Past climatic and environmental dynamics of the Atacama Desert evidenced in rodent middens pollen records

DE PORRAS, M.E; MALDONADO, A.; LATORRE, C.

Workshop; Workshop SHAPE and SWEEP; 2016

Past climate dynamics of the Atacama Desert (AD) has been studied because of two main reasons (1) its potential links with the continental and inter-hemispheric scale atmospheric circulation and (2) the strong impact that past climate variability would have had on the hydrologic resources of the most arid desert on the world. The present paper aims to trace the climatic and environmental dynamics of the AD during the last 16ka based on four pollen records from rodent middens distributed between 22°-24.9°S latitude. During the Late Glacial and the Pleistocene-Holocene transition widespread humid conditions prevailed in the AD but certain differences in timing and magnitude existed within the AD probably related to the prevailing source (tropical/extra-tropical) or mode (NNE/SE) of rainfall through time. Generalized extremely arid conditions occurred during the mid-Holocene associated to a northward shift of the ITCZ as a consequence of minimum insolation values at subtropical latitudes during the austral summer. The establishment of similar-to-present conditions occurred during the Late Holocene. The climatic variability that characterizes the AD during this period associated either with increased frequency of tropical rainfall during La Niña episodes or extra-tropical precipitation incursions, is not reflected by our rodent midden pollen records. Acknowledgements: FONDECYT #11150089, 3130511, 1130279, CONICYT-PIA-SOC1405