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，极端气候和水文的强度和频率的变化将对我们的社区产生巨大影响。我们使用气候模型来告诉我们未来的天气会是什么样的，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，这些数学方程必然会简化真实的过程。其中一个似乎真正重要的简化是深对流（想象一下导致雷暴的过程类型）。然而，现在的计算机是如此强大，我们能够产生在越来越小的尺度上工作的模型，最近我们已经开发了我们称之为“对流允许”的模型，在那里我们不再使用这些对深对流的简化。这些“允许对流”的模式不一定更好地模拟平均降雨量或降雨发生，但它们更好地模拟短时间内（不到一天）的暴雨，造成洪水，特别是山洪事件。他们也更擅长模拟我们可以观察到的随着温度升高而增加的暴雨;因此我们对他们预测未来暴雨变化更有信心。一些“允许对流”的模拟实验现在已经在世界不同地区进行，但所有这些都是在小区域进行的，只有与英国相同的大小，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”的模型如何改善对冰雹、闪电或风暴等其他类型极端天气的模拟。事实上，我们对这些类型的极端在未来会如何变化知之甚少。我们也不知道我们的实验在预测未来变化方面的不确定性，因为我们只在每个地区运行了一个模型模拟-这对规划气候适应战略没有用处，因为我们真的需要了解我们未来预测中的不确定性，以便我们可以为它们做计划。在未来风暴中，我们在一个非常大的区域（整个欧洲）运行这些“允许对流”的模型，我们正在比较来自英国气象局和瑞士苏黎世ETH的两个不同气候模型团队的模型。除此之外，我们现在还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强降雨和其他与风暴相关的极端天气变化的一些不确定性。这将让我们探索欧洲各地的强降雨可能会如何变化，以及可能导致这种变化的原因。它还将使我们能够了解这些新模型是否能够模拟对欧洲产生巨大影响的其他类型的极端天气，如冰雹，闪电和风暴，以及这些天气在未来可能如何变化。最终，我们需要更好的信息来了解极端天气事件在未来可能如何变化，以便做出适应性决策，而FUTURE-STORMS旨在提供这一重要进展，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.