Paleoclimate data constraints on climate sensitivity: The paleocalibration method
Paleoclimate data constraints on climate sensitivity: The paleocalibration method
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古气候数据对气候敏感性的限制：古校准方法
DOI：
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发表时间：
1996
期刊：
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通讯作者：
M. Hoffert
中科院分区：
文献类型：
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作者：
C. Covey;L. Sloan;M. Hoffert
古气候和未来气候之间的关系，虽然不像Budyko和其他人的“古气候模拟”研究中所暗示的那样简单，但提供了足够的限制，以广泛地确认理论模型的气候敏感性范围，并可能最终缩小模型衍生的不确定性。我们使用一种名为“古校准”的新技术来计算地球历史三个关键间隔内全球平均尺度上温度响应与强迫的比率。通过研究从末次盛冰期、白垩纪中期和始新世早期的地质数据重建的地表条件，我们可以估计不同极端气候的平衡气候对辐射强迫变化的敏感性。我们发现，这三个时期的比率，在误差范围内，都在于从大气环流模型获得的范围：2-5 K全球变暖的大气二氧化碳的两倍。因此，古校准为理论计算的气候敏感性提供了基于数据的确认。然而，当与区域尺度上的古数据相比，模型显示与数据不太一致。例如，我们对始新世早期的GCM模拟未能获得数据所指示的赤道和两极之间（以及陆地和海洋区域之间）的温度对比，即使它与全球平均温度数据一致。其他人也报道了白垩纪和末次冰盛期的类似结果。
The relationship between paleoclimates and the future climate, while not as simple as implied in the ‘paleoanalog’ studies of Budyko and others, nevertheless provides sufficient constraints to broadly confirm the climate sensitivity range of theoretical models and perhaps eventually narrow the model-derived uncertainties. We use a new technique called ‘paleocalibration’ to calculate the ratio of temperature response to forcing on a global mean scale for three key intervals of Earth history. By examining surface conditions reconstructed from geologic data for the Last Glacial Maximum, the middle Cretaceous and the early Eocene, we can estimate the equilibrium climate sensitivity to radiative forcing changes for different extreme climates. We find that the ratios for these three periods, within error bounds, all lie in the range obtained from general circulation models: 2–5 K global warming for doubled atmospheric carbon dioxide. Paleocalibration thus provides a data-based confirmation of theoretically calculated climate sensitivity. However, when compared with paleodata on regional scales, the models show less agreeement with data. For example, our GCM simulation of the early Eocene fails to obtain the temperature contrasts between the Equator and the Poles (and between land and ocean areas) indicated by the data, even though it agrees with the temperature data in the global average. Similar results have been reported by others for the Cretaceous and for the Last Glacial Maximum.