GLOBAL-EX: A GLOBAL theory for EXtreme land temperatures in a changing climate

随着气候变暖，极端高温的频率和强度都在增加。极端高温的影响广泛而严重，到本世纪末，世界部分地区可能变得不适合居住。然而，极端温度的未来是高度不确定的：气候模型预测的反应范围很广，因此很难为极端高温的不断升级的影响做好准备。这种巨大的不确定性由于缺乏关于气候变化中极端温度的全球理论而变得更加复杂，这对我们理解具有重要社会影响的气候系统构成了根本性挑战。GLOBAL-EX将结合模拟，观测分析和物理理论的层次结构，以改变极端温度科学的最新状态。总体目标是为气候变化下的陆地极端温度建立一个全球理论。实现这一目标需要两个步骤：首先，我将在大范围的气候状态下进行理想化的模拟，以确定大气动力学对极端温度事件施加的大规模约束。其次，我将使用新颖的区域模拟结合观测数据分析来分解控制炎热天气土地湿度的过程，这些过程与极端温度密切相关。新理论将用于量化近几十年来极端温度趋势的驱动因素，并了解极端高温对未来温室气体浓度变化的响应行为。该项目不仅为我们对气候系统的基本理解迈出了重要一步，还有望为缩小极端温度预测中的巨大不确定性找到新的途径，为全世界的脆弱社会带来好处。

Extreme hot temperatures are increasing in frequency and intensity as climate warms. The impacts of extreme heat are widespread and severe, with parts of the world potentially becoming uninhabitable by the end of this century. Yet the future of extreme temperatures is highly uncertain: Climate models project a wide range of responses, making it difficult to prepare for the escalating effects of extreme heat. This large uncertainty is compounded by the lack of a global theory for extreme temperatures in a changing climate, representing a fundamental challenge to our understanding of the climate system with critical societal impacts.GLOBAL-EX will combine a hierarchy of simulations, observational analyses and physical theory to transform the state of the art in the science of extreme temperatures. The overarching goal is to build a global theory for extreme temperatures over land in a changing climate. Two steps are required to achieve this goal: First, I will perform idealised simulations spanning a wide range of climate states to identify the large-scale constraints imposed by atmospheric dynamics on extreme-temperature events. Second, I will use novel regional simulations together with analyses of observational data to decompose the processes controlling land humidity on hot days, which are tightly coupled to extreme temperatures. The new theory will be applied to quantify the drivers of trends in extreme temperatures over recent decades and to understand the behaviour of extreme heat in response to future changes in greenhouse gas concentrations. Not only will this project provide a major step forward in our fundamental understanding of the climate system, GLOBAL-EX is also expected to identify new pathways to narrowing large uncertainties in projections of extreme temperatures, with benefits for vulnerable societies throughout the world.