Reconstructing Holocene temperatures in time and space using paleoclimate data assimilation
Reconstructing Holocene temperatures in time and space using paleoclimate data assimilation
复制标题
DOI：
10.5194/cp-18-2599-2022
复制
发表时间：
2022-12
影响因子：
4.3
通讯作者：
M. Erb;N. McKay;N. Steiger;S. Dee;Chris Hancock;R. Ivanović;L. Gregoire;P. Valdes
中科院分区：
文献类型：
--
作者：
M. Erb;N. McKay;N. Steiger;S. Dee;Chris Hancock;R. Ivanović;L. Gregoire;P. Valdes
抽象的。古气候记录提供了有关全新世气候的宝贵信息，揭示了世界各地众多地点的气候变化的各个方面。然而，此类数据也存在局限性。代理网络在空间上不均匀、季节性有偏差、时间上不确定，并且在协同使用来说明过去气候的复杂变化时会带来各种挑战。古气候数据同化提供了一种重建过去气候的方法，可以解释代理记录的多样性，同时保持气候模型模拟的基于物理的协方差结构。在这里，我们使用来自Temperature 12k数据库的代理数据和瞬态气候模型模拟的输出，利用古气候数据同化来创建过去12000年温度的空间完整重建。在最后一个冰期之后，重建显示全新世气温在近 6400 年前升温至峰值，随后缓慢冷却直至今日，支持全新世中期至少与工业化前一样温暖。敏感性测试表明，如果代理忽略了夏季偏差，一些明显的全新世中期温暖实际上可能代表夏季趋势，而不是年平均趋势。无论如何，代理季节性偏差的潜在影响不足以使重建的全球平均温度与瞬态模型模拟中看到的变暖趋势保持一致。
Abstract. Paleoclimatic records provide valuable information about Holocene climate, revealing aspects of climate variability for a multitude of sites around the world. However, such data also possess limitations. Proxy networks are spatially uneven, seasonally biased, uncertain in time, and present a variety of challenges when used in concert to illustrate the complex variations of past climate. Paleoclimatic data assimilation provides one approach to reconstructing past climate that can account for the diverse nature of proxy records while maintaining the physics-based covariance structures simulated by climate models. Here, we use paleoclimate data assimilation to create a spatially complete reconstruction of temperature over the past 12 000 years using proxy data from the Temperature 12k database and output from transient climate model simulations. Following the last glacial period, the reconstruction shows Holocene temperatures warming to a peak near 6400 years ago followed by a slow cooling toward the present day, supporting a mid-Holocene which is at least as warm as the preindustrial. Sensitivity tests show that if proxies have an overlooked summer bias, some apparent mid-Holocene warmth could actually represent summer trends rather than annual mean trends. Regardless, the potential effects of proxy seasonal biases are insufficient to align the reconstructed global mean temperature with the warming trends seen in transient model simulations.