A brGDGT‐Based Reconstruction of Terrestrial Temperature From the Maritime Continent Spanning the Last Glacial Maximum
A brGDGT‐Based Reconstruction of Terrestrial Temperature From the Maritime Continent Spanning the Last Glacial Maximum
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DOI：
10.1029/2022pa004501
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发表时间：
2023-02
影响因子：
3.5
通讯作者：
M. Parish;X. Du;S. Bijaksana;J. Russell
中科院分区：
文献类型：
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作者：
M. Parish;X. Du;S. Bijaksana;J. Russell
热带地区对全球气候有着巨大的影响。尽管热带地区具有重要意义，但印度洋-太平洋暖池（IPWP）地区在末次冰消期的陆地温度史却知之甚少。尽管大量的海表温度（SST）重建提供了从末次盛冰期到全新世海表温度变暖的估计，但不同记录之间冰化变暖开始的时间不同，并且抑制了IPWP中驱动冰化变暖的强迫的确定。我们基于位于印度尼西亚苏拉威西的托乌提湖沉积物岩心中的支链甘油二烷基甘油四醚（brGDGTs）进行了60,000年的温度重建。BrGDGTs是细菌跨膜脂质，在全球范围内，随着温度的降低甲基化程度越来越高，随着ph的降低环化程度越来越高。尽管在区域和全球校准中，温度的变化是BrGDGTs的主要控制因素，但我们发现BrGDGTs的环化是图乌提湖生物地球化学环境的重要变化的主要变化模式。我们将湖泊化学变化和温度变化对brGDGT记录的影响分离出来，建立了一个跨越6万年的温度记录。在我们的记录中，去冰变暖的时间发生在CO2浓度开始增加之后，这表明温室气体浓度的上升和相关的辐射强迫可能迫使IPWP的去冰变暖。55和34 ka前后的温度峰值表明，北半球夏季日照也可能影响IPWP区域的地表温度。
The tropics exert enormous influence on global climate. Despite the importance of tropical regions, the terrestrial temperature history in the Indo‐Pacific Warm Pool (IPWP) region during the last deglaciation is poorly constrained. Although numerous sea surface temperature (SST) reconstructions provide estimates of SST warming from the Last Glacial Maximum to the Holocene, the timing of the onset of deglacial warming varies between records and inhibits determining the forcings driving deglacial warming in the IPWP. We present a 60,000‐year long temperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) in a sediment core from Lake Towuti, located in Sulawesi, Indonesia. BrGDGTs are bacterial membrane‐spanning lipids that, globally, become more methylated with decreasing temperature and more cyclized with decreasing pH. Although changes in temperature are the dominant control on brGDGTs in regional and global calibrations, we find that the cyclization of the brGDGTs is a major mode of variation at Lake Towuti that records important changes in the lacustrine biogeochemical environment. We separate the influence of lake chemistry changes from temperature changes on the brGDGT records, and develop a temperature record spanning the last 60,000 years. The timing of the deglacial warming in our record occurs after the onset of the deglacial increase in CO2 concentrations, which suggests rising greenhouse gas concentrations and the associated radiative forcing may have forced deglacial warming in the IPWP. Peaks in temperature around 55 and 34 ka indicate that Northern Hemisphere summer insolation may also influence land surface temperature in the IPWP region.