Tropical volcanism enhanced the East Asian summer monsoon during the last millennium

Abstract

Extreme East Asian summer monsoon (EASM) rainfall frequently induces floods that threaten millions of people, and has been generally attributed to internal climate variability. In contrast to the hydrological weakening theory of volcanic eruptions, here we present convergent empirical and modeling evidence for significant intensification of EASM rainfall in response to strong tropical volcanic eruptions. Our multi-proxy analyses show a significantly increased EASM in the first summer after tropical eruptions from 1470 AD to the present, and the more frequent occurrence of El Niños in the first boreal winter after eruptions is necessary for the enhanced EASM. Model simulation ensembles show that a volcano-induced El Niño and the associated stronger than non-volcanic El Niño warm pool air-sea interaction intensify EASM precipitation, overwhelming volcanic-induced moisture deficiency. This work sheds light on the intertwined relationship between external forcing and internal climate variability and potential flood disasters resulting from tropical volcanic eruptions.

Relative Roles of Land and Ocean Cooling in Triggering an El Niño Following Tropical Volcanic Eruptions

“…El Niños were observed following four out of the five large tropical volcanic eruptions over the past 150 years, which are 1902 Santa Maria eruption, 1963 Agung eruption, 1982 El Chichón eruption, and 1991 Pinatubo eruption, except for 1883 Krakatau eruption, suggesting the linkage between tropical eruptions and the following El Niños (Handler, 1984; Khodri et al., 2017; Liu et al., 2020; Mcgregor et al., 2020; Xing et al., 2020). This temporal linkage was also reported in paleoclimate analyses (Adams et al., 2003; D'Arrigo et al., 2009; Liu et al., 2018; 2022; Mcgregor et al., 2010, 2020; Robock, 2020; Wilson et al., 2010), although some reconstruction results, especially based on fossil corals from the central tropical Pacific, disapproved of such linkage that tropical eruptions can increase the likelihood of El Niño (Dee et al., 2020; Zhu et al., 2022).…”

“…Different from observation and paleo-reconstruction in which the El Niño is usually observed during the first boreal winter after tropical volcano eruptions (Khodri et al, 2017;Liu et al, 2018Liu et al, , 2022, CESM simulates the El Niño in the second winter, even in the Land scenario without the ocean cooling induced by aerosol forcing over the ocean. Here, we only simulated the volcano erupted in June and the forcing peaked in October, the El Niño therefore didn't have enough time to develop before the winter.…”

“…The coupled CESM1.2 is used in this work due to its good simulation of ENSO in terms of seasonality, frequency, and associated teleconnection (Bellenger et al, 2014;Capotondi et al, 2020) and the ability to simulate El Niño response to large tropical eruptions (Liu et al, 2018(Liu et al, , 2022Stevenson et al, 2016Stevenson et al, , 2017Yang et al, 2022), although the internal ENSO variation is stronger than observation (Stevenson et al, 2016). The atmosphere model is Community Atmosphere Model version 5.0 (CAM5) and is coupled with the Parallel Ocean Program version 2 (POP2) and the Community Land Model version 4.0.…”

A Physics‐Based Empirical Model for the Seasonal Prediction of the Central China July Precipitation

“…El Niño‐South Oscillation (ENSO), as a dominant source of interannual climate variability worldwide, often matures in boreal winter but can cause lagged effects on the East Asian climate until the following summer (Kosaka et al., 2013; T. Li et al., 2017; F. Liu, Gao, et al., 2022; Sun et al., 2021; Takaya et al., 2021; B. Wang et al., 2000; M. Wu et al., 2020; X. Wu et al., 2021; Xie et al., 2009; J. Yang et al., 2007; Z.‐Q. Zhou et al., 2018).…”

Decadal variability of precipitation over the Tibetan Plateau modulated by the 11-year solar cycle over the past millennium

“…In contrast, Misios et al (2019) used multiple regression analysis to suggest a weakened Pacific Walker circulation at solar cycle maxima, caused by a thermodynamics-induced muted hydrology mechanism. Both the ENSO-like and PDO-like SST patterns under solar forcing can further influence precipitation over eastern China (Ma et al, 2021;Liu et al, 2022;Xue et al, 2022). However, the effect of the 11-year solar activity cycle on TP precipitation remains unknown.…”