Testing the Tropical Greenhouse Forcing Hypothesis Using a Halmahera Proxy SST Record

使用哈马黑拉代理海表温度记录检验热带温室强迫假说

• 批准号: 0502609
• 负责人: David Lea
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-15 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502609&HistoricalAwards=false
• 关键词: Testing; Tropical; Greenhouse; Forcing; Hypothesis

Abstract: Under this award the proponents will test a new hypothesis: tropical ocean temperature variability over the last several hundred thousand years is dominantly driven by changes in greenhouse forcing. This hypothesis will be tested by developing a new proxy sea surface temperature (SST) record from a site in the western equatorial Pacific warm pool lying just east of Halmahera, Indonesia. A high sedimentation rate core (~15 cm/ky) from this site taken by collaborators from Tongji University in Shanghai, China will be targeted for development of a ~30-140 y resolution proxy SST record. SSTs will be reconstructed using the Mg content of the surface-dwelling planktonic foraminifera Globigerinoides rubber. The choice of proxy, resolutions and timescales will allow for three tests of the tropical greenhouse forcing hypothesis. In each case, the Halmahera SST record will be compared to the established greenhouse gas record to determine what fraction of the SST variance can be explained by greenhouse forcing, as opposed to other potential climate forcing mechanisms. The first test uses the near-monotonic rise and mid-rise plateau in atmospheric CO2 over the last deglaciation, the most well dated portion of both the ice core and marine records. The second test uses the four distinct oscillations in atmospheric CO2 that occurred between 65 and 20 thousand years before present during marine isotope stage (MIS) 3. The third test uses orbital scale (23- 100 ky) oscillations in atmospheric CO2 that are well documented in several Antarctic ice cores. Other climate influences will be evaluated as alternative hypotheses.The development of the Halmahera proxy SST record will add to available records of tropical Pacific climate variability on both centennial-to-millennial and orbital timescales. A high resolution (~30-70 y) record of warm pool SSTs during the deglaciation and MIS 3 has direct relevance to testing models of rapid climate change during these time intervals. In addition, if greenhouse forcing is the main control on tropical climate variability, the past relationship between forcing and temperature change provides a direct measure of climate sensitivity. Results from this study will advance independent determinations of climate sensitivity from paleoclimatic data. Broader impacts include collaboration with scientists in China and record of teaching and developing graduate students.

摘要：在这一奖项下，支持者将检验一个新的假设：过去几十万年热带海洋温度的变化主要是由温室效应的变化驱动的。这一假设将通过开发一个新的替代海表温度（SST）记录来验证，该记录来自位于印度尼西亚Halmahera以东的西赤道太平洋暖池。中国上海同济大学的研究人员将以该地点的高沉积速率岩心（~15 cm/ky）为目标，建立~30-140 y分辨率的代理海温记录。利用地表浮游有孔虫橡胶的Mg含量重建SSTs。代理、决议和时间尺度的选择将允许对热带温室强迫假说进行三次检验。在每种情况下，Halmahera海温记录将与现有的温室气体记录进行比较，以确定与其他潜在的气候强迫机制相反，温室强迫可以解释海温变化的哪个部分。第一个测试使用的是最后一次冰川消退期间大气中二氧化碳的近乎单调上升和中等上升的高原，这是冰芯和海洋记录中年代最准确的部分。第二个测试使用了在海洋同位素阶段（MIS） 3出现之前的6.5万年到2万年之间大气中二氧化碳的四种不同的振荡。第三个测试使用在几个南极冰芯中有充分记录的大气二氧化碳的轨道尺度（23- 100千克）振荡。其他气候影响将作为备选假设进行评估。Halmahera代理海温记录的发展将增加热带太平洋在百年至千年和轨道时间尺度上的气候变率的现有记录。在消冰期和MIS 3期间的高分辨率（~30-70 y）温池海温记录与这些时间间隔内快速气候变化的测试模式直接相关。此外，如果温室强迫是热带气候变率的主要控制因素，那么过去强迫与温度变化之间的关系提供了气候敏感性的直接度量。这项研究的结果将推动从古气候数据中独立确定气候敏感性。更广泛的影响包括与中国科学家的合作，以及教学和培养研究生的记录。