Climate change/variability and freshwater-ice systems

淡水冰是寒冷地区湖泊和河流的组成部分，也是相关生物、化学和物理过程的重要调节器。尽管人们对气候变化对冰盖系统的影响表示了严重关切(例如，政府间气候变化专门委员会和北极气候影响评估最近的评估)，但对这种系统的知识相对薄弱，很难预测气候变化影响的性质。这个项目将侧重于通过解决三个研究领域来填补我们一些最重要的知识空白：极端水文事件；气候控制；以及对水生态系统的影响。极端水文事件的焦点将是河冰破裂和相关的冰塞。这些事件可能会产生超过公开水域期间类似流量下可能发生的洪水。尽管溃决洪水已知会造成重大的经济损失，也对水生系统的环境健康至关重要，还没有对其重要性进行广泛的评估。这项研究将通过对溃决洪水的历史频率和规模进行全国和环极评估来填补这一空白，并将结果与开放水域时期的评估结果进行比较。这将为改进基础设施规划和环境管理提供基础，也是本研究计划第二个目标的基础：预测此类极端事件的频率和规模将如何受到未来气候变化的影响。河流和湖泊生态的主要变化，特别是包括水质，预计也是气候引起的河冰覆盖变化的结果。然而，预测的生态变化主要是基于对冰盖变化的猜测，而不是基于物理模型的结果。该计划的最终目标将是进行这样的建模，以便我们能够更准确地预测北方水生系统将如何应对气候变化。

Freshwater ice is an integral component of cold-regions lakes and rivers and an important modifier of related biological, chemical and physical processes.   Although serious concerns have been expressed about the impacts of climate change on ice-covered systems (e.g., the recent assessment by the Intergovernmental Panel on Climate Change and the Arctic Climate Impact Assessment), knowledge of such systems is relatively weak making it difficult to predict the nature of the effects of a changing climate.  This project will focus on filling some of our most important knowledge gaps by addressing three research areas: extreme hydrologic events; climatic controls; and effects on hydro-ecological systems.The focus of extreme hydrologic events will be river-ice breakup and associated ice jamming.  Such events can produce floods exceeding those possible under similar flow during the open-water period.  Although breakup flooding is known to produce significant economic damage and also to be critical to the environmental health of aquatic systems, no broad-scale assessment of its importance has been conducted.  This study will fill this gap by conducting a national and circumpolar evaluation of the historical frequency and magnitude of breakup floods and compare the results to those for the open-water period.  This will provide a basis for improved infrastructure planning and environmental management, as well as be the basis for the second objective of this research program: predicting how the frequency and magnitude of such extreme events will be affected by future climate change.   Major changes in river and lake ecology, particularly including the water quality, are also expected to result from climate-induced changes to river-ice cover.  Projected ecological changes, however, have been based primarily on guesstimates of changes in the ice cover, not on the results of physically-based models.  The final objective of this program will be to undertake such modelling so that we can more accurately forecast how northern aquatic systems will respond to climate change.