Mid- and Late-Holocene Climate Variability of the Central Andes (Peru and Bolivia) Reviewed from δ18O Stratigraphy of Ice Cores

Glacial ice cores are evidence of past environmental conditions through gases and particulate matter trapped within the drilled material. The Central Andes in the South American region are highly sensitive to climate changes; a long record of temperature and precipitation variability can be found in relation to massive ice caps. Available oxygen isotope data from three glacial ice cores from Nevados Sajama, Huascaran and Illimani (Peru and Bolivia) drilled over the last decades in the Central Andes are revisited to investigate climate variability over the past seven millennia, a period characterized globally by remarkable climatic stability. The analysis revealed statistically significant millennial- and centennial-scale periodicities in the isotope records ranging from centennial to millennial timescales. These cycles have periods of 1.3, 0.87, 0.67, 0.46, and 0.25 kiloyears (ka). A series of regional temperature minima and maxima are also identified. This variability in the Andean climate during the mid and late Holocene is interpreted as being strongly controlled by changes in solar activity, in particular, the forcing of “grand solar minima” is recognized. Likewise, less frequent climate changes could be correlated with Bond cycles and increased or decreased activity of the Atlantic Meridional Overturning Circulation (also known as AMOC or the thermohaline), among other climate forcings such as volcanic activity.