African vegetation controlled by tropical sea surface temperatures in the mid-Pleistocene period

Abstract

The dominant forcing factors for past large-scale changes in vegetation are widely debated. Changes in the distribution of C4 plants adapted to warm, dry conditions and low atmospheric CO2 concentrations have been attributed to marked changes in environmental conditions, but the relative impacts of changes in aridity, temperature and CO2 concentration are not well understood. Here, we present a record of African C4 plant abundance between 1.2 and 0.45 million years ago, derived from compound-specific carbon isotope analyses of wind-transported terrigenous plant waxes. We find that large-scale changes in African vegetation are linked closely to sea surface temperatures in the tropical Atlantic Ocean. We conclude that, in the mid-Pleistocene, changes in atmospheric moisture content driven by tropical sea surface temperature changes and the strength of the African monsoon controlled aridity on the African continent, and hence large-scale vegetation changes.