Cyclic rapid warming on centennial-scale revealed by a 2650-year stalagmite record of warm season temperature

A 2650-year (BC665-AD1985) warm season (MJJA: May, June, July, August) temperature reconstruction is derived from a correlation between thickness variations in annual layers of a stalagmite from Shihua Cave, Beijing, China and instrumental meteorological records. Observations of soil CO2 and drip water suggest that the temperature signal is amplified by the soil-organism-CO2 system and recorded by the annual layer series. Our reconstruction reveals that centennial-scale rapid warming occurred repeatedly following multicentenial cooling trends during the last millennia. These results correlate with different records from the Northern Hemisphere, indicating that the periodic alternation between cool and warm periods on a sub-millennial scale had a subhemispherical influence.