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.

在末次更新世冰川作用期间，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区冰川年表的基础上并对其进行扩充，并利用这些年表来模拟过去的气候变化。该项目使用实地和分析方法来实现两个广泛的目标：（1）确定现代气候的变化，这是维持落基山冰川在最后更新世最大范围（沿着从蒙大拿州北部到中南部的横断面）所必需的。新墨西哥州，以及（2）确定随后冰衰退的时间和速率，以及推动该衰退所需的气候变化的幅度和速率。第一个目标涉及八个研究区域的额外冰川测绘和年代学，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观测到的冰川范围的气候变化的特征和幅度。第二个目标涉及在八个研究区域中的四个区域进行额外的地表暴露测年，以限制冰在其最高水平后退缩的时间和速率，并允许对导致退缩的气候变化进行建模。这项研究的结果将包括对末次更新世冰川期和随后的冰消期的冰川气候重建的区域综合、对末次盛冰期明显变化的气候意义的评估以及年代学的改进高分辨率冰川建模和宇宙成因放射性核素测年方法的应用将有助于深入了解落基山脉地区的气候变化历史。感兴趣的时间间隔是末次盛冰期（全球冰量最大的时间间隔）以及随后过渡到当前温暖期的时间间隔，后者发生在大约 6000 年的时间里。这一转变是全球变暖的一个时期，在此期间，由于冰盖缩小、太阳辐射增加和大气二氧化碳水平上升，美国西部大气环流发生了重大变化。正如古气候模型所表明的那样，气流的这种变化无疑带来了区域降水模式的变化。 这项研究的结果将评估此类模型在代表过去降水模式方面的准确性，并且还可以深入了解落基山脉地区未来降水变化的模型预测的准确性，该地区对有限水资源的需求仍在继续成长。