晚期米奥森大气中的CO2度和C2草的扩张
1Department of Geosciences, The Pennsylvania State University, University Park, PA 16872, USA.
概括
大气中的二氧化碳 (CO2) 在米奥森末期并没有减少,这与之前的理论相反. 相反,C4草原的扩张很可能是由干旱和降雨模式的变化所驱动的.
科学领域:
- 古气候学 古气候学
- 古植物学是古植物学.
- 地质化学 地质化学
背景情况:
- 在中新世纪晚期C4草原的扩张以前被认为是大气二氧化碳 (CO2) 水平的下降.
- 由于缺乏对二氧化碳变化的直接证据以及其他环境因素对植物分布的已知影响,这一假设仍在争论中.
研究的目的:
- 研究大气二氧化碳 (pCO2) 部分压力在推动中新纪C4晚期草原扩张中的作用.
- 为了提供pCO2在中新世纪晚期波动的直接证据.
主要方法:
- 利用基于基的地化学代理来重建过去的大气pCO2水平.
- 分析了沉积物核心,以建立pCO2变化的时间表,从1400万年前到900万年前.
主要成果:
- 基于基的pCO2估计显示,从1400万年前增加到900万年前,然后稳定在工业化前的水平.
- 没有发现有意义的证据表明pCO2在中新世纪晚期大幅下降.
结论:
- C4草原的米奥森晚期扩张并不是由于大气CO2的减少而导致的.
- 其他因素,如干旱程度增加或降水模式改变,可能起到了更重要的作用.
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