Spatial analysis of paleoclimate variations based on proxy records in the south-central Andes (18°- 35° S) from 32 to 4 ka.

The long-term climate dynamics of the central Andes are part of an ongoing international research effort to reconstruct past climatic variations and sensitivity to different regional and global drivers during the last 50,000 years. The large number of diverse records, however, makes it difficult to compare results without an integrated spatial analysis that considers the nature of the record and whether they are integrating environmental conditions across a large basin (i.e., a lake record) or at a very local scale (such as a rodent midden). We compiled 92 records from the southern sector of the central Andes (SCA, 18°-35°S). Recalibrated records were further compared by converting the original author's interpretation into a scale of relative moisture anomalies (compared to the present) that ranges from −2 (very dry) to very wet (+2). Moisture anomaly maps were generated for intervals at 4, 6, 9.5, 14, 17, 21 and 32 ka BP (103 calibrated 14C years before present) using records within a 5% age uncertainty. Our compilations show a surprising degree of agreement in the extent and magnitude of past climate changes during late Pleistocene, but less spatial agreement during the Holocene. The TRACE21 transient climate model shows similar results, with better agreement during the Pleistocene compared to the Holocene. Our analyses not only reveal discrepancies between proxy record interpretations at sites from the same region but show which regions in the SCA require more study. • We compiled 92 paleorecords from the South-Central Andes and produced paleoclimate maps from 32 to 4 ky. • The wettest period in our maps occurs at 17 ky BP during Heinrich Event 1. • Holocene maps show much less spatial agreement than reconstructions for the Pleistocene. • Proxy-model comparisons using TRACE21 show better agreement in Late Pleistocene maps than for Holocene maps. • The most arid period recorded occurred in the map of 6 ky BP (Northgrippian). [ABSTRACT FROM AUTHOR]