Dansgaard-Oeschger climatic variability revealed by fire emissions in southwestern Iberia
Résumé
Paleoenvironmental records in Europe describing paleofires extending back to the Last Interglacial have so far been unavailable. Here we present paleofire results from the combined petrographic and automated image analysis of microcharcoal particles preserved in marine core MD95-2042 retrieved off southwestern Iberia and covering the last climatic cycle. The variability of microcharcoal concentrations reveals that the variability of fire emissions is mainly imprinted by the 23 000 yrs precessional cycle. A focus on the Last Glacial Period further shows that paleofires follow the variability of Dansgaard-Oeschger oscillation and Heinrich events and, therefore, parallel the variability of atmospheric temperatures over Greenland detected in ice cores. There is no evidence for fire increase related to human activity. The variability of fire emission by-products for the Last Glacial Period is interpreted in terms of changes in biomass availability. Low fire activity is associated with periods of drought which saw the development of semi-desert vegetation that characterised stadial periods. Fire activity increased during wetter interstadials, related to the development of open Mediterranean forests with more woody fuel availability.
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