The influence of proxy selection on global annual mean temperature reconstructions during the Common Era

IF 6 2区 地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY
Bao Yang, Xia Li, Minhui He, Feng Wang, Yesi Zhao, Peng Zhang, Jianglin Wang
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引用次数: 0

Abstract

The reconstruction of global annual mean temperatures made by the PAGES 2k Consortium in 2019 represents one of the most influential sequences of global climate variability over the Common Era. However, it is still not clear how the reconstruction can be influenced by the selection of reconstruction methods and the selection of proxy records with different temporal resolutions over different regions. We adopt a widely used Composite-Plus-Scale method to elucidate the effects of the selection of the proxy records on temperature reconstruction. To ensure the uniformity of data, different types of proxy records spanning the past ∼2000 years from the PAGES 2k proxy network were used to investigate the potential effects of proxy selection in hemispheric and global temperature reconstructions during the past two millennia. The long-term trends, spectral characteristics, and volcanic responses of the annual temperatures were studied based on the reconstructions. Our results reveal a significant cooling trend in the global annual mean temperature using both tree-ring and non-tree-ring records during the 1–1850 CE period, and show that the cooling exhibits a stronger trend in the Southern Hemisphere (SH) than that in the Northern Hemisphere (NH). Yet, the long-term trends vary according to different combinations of proxy records. Different reconstructions based on different types of proxies also exhibit different features in terms of volcanic responses and spectral properties. Tree-ring-based temperature reconstructions show stronger cooling responses to tropical volcanic eruptions, while non-tree-ring-based reconstructions suggest less robust volcanic responses, which may be related to dating uncertainties and low temporal resolution of the proxies. Tree-ring width records tend to preserve a substantial proportion of high-frequency (<200 years) variability, whereas non-tree-ring proxies tend to capture a larger fraction of low-frequency (>200 years) variations. Efforts are needed to reduce uncertainties of the temperature reconstruction over the Common Era associated with the insufficient spatiotemporal coverage of the current proxy network, especially for the first millennium and for the SH and tropics, also to develop statistical methods and to improve the signal strength and constrain uncertainties in existing proxy records.

公元纪代用指标选择对全球年平均气温重建的影响
PAGES 2k 联合会于 2019 年重建的全球年平均气温代表了公元纪全球气候变异性中最具影响力的序列之一。然而,重建方法的选择以及不同地区不同时间分辨率的代用记录的选择如何影响重建结果,目前仍不清楚。我们采用一种广泛使用的复合加尺度方法来阐明代用记录的选择对温度重建的影响。为了保证数据的统一性,我们使用了 PAGES 2k 代用网络中过去 2000 多年的不同类型的代用记录,研究了代用记录的选择对过去两千年半球和全球温度重建的潜在影响。根据重建结果研究了年气温的长期趋势、光谱特征和火山反应。我们的研究结果表明,在西元 1-1850 年期间,利用树环和非树环记录,全球年平均气温有明显的变冷趋势,而且南半球的变冷趋势比北半球更强。然而,长期趋势因代用记录的不同组合而异。基于不同类型代用资料的重建在火山响应和光谱特性方面也表现出不同的特征。基于树环的气温重建显示出热带火山爆发带来的更强的降温反应,而非基于树环的重建则显示出不太强烈的火山反应,这可能与年代的不确定性和代用指标的低时间分辨率有关。树环宽度记录往往保留了很大一部分高频率(200 年)变化,而非树环代用指标往往捕捉到较大一部分低频率(200 年)变化。需要努力减少与当前代用网络时空覆盖不足有关的公元纪温度重建的不确定性,特别是第一个千年以及SH和热带地区,还需要开发统计方法,提高信号强度,限制现有代用记录的不确定性。
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来源期刊
Science China Earth Sciences
Science China Earth Sciences GEOSCIENCES, MULTIDISCIPLINARY-
CiteScore
9.60
自引率
5.30%
发文量
135
审稿时长
3-8 weeks
期刊介绍: Science China Earth Sciences, an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China, and published by Science China Press, is committed to publishing high-quality, original results in both basic and applied research.
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