Synchronity of meltwater pulse 1a and the Bølling warming: New evidence from the South China Sea

A twofold decrease in long-chain n-alcane (n-nonacosane) concentrations in a downcore record from the northern South China Sea indicates a rapid drop in the supply of terrigenous organic matter to the open South China Sea during the last deglaciation, paralleled by an equally rapid increase in sea-surface temperatures, corresponding with the Bølling warming at 14.7 ka. The sudden drop in terrigenous organic matter delivery to this marginal basin is interpreted to reflect a short-term response of local rivers to rapid sea-level rise, strongly implying that the Bølling warming and the onset of meltwater pulse (MWP) 1a are synchronous. This phase relation contrasts with the widely cited onset of this MWP 1a ca. 14 ka, and implies that previous studies postulating a weakening of deep-water formation in the North Atlantic due to massive meltwater discharge during MWP 1a need to be reevaluated.