El Niño–Southern Oscillation: Absent in the Early Holocene?

Abstract

High-resolution sedimentary proxies from low latitudes are rare but nevertheless important to understanding the role of tropical regions in the global climate. The reanalysis of a sedimentary record from Lake Pallcacocha (Andes) shows that ENSO was present throughout the Holocene. Even from 10?000 to 7000 calendar years before present, when the Tropics underwent a period of low variance, there is still evidence of a weak ENSO. This weakening, however, has been strongly overestimated. A frequency decomposition shows that all frequency components, except the millennial band (which has a different origin), covary synchronically for more than 6000 yr. A need to reconcile methodologies and results from climate studies at different time scales thus arises.