Global Synthesis of Regional Holocene Hydroclimate Variability Using Proxy and Model Data
Global Synthesis of Regional Holocene Hydroclimate Variability Using Proxy and Model Data
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DOI：
10.1029/2022pa004597
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发表时间：
2023-05
影响因子：
3.5
通讯作者：
Chris Hancock;N. McKay;M. Erb;D. Kaufman;Cody R. Routson;R. Ivanović;L. Gregoire;P. Valdes
中科院分区：
文献类型：
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作者：
Chris Hancock;N. McKay;M. Erb;D. Kaufman;Cody R. Routson;R. Ivanović;L. Gregoire;P. Valdes
全新世期间陆地水文气候的实质性变化被记录在地质档案中，并由计算机模型模拟。为了确定过去12ka的时空模式，从全球(n=813)收集了对降水和有效湿度(降水量减去蒸发量)变化敏感的替代记录。计算了IPCC AR6的30个区域的代理复合时间序列，并与两个全全新世瞬变模型模拟(TRACE-21ka和HadCM3)和12个中全新世CMIP6模拟进行了比较。我们发现，在整个北半球季风区，代理和模式模拟表明，在全新世早期和中期，比现代更潮湿的条件，而南半球季风区更干燥。这种日照驱动的近代值趋势始于大约6000年前，代理记录和模型之间的明显一致可能反映了这些地区降水变化的巨大幅度和一致的大气环流强迫机制。在中纬度地区，变化的模式不那么确定。总体而言，代理人复合体在整个全新世中纬度北部地区显示出湿润的趋势，这可能是由于纬度温度梯度的增加加强了西风带。然而，模拟表明，变化的幅度相对较低，对于北美的部分地区，存在代理模型的分歧。在高纬度地区，水文气候与温度呈正相关，无论是在代理中还是在模型中，都与随着温度上升而预测的湿润相一致。总体而言，这个大型替代数据库揭示了水气候变异性的一致模式，尽管与重建水气候场相关的挑战。
Substantial changes in terrestrial hydroclimate during the Holocene are recorded in geological archives and simulated by computer models. To identify spatial and temporal patterns during the past 12 ka, proxy records sensitive to changing precipitation and effective moisture (precipitation minus evaporation) were compiled from across the globe (n = 813). Proxy composite timeseries were computed for 30 of the IPCC AR6 regions and compared to two full‐Holocene transient model simulations (TraCE‐21ka and HadCM3) and twelve mid‐Holocene CMIP6 simulations. We find that throughout Northern Hemisphere monsoon regions, proxy and model simulations indicate wetter‐than‐modern conditions during the early and mid‐Holocene while Southern Hemisphere monsoon regions were drier. This insolation driven trend toward modern values began approximately 6,000 years ago, and the clear agreement among proxy records and models may reflect the large magnitude of precipitation change and consistent atmospheric circulation forcing mechanism for these regions. In the midlatitudes, the pattern of change is less certain. Generally, proxy composites show a wetting trend throughout the Holocene for the northern midlatitudes, possibly due to strengthening westerlies from an increasing latitudinal temperature gradient. However, simulations indicate that the magnitude of change was relatively low, and for portions of North America, there is a proxy‐model disagreement. At high latitudes, hydroclimate is positively correlated with temperature in both proxies and models, consistent with projected wetting as temperatures rise. Overall, this large proxy database reveals a coherent pattern of hydroclimate variability despite the challenges associated with reconstructing hydroclimate fields.