El efecto de la “isla seca” en el clima de las regiones altoandinas durante el Holoceno tardío

The interhemispheric movement of the intertropical convergence zone (ITZC) at different time scales plays a fundamental role in the distribution of precipitation in the tropics of the American continent. This latitudinal transition is recorded in paleoclimatic archives as an inverse signal in both hemispheres. When the ITCZ is located at a more northern mean position, sedimentary records indicate wet conditions in the tropics of the northern hemisphere and dry conditions in the tropics of the southern hemisphere. Opposite conditions are recorded when the ITCZ is located over the tropics of the southern hemisphere. Recent studies on lake sediment cores in Tota and Siscunsí Lakes in the high Andean regions of Colombia indicate dry conditions during the Medieval Climate Anomaly, a period for which there is evidence of an ITCZ positioning in the northern hemisphere, and high relative humidity conditions during the Little Ice Age when the ITCZ was located over the southern hemisphere tropics. This paper discusses the possibility of the “dry island” effect as a possible explanation of these paleoclimate results that differ from the paradigm that proposes ITCZ as one of the main mechanisms explaining Neotropical climate variability at different time scales.