New geochemical approach to reconstruct tropical palaeo-atmospheric dynamics (PYROWIND)

Description

The overall aim of the PYROWIND project is to develop an innovative palaeo-proxy approach to investigate the natural range of variability of key elements of the Hadley Circulation. Specifically, the project focusses on the intertropical convergence zone or ITCZ, which is a belt representing the convergence of northern and southern trade winds, where moist air is forced up and gives rise to the area of highest tropical precipitation. This new approach relies on the exploitation as climate proxy of an untapped but widespread material in marine sediments: pyrogenic carbon (PyC) derived from savannah and grassland fires and the deposition of biomass burning aerosols on the oceans. The South Atlantic will be the main test bed of the new approach as it is adjacent to the continents which have the most extensive and regular fire regimes worldwide. We propose that the Hadley Circulation plays a central role in the generation, transport and deposition of PyC from the continents to the deep ocean. We will undertake the spatial geochemical and isotopic characterization of pyrogenic carbon along with the analysis of mineral dust in tropical modern deep-sea sediments, water column and aerosols, and Pliocene-Pleistocene sediments. The goal is to design of a theoretical interpretative framework of PyC deposition in marine sediments to provide new constraints on the meridional natural variability of the ITCZ in contrasting climates. PYROWIND is possible thanks to the combination of cutting-edge knowledge of geochemical methodologies and in-depth interdisciplinary expertise on the palaeoclimatic study of marine sediments. We will provide new important datasets of windborne deep-sea PyC for testing and refining prediction models of atmospheric circulation, carbon cycle, precipitation and wildfires, issues which are of paramount global importance from scientific as well as societal standpoints.

Publications