Holocene climate variability in Texas, USA: An integration of existing paleoclimate data and modeling with a new, high-resolution speleothem record
Holocene climate variability in Texas, USA: An integration of existing paleoclimate data and modeling with a new, high-resolution speleothem record
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DOI：
10.1016/j.quascirev.2015.06.023
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发表时间：
2015-11
影响因子：
4
通讯作者：
Corinne I. Wong;J. Banner;M. Musgrove
中科院分区：
文献类型：
--
作者：
Corinne I. Wong;J. Banner;M. Musgrove
描述干旱易发的得克萨斯州的降水变异性的气候过程，预测和减轻气候变化的影响是至关重要的，需要重建过去的气候超出仪器记录。我们综合现有的古气候代理数据和气候模拟，提供了一个在德克萨斯州全新世气候变化的概述。从全新世早期到中期，气候逐渐变得温暖和干燥，在7到3 ka（千年前）之间达到顶峰，在全新世晚期变化更大。然而，由于不同记录之间存在相当大的变化，全新世气候变化的时间和相对幅度受到很大的限制。为了帮助解决这个问题，我们提出了一个新的洞穴（NBJ）重建从得克萨斯州中部的洞穴，包括最高分辨率的代理记录，到目前为止，跨越全新世中期至晚期。NBJ微量元素浓度表明可变的水分条件下，没有明确的时间趋势。NBJ生长速率、微量元素浓度和δ 18 O值之间存在解耦关系，这表明（i）洞穴沉积物生长速率和水分有效性之间通常存在的直接关系可能会因上覆生态系统的变化而变得复杂，这些变化影响地下CO2的产生，（ii）洞穴沉积物δ 18 O的变化可能反映了水分来源的变化（即，太平洋与墨西哥湾的水分比例），似乎与水分量无关。
Delineating the climate processes governing precipitation variability in drought-prone Texas is critical for predicting and mitigating climate change effects, and requires the reconstruction of past climate beyond the instrumental record. We synthesize existing paleoclimate proxy data and climate simulations to provide an overview of climate variability in Texas during the Holocene. Conditions became progressively warmer and drier transitioning from the early to mid Holocene, culminating between 7 and 3 ka (thousand years ago), and were more variable during the late Holocene. The timing and relative magnitude of Holocene climate variability, however, is poorly constrained owing to considerable variability among the different records. To help address this, we present a new speleothem (NBJ) reconstruction from a central Texas cave that comprises the highest resolution proxy record to date, spanning the mid to late Holocene. NBJ trace-element concentrations indicate variable moisture conditions with no clear temporal trend. There is a decoupling between NBJ growth rate, trace-element concentrations, and δ18O values, which indicate that (i) the often direct relation between speleothem growth rate and moisture availability is likely complicated by changes in the overlying ecosystem that affect subsurface CO2production, and (ii) speleothem δ18O variations likely reflect changes in moisture source (i.e., proportion of Pacific-vs. Gulf of Mexico-derived moisture) that appear not to be linked to moisture amount.