Differentiating Westerly and Asian monsoon dust fluxes to the tropical Pacific Ocean since the late Pliocene

Asian dust flux is a fundamental regulator of global climate and marine biogeochemical cycles, yet it is difficult to separate the dust fractions delivered to the tropical Pacific Ocean by the Westerlies and East Asian Winter Monsoon (EAWM). We present a 4-million-year record of eolian evolution from the Philippine Sea to deconvolve these two distinct transport systems on the basis of grain-size modeling and geochemical fingerprinting. Our results show that the Westerlies component is primarily derived from hyper-arid deserts, whereas the EAWM-driven component originates from the semi-arid margins of East and Central Asia. Of importance is the finding that Westerly-driven transport reflects a coherent response to global cooling and hemispheric thermal gradients, whilst the Asia monsoon contribution is mediated by vegetation cover. We further demonstrate that hydroclimatic fluctuations in EAWM marginal zones modulate dust availability through vegetation-induced surface roughness and pedogenic refinement, resulting in a pronounced non-linear relationship between dust flux and wind energetics. This suggests the ecological conditions of dust source regions exert an impact on dust flux and thus the tropical ocean, necessitating integration of dynamic vegetation impacts and anthropogenic landscape interventions on dust into Earth System Models to predict global carbon cycling in a warming world. “Ecological conditions of dust source regions exert an impact on dust flux and thus on the tropical ocean, shown using grain size modeling and geochemical fingerprinting of a 4-million-year-long sediment record from the Philippine Sea”