FUTURE-STORMS: Quantifying uncertainties and identifying drivers of future changes in weather extremes from convection-permitting model ensembles

气候变化可以说是本世纪人类面临的最大挑战，气候和水文极端事件的强度和频率的变化将对我们的社区产生重大影响。我们使用气候模型来预测未来的天气，这些计算机模型是基于基本的物理定律和复杂的数学方程，这必然会简化实际过程。其中一个真正重要的简化似乎是深层对流（想象一下导致雷暴的过程类型）。然而，现在计算机是如此强大，我们能够制作出在越来越小的尺度上工作的模型，最近我们开发了我们称之为“对流允许”的模型，我们不再使用这些对深对流的简化。这些“允许对流”的模式不一定能更好地模拟平均降雨量或降雨发生，但它们在模拟短时间内（少于一天）导致洪水，特别是山洪暴发事件的强降雨方面要好得多。它们也能更好地模拟我们观察到的随着气温上升而增加的强降雨；因此，我们对他们对未来强降雨变化的预测更有信心。一些“允许对流”的模拟实验现在已经在世界不同地区进行，但所有这些实验都是在小区域进行的，只有和英国一样大，或者更小。到目前为止，所有的实验都集中在降雨上，没有一个研究“允许对流”的模型如何改进对其他极端天气（如冰雹、闪电或风暴）的模拟。事实上，我们对这些极端气候在未来会如何变化知之甚少。就我们对未来变化的预测而言，我们也不知道我们的实验中的不确定性，因为我们只在每个地区运行了一个模式模拟——这对于规划气候适应策略没有用处，因为我们真正需要了解未来预测中的不确定性，以便我们能够为它们制定计划。在《未来风暴》中，我们在一个非常大的区域（整个欧洲）上运行这些“允许对流”的模型，我们比较了来自英国气象局和瑞士苏黎世联邦理工学院两个不同气候模型团队的模型。除此之外，我们现在能够在同一地区运行许多不同的气候模型，这使我们能够评估未来暴雨和其他与风暴相关的极端天气变化的一些不确定性。这将让我们探索整个欧洲的强降雨如何变化，以及可能导致这种变化的原因。这也将使我们看到这些新模型是否能够模拟其他类型的极端天气，如冰雹、闪电和风暴，这些天气对欧洲有巨大的影响，以及这些天气在未来会如何变化。最终，我们需要关于未来极端天气事件可能如何变化的更好信息，以便做出适应决策，而future - storms计划将提供这一重要进展，同时将这些信息转化为用于气候变化适应的有用工具和指标。

Climate change is arguably the biggest challenge facing people this century, and changes to the intensity and frequency of climatic and hydrologic extremes will have large impacts on our communities. We use climate models to tell us about what weather in the future will be like and these computer models are based on fundamental physical laws and complicated mathematical equations which necessarily simplify real processes. One of the simplifications that really seems to matter is that of deep convection (imagine the type of processes that cause a thunderstorm). However, computers are so powerful now that we are able to produce models that work on smaller and smaller scales, and recently we have developed models which we call "convection-permitting" where we stop using these simplifications of deep convection. These "convection-permitting" models are not necessarily better at simulating mean rainfall or rainfall occurrence but they are much better at simulating heavy rainfall over short time periods (less than one day) which cause flooding, in particular flash-flood events. They are also better at simulating the increase in heavy rainfall with temperature rise that we can observe; therefore we are more confident in their projections of changes in heavy rainfall for the future.A few "convection-permitting" modelling experiments have now been run for different parts of the world but all of these have been over small regions, only the same size as the UK, or smaller. All of the experiments so far have concentrated on rainfall and none have examined how "convection-permitting" models might improve the simulation of other types of extreme weather such as hail, lightning or windstorms. In fact we know very little about how these types of extremes might change in the future. We also have no idea of the uncertainty in our experiments in terms of our predictions of future changes as we have only run one model simulation in each region - this is not useful for planning climate adaptation strategies where we really need to understand the uncertainties in our future predictions so we can plan for them. In FUTURE-STORMS we are running these "convection-permitting" models over a very large area (the whole of Europe) and we are comparing models from two different climate modelling teams at the UK Met Office and ETH Zurich in Switzerland. In addition to this we are now able to run a number of different climate models over the same region, which allows us to assess some of the uncertainties in future changes to heavy rainfall and other storm-related extreme weather. This will let us explore how heavy rainfall might change across Europe and what might be causing this. It will also allow us to look at whether these new models are able to simulate other types of extreme weather like hail, lightning and windstorms which have a huge impact on Europe, and how these might change in the future. Ultimately, we need better information on how extreme weather events might change in the future on which to make adaptation decisions and FUTURE-STORMS intends to provide this important advance, alongside translating this information into useful tools and metrics for use in climate change adaptation.