Climate variability during the last 1000 years inferred from Andean ice cores: A review of methodology and recent results

Andean ice core investigations began approximately 30 years ago. Today, 10 drilling sites, from 0° to 52°S, have been explored for paleoclimate reconstructions. Most of the ice cores reaching the bedrock cover the last 20,000 years with seasonal resolution over the last few centuries to the last 1000 years for the Quelccaya site. We discuss both the potential and the limitations of tropical ice cores as climate archives with regard to the collaborative effort to reconstruct past climate variations in South America over the last 1000 years. We point out the uniqueness of South American ice cores, due to their location at high altitude, and also their two main limitations, which are related to (i) the interpretation of certain proxies in terms of climate and (ii) the relatively poor dating when seasonal cycles are no longer resolved. In addition, we present an overview of the proxies that have been used so far to analyze tropical climate dynamics. Finally we discuss records of ENSO, the Little Ice Age and the 20th century decadal variability, including the anthropogenic period, which are all preserved in ice cores.