Regional climatic controls on the growth, configuration and decay of the northern cordilleran ice sheet

区域气候对北部科迪勒拉冰盖的生长、构造和衰变的控制

• 批准号: 216911-2009
• 负责人: Ward, Brent
• 金额: $ 1.46万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=424705
• 关键词: Regional; climatic; controls; growth; configuration

Climate change continues to be a global priority. Predictive models require reliable, long term, paleoclimate data to evaluate the accuracy of future predictions. The proposed research will provide paleoclimate data from Yukon Territory. This area is unique in Canada because of its glaciated surfaces of great antiquity and large unglaciated area that forms the eastern limit of Beringia. These glaciated surfaces were repeatedly affected by a glacier complex termed the northern Cordilleran Ice Sheet. The record of this ice sheet prior to 40 000 years is relatively poorly constrained. Across most of Canada, old glacial surfaces are covered in drift. In contrast, their exposure at the surface in Yukon allows us to use innovative dating techniques (such as Terrestrial Cosmogenic Nuclide exposure dating) to determine the age of the last ice cover. This helps us define periods of colder than present conditions, when glaciers covered much more of the landscape than during the last glacial period. Sediments relating to non-glacial periods located below and on top of these old glaciated surfaces can be examined for plant and insect fossils. By comparing these fossils to their present distribution, the paleoclimate can be estimated. Some of these non-glacial periods were warmer than present and can serve as a good analog for future global warming. In this instance, the past could be the key to the future. These non-glacial sediments can sometime be dated by the presence of volcanic ash beds, similar to what was produced by Mt. St. Helen's. Dating these glacial and non-glacial deposits is the most effective method of determining how climate change affect Yukon for the past 200,000 to 300,000 years.

气候变化仍然是全球优先事项。预测模型需要可靠的长期古气候数据来评估未来预测的准确性。拟议的研究将提供育空地区的古气候数据。该地区在加拿大是独一无二的，因为其古老的冰川表面和形成白令陆桥东部边界的大片非冰川区域。这些冰川表面反复受到称为北部科迪勒拉冰盖的冰川复合体的影响。该冰盖 4 万年前的记录相对较少。在加拿大大部分地区，古老的冰川表面都覆盖着漂移物。相比之下，它们在育空地表的暴露使我们能够使用创新的测年技术（例如陆地宇宙成因核素暴露测年）来确定最后一个冰盖的年龄。这有助于我们定义比现在更冷的时期，此时冰川覆盖的地貌比上一个冰河时期要大得多。可以检查位于这些古老冰川表面下方和顶部的与非冰川期有关的沉积物中的植物和昆虫化石。通过将这些化石与其目前的分布进行比较，可以估计古气候。其中一些非冰川时期比现在温暖，可以作为未来全球变暖的一个很好的类比。在这种情况下，过去可能是未来的关键。这些非冰川沉积物有时可以通过火山灰床的存在来确定年代，类似于圣海伦火山产生的火山灰床。对这些冰川和非冰川沉积物进行年代测定是确定过去 20 万至 30 万年气候变化如何影响育空地区的最有效方法。