Climate Extremes in a Warmer World: What the Pliocene tell us?

极端天气和气候伴随着不利的社会经济影响，引起公众和决策者的极大兴趣。这些事件的发生率已经加剧。北方野火的发生频率有所增加（例如，阿拉斯加和西伯利亚）。极端高温在东南亚和欧洲变得更加普遍，干旱在东非和南美洲变得更加普遍。该项目将通过对地球历史上温暖气候状态的研究，促进对水文和极端高温（如野火、热浪、干旱）的新视角。上新世中期暖期（~ 300万年前）是最后一次大气CO2与现在（~ 400ppm）相当。研究表明，上新世中期全球气温比前工业时代升高了5℃。北冰洋是季节性无冰的，北方森林一直延伸到北极海岸线，海平面比现在高几米。由于有丰富的地质证据和气候模型数据，上新世是国际古气候模型工作的重点。该项目将使用一系列数值气候模式来研究上新世中期的极端气候，这些模式在空间分辨率和复杂性上都有所不同。这些结果将与极端气候的观测趋势和不同温室气体排放/稳定情景下近期可能出现的极端气候的模拟结果进行比较。该项目有三个主要目标，利用历史观测为比较提供必要的基线：-分析上新世中期极端温度的地理分布、持续时间和频率，并将这些结果与未来的气候情景进行比较。-分析上新世中期水文极端事件（如干旱、强降雨事件）的地理分布、持续时间和频率，并将这些结果与未来气候情景进行比较。-阐明温度/水文极端事件与上新世野火的地理发生/可能性之间的关系。这将包括参考新的地质数据集，通过保存在多个陆地沉积物中的木炭层记录野火的发生。方法将现有的陆地上新世数据集与新的化石木炭赋存记录相结合。它将使用利兹大学生产的气候模型输出，并由国际上新世模式比对项目（PlioMIP）的成员提供，以调查高水平的颗粒气候数据（例如，每日月度数据的统计分析）。学生将研究来自一组高分辨率大气模式（HadAM3H 1.25 x 0.87）模拟的气候数据（3-hrly），以及一些世界上最新的气候和地球系统模式（例如，NCAR - CESM2和英国气象局- HadGEM3-AO）。

Weather and climate extremes, accompanied by adverse socio-economic impacts, are of great interest to the public and decision-makers. The prevalence of these events has intensified. Boreal wildfires have increased in frequency (e.g., Alaska and Siberia). Heat extremes have become more common in Southeast Asia and Europe, and droughts more common in East Africa and South America. This project will facilitate a novel perspective on hydrological and heat extremes (e.g., wildfire, heat waves, droughts) through the study of a warm climate state in Earth history. The mid-Pliocene Warm Period (~3 million years ago) was the last time atmospheric CO2 was comparable to present (~400 ppm). Studies indicate that the during the mid-Pliocene global temperatures were up to 5oC warmer than the pre-industrial era. The Arctic Ocean was seasonally ice-free, boreal forests reached the Arctic coastline and sea level was metres higher than it is today. Given a rich body of geological evidence, and climate model data the Pliocene is a key focus for international palaeoclimate modelling efforts.This project will investigate climate extremes during the mid-Pliocene using a spectrum of numerical climate models, that range in spatial resolution and complexity. These outcomes will be compared to both observational trends in climate extremes and simulations of plausible climate extremes of the near future under different greenhouse gas emission/stabilisation scenarios. The project has three main objectives using historical observations to provide the necessary baseline for comparison:- Analyse the geographical distribution, duration, and frequency of temperature extremes during the mid-Pliocene and compare these results to future climate scenarios. - Analyse the geographical distribution, duration, and frequency of hydrological extremes (e.g., droughts, high intensity rainfall events) during the mid-Pliocene and compare these results to future climate scenarios. - Elucidate the relationship between temperature/hydrological extremes and the geographical occurrence/likelihood of wildfires during the Pliocene. This will include reference to new geological data sets documenting wildfire occurrence through charcoal layers preserved in multiple terrestrial deposits. MethodsThe project will combine existing datasets of terrestrial Pliocene data with new records of fossil charcoal occurrence. It will use climate model outputs produced at Leeds and provided via members of the international Pliocene Model Intercomparison Project (PlioMIP), to investigate high-level granular climate data (e.g., statistical analysis of daily-monthly data). The student will examine climate data (3-hrly) from a set of high-resolution Atmosphere-only model (HadAM3H 1.25 x 0.87o) simulations as well as some of the worlds very latest climate and Earth System Model contributing to PlioMIP (e.g., NCAR - CESM2 & UK Met Office - HadGEM3-AO).