RUI: Collaborative Research: Glaciation and Climate Change in the Rocky Mountains During the Last Glacial Maximum and the Subsequent Deglaciation

RUI：合作研究：末次盛冰期和随后的冰消期期间落基山脉的冰川作用和气候变化

• 批准号: 1024852
• 负责人: Benjamin Laabs
• 金额: $ 8.95万
• 依托单位: SUNY College at Geneseo
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1024852&HistoricalAwards=false
• 关键词: RUI; Collaborative; Research; Glaciation; Climate

Mountain glaciers were numerous in the Rocky Mountains of western North America during the last Pleistocene glaciation, and the geologic record of these glaciers provides dramatic evidence of climatic changes during and following the Last Glacial Maximum. This research will build upon and augment the Pleistocene mountain glacial chronologies in the U.S. Rocky Mountain region, and use these chronologies to model past climate changes. The project uses both field and analytical methods to address two broad objectives: (1) to determine the changes from modern climate that would be necessary to sustain Rocky Mountain glaciers at their last Pleistocene maximum extents, along a transect from northern Montana to south-central New Mexico, and (2) to determine the timing and rate of subsequent ice recession, and the magnitudes and rates of climate change necessary to drive that recession. The first objective involves additional glacial mapping and chronology in eight study areas, making use of cosmogenic beryllium-10 surface-exposure dating to constrain the timing and extent of glaciers during Last Glacial Maximum. A numerical model of glacier mass balance and ice flow will allow determination of the character and magnitudes of climatic change sufficient to produce the observed glacial extents. The second objective involves additional surface-exposure dating in four of the eight study areas to constrain the timing and rates of ice recession following its maximum stand, and to allow modeling of the climate changes that caused the recession. The results of this research will include a regional synthesis of glacier-climate reconstructions for the last Pleistocene glaciation and the subsequent deglaciation, an assessment of the climatic significance of the apparent variability in the timing of the Last Glacial Maximum, and an improvement in the chronology of mountain glacier movements.This application of high-resolution glacier modeling and cosmogenic-radionuclide dating methods will provide insight into the history of climate change in the Rocky Mountain region. The time interval of interest is the Last Glacial Maximum (the interval of maximum global ice volume) and the subsequent transition to the present warm period, the latter occurring over approximately 6000 years. This transition was an interval of major global warming, during which substantial changes in atmospheric circulation occurred in the western United States in response to shrinking ice sheets, increased incoming solar radiation, and rising atmospheric carbon dioxide levels. Such changes in airflow undoubtedly brought about changes in regional precipitation patterns, as is suggested by paleoclimate models. The results of this research will assess the accuracy of such models in representing precipitation patterns of the past, and may also provide insight into the accuracy of model predictions of future precipitation changes in the Rocky Mountains region, an area where demand for limited water resources continues to grow.

在最后一次更新世冰期期间，北美西部落基山脉的山地冰川数量众多，这些冰川的地质记录提供了末次盛冰期期间和之后气候变化的戏剧性证据。这项研究将建立在美国落基山脉地区更新世山地冰川年表的基础上，并利用这些年表来模拟过去的气候变化。该项目采用实地和分析方法，以实现两大目标：（1）确定从现代气候的变化，这将是必要的，以维持落基山冰川在其最后更新世的最大范围，沿着一个样带从北方蒙大拿州中南部新墨西哥州，（2）确定时间和速度，随后冰衰退，以及推动经济衰退所需的气候变化的幅度和速度。第一个目标是在8个研究地区进行更多的冰川测绘和年代学研究，利用宇宙成因铍-10表面暴露测年来限制末次盛冰期冰川的时间和范围。冰川质量平衡和冰流的数值模型将能够确定足以产生所观测到的冰川范围的气候变化的特征和幅度。第二个目标是在八个研究区域中的四个区域进行额外的表面暴露测年，以限制冰衰退的时间和速度，并允许对导致衰退的气候变化进行建模。这项研究的结果将包括一个区域综合的冰川气候重建的最后更新世冰期和随后的冰川消退，评估气候意义的明显变化的时间最后冰川，这一高分辨率冰川模拟和宇宙成因的应用，放射性核素测年方法将为深入了解落基山脉地区的气候变化历史提供帮助。感兴趣的时间间隔是末次冰盛期（最大全球冰量的间隔）和随后的过渡到现在的温暖期，后者发生在大约6000年。这一转变是全球变暖的一个重要时期，在此期间，美国西部的大气环流发生了重大变化，以应对冰盖的缩小，太阳辐射的增加和大气二氧化碳水平的上升。正如古气候模式所表明的那样，气流的这种变化无疑会引起区域降水模式的变化。 这项研究的结果将评估这些模型在代表过去的降水模式的准确性，也可能提供洞察模型预测的准确性在落基山脉地区，对有限的水资源的需求继续增长的地区未来的降水变化。