Resumen:
Our understanding of the climatic teleconnections that drove ice-age cycles has been
limited by a paucity of well-dated tropical records of glaciation that span several
glacial–interglacial intervals. Glacial deposits ofer discrete snapshots of glacier extent
but cannot provide the continuous records required for detailed interhemispheric
comparisons. By contrast, lakes located within glaciated catchments can provide
continuous archives of upstream glacial activity, but few such records extend beyond
the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon
basin provides the frst, to our knowledge, continuous, independently dated archive of
tropical glaciation spanning 700,000 years. We fnd that tropical glaciers tracked
changes in global ice volume and followed a clear approximately 100,000-year
periodicity. An enhancement in the extent of tropical Andean glaciers relative to global
ice volume occurred between 200,000 and 400,000 years ago, during sustained
intervals of regionally elevated hydrologic balance that modifed the regular
approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale
variations in the extent of tropical Andean glaciers during the last glacial cycle were
driven by variations in regional monsoon strength that were linked to temperature
perturbations in Greenland ice cores1
; these interhemispheric connections may have
existed during previous glacial cycles.
