北半球在最后一次除冰期期间强迫南半球气候
Feng He1, Jeremy D Shakun, Peter U Clark
1Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. fenghe@wisc.edu
Nature
|February 8, 2013
概括
关于冰川周期的米兰科维奇理论得到了支持,但南半球气候变化挑战了它. 我们的模型显示,轨道强迫启动了北半球脱冰,而大西洋南半球翻转循环变化解释了南半球变暖.
科学领域:
- 古气候学 古气候学
- 气候建模气候模型
- 地球系统科学 地球系统科学
背景情况:
- 米兰科维奇理论假设北半球夏季阳光照射通过冰盖质量平衡驱动冰川周期.
- 气候记录显示,南半球的气候变化与北半球的变化相应或导致,这挑战了理论.
- 在单独的信号处理中,很难区分半球对轨道强迫和独立强迫的反应.
研究的目的:
- 为了研究轨道变化,二氧化碳,冰盖和大西洋南部翻转循环 (AMOC) 对半球温度的影响.
- 为了确定在最后一次脱冰时期 (22-14年,3年) 脱冰的主要驱动因素.
- 为了协调半球半球气候变化在脱冰过程中的时间和领先/延迟.
主要方法:
- 使用合大气-海洋一般循环模型进行过渡模拟.
- 模拟包括来自轨道参数,大气CO2,冰盖和AMOC的强迫.
- 分析的重点是半球表面温度的演变和与除冰期的代理记录进行比较.
主要成果:
- 只有轨道变化的模拟支持了米兰科维奇理论,显示了北半球阳光和雪白度反引发的脱冰.
- 包括所有强迫因素在内的模拟最好地复制了南半球表面温度演变,包括时间和大小.
- 由轨道诱导的北半球冰盖退缩所驱动的AMOC变化是南半球早期变暖的最可能原因.
结论:
- 轨道强迫启动了北半球脱冰的过程.
- 大西洋南部翻转循环 (AMOC) 的变化可能解释了南半球的早期变暖及其对北半球的领先地位.
- 大气二氧化碳度上升为全球降冰提供了关键的积极反.
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