Collaborative Research: Testing Mechanisms of Tropical Climate Change and Variability Using New Cores from the Line Islands

热带太平洋的海气耦合相互作用是现代全球年际气候变率的主要来源。 这种变异性被称为厄尔尼诺-南方涛动（ENSO），远远超出了热带太平洋，影响到全球气候和人口。 因此，了解气候变化如何改变这些相互作用，对于人类社会减缓和适应未来的变化至关重要。发现是外部强迫还是内部变率决定了ENSO行为，将大大加深我们对ENSO的理论理解，提高我们在气候变化下准确预测ENSO行为的能力。除了这些广泛的科学和社会效益，该项目将为研究生和本科生提供研究机会。该项目还为开发K-12教学单元提供了一个平台，将与公立学校教师以及圣克鲁斯的加州大学培训的本科科学教师合作设计这些教学单元。000年来测试改变热带气候和厄尔尼诺-南方涛动（ENSO）行为的因素。ENSO是全球气候年际变率的主要原因，但它的行为如何改变未来的气候变化还不清楚。 了解过去全球气温不同时ENSO行为的变化将是这方面的一个重大进展。 ENSO的行为是重建从海洋表面温度的变化所确定的化石有孔虫壳的化学在深海沉积物附近的莱恩群岛，在太平洋中部。 每个个体浮游有孔虫壳的Mg/Ca比和氧同位素组成记录了一个月的海面温度快照。 对单个沉积层中许多单个贝壳的测量记录了海洋表面温度随沉积时间的变化。 由于ENSO是莱恩群岛附近海面温度变率的主要原因，过去温度变率的变化显示了ENSO行为在过去的变化。 这些数据将检验赤道太平洋对地球轨道太阳日射量变化以及对全球气温和温室气体（pCO 2）强迫的冰川-间冰期变化的动态反应，从而增进我们对厄尔尼诺/南方涛动现象及其今后可能如何变化的了解。

Coupled ocean-atmosphere interactions in the tropical Pacific are the leading source of modern global interannual climate variability. This variability, expressed as the El Niño-Southern Oscillation (ENSO), extends far beyond the tropical Pacific, affecting climate and human populations globally. Understanding how climate change alters these interactions is therefore critical for human societies to mitigate and adapt to future change. Discovering whether external forcing or internal variability determines ENSO behavior will greatly deepen our theoretical understanding of ENSO and improve our ability to accurately forecast ENSO behavior under altered climates. In addition to these broad scientific and societal benefits, this project will provide research opportunities for graduate and undergraduate students. The project also provides a platform for the development of K-12 teaching modules, which will be designed in collaboration with public school teachers as well as an undergraduate science teacher in training at the University of California, Santa Cruz.This project is developing records of equatorial Pacific Ocean sea-surface temperature variability during the past 250,000 years to test factors that alter tropical climate and the behavior of the El Niño-Southern Oscillation (ENSO). ENSO is the dominant cause of interannual climate variability globally, yet it is not known how its behavior could change with future climate change. Understanding past changes in the behavior of ENSO, when global temperatures were different, will be a significant advance in this regard. ENSO behavior is reconstructed from the variability of sea-surface temperatures determined by the chemistry of fossil foraminifera shells in deep-sea sediments near the Line Islands, in the central Pacific. The Mg/Ca ratio and oxygen isotope composition of each individual planktonic foraminifera shell records a one-month snapshot of sea-surface temperature. Measurement of many individual shells from a single sediment layer documents the variability of sea surface temperatures over the time of deposition. Because ENSO is the primary cause of sea-surface temperature variability near the Line Islands, past changes in temperature variability show how ENSO behavior changed in the past. These data will test the dynamic response of the equatorial Pacific to changes in solar insolation from Earth's orbit, and to glacial-interglacial changes in global temperature and greenhouse gas (pCO2) forcing, improving our understanding of the ENSO phenomenon and how it might change in the future.