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世-普世热带陆地安第斯山脉温度放大演变
Lina C Pérez-Angel1,2, Julio Sepúlveda3,4, Peter Molnar3,5
1Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912.
概括
新纪的温暖,类似于今天的二氧化碳水平,使热带陆地温度明显高于新纪. 这项研究使用细菌脂质重建了过去的热带气温,揭示了气候变化动态的关键见解.
科学领域:
- 古气候学 古气候学
- 地质化学 地质化学
- 气候科学 气候科学
背景情况:
- 世时代经历了地球变暖,大气中的二氧化碳水平与今天 (>400 ppm) 相似.
- 过渡到较冷的普莱斯托时代标志着北半球冰川的开始.
- 尽管已知海洋温度变化,但在这个普略纪-普纪过渡期间热带陆地温度变化的定量数据是有限的.
研究的目的:
- 在热带地区重建Plio-Quaternary时期的定量陆地空气温度记录.
- 为了研究热带地区在普略纪-普纪过渡期间陆地温度变化的程度.
- 将热带陆地温度演变与海面温度 (SST) 进行比较,并评估温室气体强迫和区域反的影响.
主要方法:
- 利用了在哥伦比亚 (~4°N) 的Funza-II沉积物核心中保存的细菌分支甘油二甲基甘油四乙醇 (brGDGTs).
- 开发了一个精细的年龄模型,使用来自灰层的U-Pb石日期.
- 应用了一种新的混合源模型来区分湖泊和土壤衍生的brGDGTs,以准确估计温度.
主要成果:
- 新纪 (3.8至2.58万年) 的温度明显高于随后的新纪时期的温度 (°C).
- 重建的温度演变密切反映了长期的热带SST冷却.
- 北部热带安第斯地区的冷却幅度超过了理论预测,这表明区域反的作用.
结论:
- 热带陆地和海洋温度密切相关,受到温室气体强迫的影响.
- 区域因素,如过期率调整和太平洋SST梯度等,显著影响安第斯地区的温度变化.
- 了解过去的热带气温动态对于改进未来气候变暖预测至关重要.
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