Abstract
This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) ~20–12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2–1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 °C) and moister climate with precipitation ×1.2–×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15–11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.
Highlights
At different time scales, from a few decades to tens of thousands of years, tropical glaciers are highly sensitive indicators of global climate change [1]
Following that criterion based on the Equilibrium Line Altitude (ELA) response to climate changes, two regions can be differentiated in the Central Andes [4,5]: northern and southern outer tropics, where the ELA is more sensitive to changes in temperature, and dry outer tropics (Arid Tropical Andes), where the ELA is more sensitive to changes in precipitation
Miocene volcanic slopes (
Summary
From a few decades to tens of thousands of years, tropical glaciers are highly sensitive indicators of global climate change [1]. This climatic sensitivity can be measured by estimating how the glacier Equilibrium Line Altitude (ELA; meters above sea level, hereafter m) varies with climate. The ELA sensitivity to changes in temperature and precipitation is strongly tied to the dominant ablation process, which in turn is determined by the pattern in accumulation [2,3]. Following that criterion based on the ELA response to climate changes, two regions can be differentiated in the Central Andes [4,5]: northern and southern outer tropics (humid Central Andes), where the ELA is more sensitive to changes in temperature, and dry outer tropics (Arid Tropical Andes), where the ELA is more sensitive to changes in precipitation
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