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

• Published in: Science Advances
• Main Authors: Jackson, Margaret S, Kelly, Meredith A., Russell, James M., Doughty, Alice M., Howley, Jennifer A., Chipman, Jonathan W., Cavagnaro, David, Nakileza, Bob, Zimmerman, Susan R.H.
• Format: Text
• Language: unknown
• Published: Dartmouth Digital Commons 2019
• Subjects: Ice Sheet
• Online Access: https://digitalcommons.dartmouth.edu/facoa/4083; https://doi.org/10.1126/sciadv.aaw2610; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6905867/

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 10Be 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 CO2 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.