A method for climatic reconstruction of the Mediterranean Pliocene using pollen data

Pollen data from numerous sites around the Mediterranean Sea indicate that several important vegetation and climatic changes occurred during the Pliocene. These data are in good agreement with pollen records from northwest Europe and with δ18O curves from Mediterranean and Atlantic deep-sea cores. Quantitative palaeoclimatic reconstructions from Pliocene pollen data of the Mediterranean region cannot be based on conventional modern analogue techniques, as individual Pliocene pollen spectra contain taxa representing temperate, warm-temperate and subtropical plants that do not grow together today. Instead, we propose a new method that uses a climatic amplitude method modified to take partially into account the relative abundances of the taxa. We applied this method to the Pliocene Garraf 1 palynological sequence from Catalonia, which provides a long continuous record of climatic change from 5.3 Ma to the Early Pleistocene. We estimate that annual temperatures were 1 to 5°C higher than today and the annual precipitation 400 to 1000 mm higher than today prior to the beginning of the late Cenozoic glacial–interglacial cycles. In contrast, temperature and precipitation both fell sharply during the glacial phases of the earliest glacial–interglacial cycles.