What do glaciers tell us about climate variability and climate change?
What do glaciers tell us about climate variability and climate change?
复制标题
冰川告诉我们有关气候变率和气候变化的什么信息？
作者：
G. Roe
摘要冰川对长期气候变化的反应，也对恒定气候中固有的逐年波动的反应。区分这些因素对于正确解释过去冰川波动和正确归因当前变化至关重要。以前的工作已经确定，在恒定的气候中可以发生世纪尺度的波动。这项研究进一步提出了两个具有实际意义的问题：在给定的时间内，给定幅度的偏移的可能性有多大，以及长度的趋势在统计上有多大意义？一个线性模型允许分析答案，其中依赖于冰川的几何形状和气候设置可以清楚地了解。用流线冰川模型验证了表达式的正确性。冰川漂移的可能性是很好的特点，极端值的统计，虽然概率是非常敏感的一些鲜为人知的冰川特性。常规的统计检验可用于确定观测到的冰川趋势的重要性。然而，重要的是确定观测中的独立信息，这些信息可以从冰川几何形状中有效地估计。最后，美国华盛顿州贝克山周围冰川的退缩与从仪器记录中确定的区域气候变暖是一致的，但不是独立的证据。
Abstract Glaciers respond to long-term climate changes and also to the year-to-year fluctuations inherent in a constant climate. Differentiating between these factors is critical for the correct interpretation of past glacier fluctuations and for the correct attribution of current changes. Previous work has established that century-scale, kilometre-scale fluctuations can occur in a constant climate. This study asks two further questions of practical significance: how likely is an excursion of a given magnitude in a given amount of time, and how large a trend in length is statistically significant? A linear model permits analytical answers wherein the dependencies on glacier geometry and climate setting can be clearly understood. The expressions are validated with a flowline glacier model. The likelihood of glacier excursions is well characterized by extreme-value statistics, although probabilities are acutely sensitive to some poorly known glacier properties. Conventional statistical tests can be used for establishing the significance of an observed glacier trend. However, it is important to determine the independent information in the observations which can be effectively estimated from the glacier geometry. Finally, the retreat of glaciers around Mount Baker, Washington State, USA, is consistent with, but not independent proof of, the regional climate warming that is established from the instrumental record.