High-latitude warming initiated the onset of the last deglaciation in the tropics.

Autor: Jackson MS; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA., Kelly MA; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA., Russell JM; Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912, USA., Doughty AM; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA.; Geology Department, Bates College, Lewiston, ME 04240, USA., Howley JA; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA., Chipman JW; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA., Cavagnaro D; Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA., Nakileza B; Mountain Resource Centre, Makerere University, Kampala, Uganda., Zimmerman SRH; Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
Jazyk: angličtina
Zdroj: Science advances [Sci Adv] 2019 Dec 11; Vol. 5 (12), pp. eaaw2610. Date of Electronic Publication: 2019 Dec 11 (Print Publication: 2019).
DOI: 10.1126/sciadv.aaw2610
Abstrakt: Atmospheric greenhouse gas concentrations are thought to have synchronized global temperatures during Pleistocene glacial-interglacial cycles, yet their impact relative to changes in high-latitude insolation and ice-sheet extent remains poorly constrained. Here, we use tropical glacial fluctuations to assess the timing of low-latitude temperature changes relative to global climate forcings. We report 10 Be ages of moraines in tropical East Africa and South America and show that glaciers reached their maxima at ~29 to 20 ka, during the global Last Glacial Maximum. Tropical glacial recession was underway by 20 ka, before the rapid CO 2 rise at ~18.2 ka. This "early" tropical warming was influenced by rising high-latitude insolation and coincident ice-sheet recession in both polar regions, which lowered the meridional thermal gradient and reduced tropical heat export to the high latitudes.
(Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).)
Databáze: MEDLINE
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