Strengthened East Asian winter monsoon associated with insolation and Arctic sea ice since the middle Holocene

The East Asian winter monsoon (EAWM) is one of the most important Asian climate systems, with a huge influence on social, agricultural productivity, and economic development. Sub-orbital-scale variations of the East Asian winter monsoon (EAWM) since the mid-Holocene and its associated mechanisms, however, are still not fully understood. Based on a high-resolution transient simulation, here we present a continuous climate evolution of EAWM in response to orbital forcing. Similar to the record proxy, the simulated EAWM variations exhibit a strengthening trend since the mid-Holocene, especially in the spring. Following the orbitally-induced decay of Northern Hemisphere summer insolation during the Holocene, growing Arctic Sea ice persists into winter and increases the latitudinal temperature gradient between low- and high latitudes, which lead to the strengthening of wintertime EAWM. While the intensified springtime EAWM can be attributed to the enhanced temperature gradient caused by solar insolation at different latitudes, rather than local insolation. Our results indicate that insolation forcing and Arctic Sea ice have played a key role in driving Holocene EAWM changes by enhancing temperature gradient between low and high latitudes.