The response of the water cycle under elevated temperatures - lessons from the past

全球变暖被广泛认为是导致水循环加剧以及极端降雨事件的数量和规模增加的原因。然而，水循环的区域差异仍然是气候系统中最不被理解的方面之一。地球的历史包括过去的气候状态--“古气候”--为我们未来变暖的气候提供了经验教训，并有助于更好地理解地球系统。渐新世(约3400万至2300万年前)是一个以高温(比今天高出8摄氏度)为特征的古气候区间，可用于研究水循环在高温下的响应。然而，在这一关键的气候间隔期间，没有连续和直接的水文变化记录。叶蜡生物标志物的氢同位素组成是推断降雨量、水分来源和大气环流变化的有力工具(见下文)。在这个项目中，学生将：i)利用叶蜡生物标志物的氢同位素组成开发新的渐新世水文气候记录，ii)合成新的和现有的渐新世水文记录，以及iii)确定气候变暖时水文循环的响应。

Global warming is widely considered to cause intensification of the water cycle and an increase in the number and magnitude of extreme rainfall events. However, regional variations in the water cycle remain one of the worst understood aspects of the climate system. Earth's history includes past climate states-"paleoclimates"-that hold lessons for our future warm climate and have contributed towards an improved understanding of the Earth system. The Oligocene (~34 to 23 million years ago) is a paleoclimate interval characterised by high temperatures (> 8 Celsius higher than today) and can be used to study the response of the water cycle under elevated temperatures. However, there are no continuous and direct records of hydrological change during this key climate interval. The hydrogen isotopic composition of leaf wax biomarkers is a powerful tool used to infer changes in rainfall, moisture sources, and atmospheric circulation (see below). In this project, the student will: i) develop new hydroclimate records during the Oligocene using the hydrogen isotopic composition of leaf wax biomarkers, ii) synthesise new and existing hydrological records during the Oligocene, and iii) determine the response of the hydrological cycle in a warmer world.