Large-scale temperature response to external forcing in simulations and reconstructions of the last millennium
Large-scale temperature response to external forcing in simulations and reconstructions of the last millennium
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DOI：
10.5194/cp-9-393-2013
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发表时间：
2013-01-01
影响因子：
4.3
通讯作者：
Zorita, E.
中科院分区：
文献类型：
--
作者：
Fernandez-Donado, L.;Gonzalez-Rouco, J. F.;Zorita, E.
了解自然气候变率及其驱动因素对评估未来气候变化至关重要。因此，将基于代理的气候重建与强迫因子进行比较，并将其与古气候模式模拟进行比较，对于深入了解内部变率与强迫变率的相对作用至关重要。本文回顾了在CMIP5-PMIP3（耦合模式比对项目第5阶段-古气候模拟比对项目第3阶段）协调工作之前近一千年的气候模拟状态，并与现有的温度重建结果进行了比较。模拟和重建在再现主要温度变化方面大致一致，并表明在多年代际或更长时间尺度上对外部强迫的总体线性响应。发现内部变率在半球和全球尺度上具有重要影响。从中世纪气候异常到小冰期过渡期间模拟温度变化的空间分布与重建结果不一致。因此，要么内部变率可能是形成千年温度变化的主要因素，要么模式模拟在实际反映对外部强迫的响应模式方面存在问题。最后一千年瞬态气候响应（LMTCR）的定义为分析模拟气候和重建气候之间的一致性提供了一个定量框架。除了模拟和重建的LMTCR范围之间的总体一致之外，该分析还能够挑出一些重建和模拟集合之间的具体差异。在重建显示与外部强迫的协变性降低或它们呈现高温度变化率的情况下，发现了分歧。
Understanding natural climate variability and its driving factors is crucial to assessing future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleo-climate model simulations is key to gaining insights into the relative roles of internal versus forced variability. A review of the state of modelling of the climate of the last millennium prior to the CMIP5-PMIP3 (Coupled Model Intercomparison Project Phase 5-Paleoclimate Modelling Intercomparison Project Phase 3) coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition from the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions. Thus, either internal variability is a possible major player in shaping temperature changes through the millennium or the model simulations have problems realistically representing the response pattern to external forcing. A last millennium transient climate response (LMTCR) is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed LMTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change.