Last Glacial Maximum Reconstructions of Rwenzori Mountain Glaciers
Last Glacial Maximum Reconstructions of Rwenzori Mountain Glaciers
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DOI：
10.1029/2022pa004527
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发表时间：
2023-01
影响因子：
3.5
通讯作者：
A. Doughty;M. Kelly;J. Russell;M. Jackson;Brian M. Anderson;J. Chipman;B. Nakileza
中科院分区：
文献类型：
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作者：
A. Doughty;M. Kelly;J. Russell;M. Jackson;Brian M. Anderson;J. Chipman;B. Nakileza
末次盛冰期（LGM; 19-26.5 ka）期间热带冷却的幅度仍然存在争议，海面温度比高海拔地区重建的大多数温度低几度。为了解释这种差异，过去的研究提出了一个陡峭的（增加）直减率-温度下降与海拔-在LGM相对于今天。例如，东非的末次盛冰期温度是从多个海拔的分支GDGT重建的，这支持了末次盛冰期相对于现在的直减率增加了0.9°C/km。递减率是地球气候敏感性和大气能量转移的关键部分，了解LGM期间热带递减率是否变陡以及变陡了多少至关重要。在这里，我们模拟末次冰期冰川范围内的乌干达鲁文佐里山脉，并没有使用一系列的温度和降水量的估计在递减率的变化。我们发现，使用东非现有的海平面温度和降水估计，冰川到达LGM位置的直减率必须比现在更陡。
The magnitude of tropical cooling during the Last Glacial Maximum (LGM; ∼19–26.5 ka) remains controversial, with sea‐surface temperatures cooling by several degrees less than most temperatures reconstructed at high elevations. To explain this discrepancy, past studies proposed a steeper (increased) lapse rate—the temperature decrease with elevation—during the LGM relative to today. For instance, LGM temperatures in East Africa reconstructed from branched GDGTs from multiple elevations support an ∼0.9°C/km increase in the lapse rate during the LGM relative to present day. Lapse rates are a critical part of the Earth's climate sensitivity and atmospheric energy transfer, and it is vital to know whether and by how much the tropical lapse rate steepened during the LGM. Here, we simulate LGM glacier extents in the Rwenzori Mountains of Uganda with and without a change in lapse rate using a range of temperature and precipitation estimates. We find that the lapse rate must have been steeper than present for glaciers to reach their LGM positions using available sea‐level temperature and precipitation estimates for East Africa.