Seasonality in northern South China Sea during the late Holocene

The annual temperature cycle is an important component of the Earth’s climate system. Here, the multiple snapshots sea surface temperature (SST) seasonality during past ~1600 years of northern South China Sea were reconstructed using monthly resolved δ¹⁸O and Sr/Ca profiles of fossil Tridacna and  coral skeletons. The results showed SST seasonality in northern SCS was contrary to temperature of China mainland and West Pacific Warm Pool, with a large seasonality during cold period (Little Ice Age, Dark Ages Cold period) and a small seasonality during warm period (Medieval Climate Anomaly). During Little Ice Age and Dark Ages Cold periods, strong East Asia Winter Monsoon (EAWM) and La Niña-like state of tropical Pacific Ocean promote a cold winter, and thus induce a large SST seasonality of northern SCS. During the Medieval Climate Anomaly, weak East Asia Winter Monsoon (EAWM) and El Niño-like state of tropical Pacific Ocean promote a warm winter, and thus induce a small SST seasonality of northern SCS.