一个"雪球地球"气候由大陆的分裂引发,通过排水的变化
Yannick Donnadieu1, Yves Goddéris, Gilles Ramstein
1Laboratoire des Sciences du Climat et de l'Environnement, CNRS-CEA, 91191, Gif sur Yvette, France. tiphe@lsce.saclay.cea.fr
Nature
|March 19, 2004
概括
原生态时代的板块构造学和火山活动可能引发了大气层.
科学领域:
- 地质科学 地质科学
- 气候科学 气候科学
- 古气候学 古气候学
背景情况:
- 地质和古磁学的证据表明,全球冰盖在前生代晚期 (800-550亿年前) 达到赤道.
- 这种"雪球地球"假设需要大气中二氧化碳 (CO2) 水平明显低于今天,这种情况的原因仍在争论中.
- 较弱的太阳 (6%较暗) 也被认为是雪球地球情景的一个因素.
研究的目的:
- 调查史图尔特冰期 (7亿5千万年前) 之前的古地理变化在调节大气中的二氧化碳中的作用.
- 模拟大陆解体和火山活动对二氧化碳长期演变的影响.
主要方法:
- 使用了结合的气候地质化学模型GEOCLIM.
- 模拟了罗迪尼亚大陆分裂对流水,大陆气候变化和大气中二氧化碳度的影响.
- 纳入了与罗丁亚分裂相关的玄武岩流的气候影响.
主要成果:
- 模拟显示,罗丁亚的分裂增加了流水,导致大陆气候变化加剧,大气中的二氧化碳减少了每百万分之一的1,320个部分 (ppm).
- 增加的流水和玄武岩喷发的综合气候影响显著降低了二氧化碳水平.
- 这些二氧化碳的减少足以引发雪球冰化.
结论:
- 构造学变化,特别是罗丁亚的分裂,在新新生态时代,在地球从"温室"气候转变为"冰室"气候方面发挥了关键作用.
- 由火山活动放大的大陆气候变化是产生雪球地球所需的低二氧化碳条件的合理机制.
- 这项研究提供了构造过程和地球历史上极端气候事件之间的定量联系.
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