广泛的地球科学家和公众感兴趣。 该研究计划将支持2个博士学位。学生将接触到多学科的科学方法，包括古气候学，冰川地质学，宇宙成因同位素地球化学和古海洋学。它还将为一个非终身制的，早期的职业助理教授提供支持，促进他的学术生涯。

Collaborative Research: Improved constraints on Holocene retreat history of the Laurentide and Scandinavian Ice Sheets from cosmogenic dating and implications for sea-level riseAnders E. Carlson (U. of Wisconsin-Madison) EAR-0958872 Peter U. Clark (Oregon State U.) EAR-0958714ABSTRACTA major objective of ice sheet and climate research is to understand the responses of ice sheets to climate change. Ascertaining the past rates of ice-sheet retreat and contributions to sea-level rise under climate that was naturally warmer than present provides context for the future Greenland Ice-Sheet response to global warming. Here, this research team proposes to improve the deglacial chronologies and investigate retreat rates of the Laurentide (LIS) and Scandinavian (SIS) Ice Sheets during the early to mid-Holocene (11.7 ka), a period of time that provides an excellent natural experiment where these terrestrial ice sheets deglaciated under a climate warmer than present but potentially similar to the end of this century. This project proposes to directly date the retreat of the southeastern and eastern LIS margins and the southern, eastern, and northern SIS margins during the early to mid-Holocene using in situ cosmogenic surface exposure ages, significantly improving the chronology for the largest of the LIS domes and the majority of the SIS. The resulting chronologies will be combined with already existing cosmogenic chronologies from western Quebec, northeastern Labrador and southern Finland, and existing minimum limiting radiocarbon dates and varve records. These data will allow calculations of LIS and SIS retreat rates and sea-level rise contributions during the early to mid-Holocene, with the remainder of sea-level rise largely attributable to the Antarctic Ice Sheet. The results will provide estimates of the natural rates at which ice sheets can melt under radiative forcing that may be analogous to the climate of the end of this century. Broader ImpactsGiven that the greatest uncertainty in predicting future sea-level rise in response to global warming are the contributions from the remaining ice sheets, it is critical to constrain melt rates under warmer than present climates. Results of this research will provide climate scientists with estimates of the retreat rates and attendant sea-level rise contributions from terrestrial ice sheets under a climate naturally warmer than present. The information gained from this research will be of significant importance for policy decisions and of interest to a broad range of earth scientists and the public in general. This research proposal will support 2 Ph.D. students who will be exposed to a multi-disciplinary scientific approach that includes paleoclimatology, glacial geology, cosmogenic isotope geochemistry and paleoceanography. It will also provide support for an untenured, early career Assistant Professor furthering his academic career.