古气候模式效应有助于限制气候敏感性和21世纪的变暖
Vincent T Cooper1, Kyle C Armour1,2, Gregory J Hakim1
1Department of Atmospheric and Climate Science, University of Washington, Seattle, WA 98195.
概括
普略世等古气候为地球对温室气体的气候敏感性提供了信息. 考虑到过去的"模式效应",现代气候敏感度估计改为2.8°C,减少了未来变暖的不确定性.
科学领域:
- 古气候学 古气候学
- 气候建模 气候建模
- 地球系统科学 地球系统科学
背景情况:
- 古气候提供了对地球气候对温室气体排放的敏感性的见解.
- 新纪 (5.3-2.6万年前) 是现代变暖的关键类比,因为二氧化碳水平相似.
- 之前对世暖化和最后冰川最大期 (LGM) 降温的估计表明,气候敏感性比目前所接受的要高.
研究的目的:
- 调查古气候温度模式如何影响气候敏感度估计.
- 在推断气候敏感性时,要考虑由过去和现在气候状态之间的差异产生的"模式效应".
- 通过结合古气候数据和建模来完善现代地球气候敏感性的估计.
主要方法:
- 结合数据同化重建与大气一般循环模型.
- 分析了普略纪和LGM气候重建,考虑了诸如冰盖,地形和植被等因素.
- 量化了古气候"模式效应"对气候反和敏感性的影响.
主要成果:
- 与现代的二氧化碳强迫相比,地球的气候对普略纪强迫的敏感性更高.
- 纪的冰盖,地形和植被改变了海洋变暖模式,并放大了云反.
- 同样地,北美冰盖也放大了LGM反.
结论:
- 考虑到古气候"模式效应"对于准确的气候敏感性评估至关重要.
- 现代气候敏感度的精细最佳估计为2.8°C (66% CI:2.43.4°C).
- 这项研究大大减少了21世纪全球变暖预测中的不确定性.
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