Regional climate risks from compound effects and their previsibility under climate change

地球的气候系统即将发生重大变化。根据政府间气候变化专门委员会的最新评估报告，到本世纪末，在北极变暖的强烈放大的背景下，加拿大将经历世界上最强烈的变暖之一。这可能不仅会改变气象灾害和极端天气，而且还会改变（所有类型）降水的持续时间、强度和发生情况，以及风和温度的状况，特别是在变暖最为明显的地区。根据未来的变暖阈值，评估结合多变量气候变量的高影响天气条件变得越来越重要，因为这些气候条件往往比单独考虑的变量变化所产生的风险更高，往往具有更强的稳健性或高概率。此外，基于单变量统计的评估可能会严重低估与特定极端事件相关的风险，特别是如果这些影响是由几个因变量或温和天气条件共同造成的，并在区域或地方尺度上产生极端影响。这就是为什么需要对同时发生的极端事件或气象灾害的复合影响进行预先预测，其中包括更好地理解和识别精细尺度上的关键物理过程，以减少它们的负面影响并更好地预防这些事件。目前缺乏对区域或地方尺度的强劲气候风险水平的评估，主要是因为目前加拿大气候变化研究中使用的粗尺度气候模式没有很好地解决导致其发生的物理过程。这就需要使用非常高分辨率的天气和气候模式（例如，使用“允许对流”模式），以综合考虑局部因素（例如，地形、地表条件、环境特征等）和大规模影响。此外，水文气象风险的预见性和评估无疑需要根据其影响提供有针对性的信息。该发现基金（DG）项目将结合中等分辨率（例如11公里）和非常高分辨率（例如允许对流< 3公里）的区域气候模式模拟，以识别和评估复合效应造成的大气危害和高影响天气条件的严重程度、持续时间和发生情况。这将有助于开发基于物理和定向影响方法的早期预警系统，并更好地准备和减少气候变化下一系列不利天气和气候条件的后果。这项DG研究还将有助于帮助利益相关者和政府组织加强组织、社区和个人的复原力，同时考虑到大气危害中最可能发生的变化。

Our planet's climate system is on the margin of a major shift. According to the last Intergovernmental Panel on Climate Change assessment report, Canada will experience one of the strongest warmings in the world by the end of this century, in the context of a strong arctic amplification of warming. This is likely not only to modify the meteorological hazards and extremes, but also the duration, intensity and occurrence of precipitation (of all types), and the regime of winds and temperatures, especially in areas where warming will be most marked. Depending on future warming thresholds, it becomes increasingly crucial to assess the high-impact weather conditions that combine multivariate climate variables, because these are often associated with a higher risk, often with greater robustness or high probability, than those resulting from changes in the variables considered in isolation. In addition, assessments based on univariate statistics can significantly underestimate the risks associated with given extremes, especially if the impacts are the result of several dependent variables or moderate weather conditions that combine and generate extreme impacts at the regional or local scale. That's why, the previsibility of compound effects from concurrent extremes or meteorological hazards is needed, that include a better understanding and identification of key physical processes at fine scales, in order to reduce their negative impacts and to better prevent those events. The assessment of robust climate risk levels at the regional or local scale is currently lacking, mainly because the physical processes responsible for their occurrence are not well resolved in coarse scale climate models currently used in Canadian climate change research. This requires the use of very high-resolution weather and climate models (e.g., using "convection-permitting" models) to take into account the combination of local factors (e.g., topography, surface conditions, environmental features, etc.) and large-scale influences. In addition, the previsibility and assessment of hydrometeorological risks undoubtedly needs to be improved with oriented information based on their impacts. This Discovery Grant (DG) program will combine both regional climate model simulations at intermediate resolution (ex. 11 km) and very high resolution (e.g., convection-permitting < 3 km) to identify and evaluate the severity, duration and occurrence of atmospheric hazards and high impact weather conditions from compound effects. This will help to develop early warning systems with physically based and oriented impact approaches, and to be better prepare and to reduce consequences from a range of adverse weather and climate conditions under climate change. This DG research will also contribute to help stakeholders and governmental organizations to reinforce the resilience of organization, communities and individuals, considering the most plausible changes in atmospheric hazards.