Tree-ring δ18O reveals a consistent decrease in April precipitation in southeastern China since the 1950s and its linkage to global climate phenomena

Abstract

The East Asian Summer Monsoon (EASM) precipitation in southeastern (SE) China has intraseasonal evolution, unique characteristics, and complex drivers. Within the EASM, April precipitation plays a crucial role in the first rainy season (FRS) precipitation. Accurately quantifying the long-term temporal variability of FRS precipitation is essential for enhancing monthly and seasonal precipitation forecasts. This study presented the hitherto longest tree-ring δ¹⁸O chronologies (LSMδ¹⁸O) of Cryptomeria fortune trees spanning 201 years (1816–2016 CE) from Fujian province in SE China. The LSMδ¹⁸O chronology showed the strongest negative correlation with monthly precipitation in April ( r = −0.59, p < 0.001) for the calibration period 1951–2016 CE, indicating a strong association between the tree-ring δ¹⁸O signature and FRS precipitation variability. This relationship enabled the first reconstruction of April precipitation (reconstructed PRE<inf>Apr</inf>) in SE China for the period 1856–2016 CE. A total of 30 % (48 events) of precipitation anomalies were observed in the reconstruction. The low-PRE<inf>Apr</inf> anomalies were identified, for example, in 1875, 1895, 1902, 1987, 1998, and 2004 CE. Reconstrued PRE<inf>Apr</inf> revealed spectral peaks of 2–7 years high-frequency periodicities associated with El Niño–Southern Oscillation activities due to higher sea surface temperature variation at the tropical Pacific Ocean. The reconstructed PRE<inf>Apr</inf> effectively captured the synchronous precipitation shifts across SE China and the western Pacific domain, indicating an anomalous declining trend in the large-scale precipitation changes since the 1950s CE. The seasonal extreme precipitation events associated with rising Northern Hemisphere temperatures have become more frequent and severe in SE China under a warming climate.