Search

The influence of recent global warming on the intensity, timing, and extent of the East Asian summer monsoon (EASM) remains not fully understood. Here we reconstruct an EASM precipitation history of the past ~ 500 years based on sedimentary multi-proxy indices from Lake Daihai, northern China. We find low EASM precipitation between ~ AD 1517 and ~ 1850, with three sharply weakened intervals, which were broadly concurrent with the Chinese dynastic and cultural transitions. The EASM intensified after ~ AD 1850, changing from cold-dry to warm-wet conditions, with greater multidecadal variability. These features match well with the coeval sea surface temperature (SST) records over the North Pacific and North Atlantic Oceans, suggesting that changes in global SSTs could have forced changes in EASM intensity and modulated regional hydroclimate on these timescales. We propose that the increased interhemispheric temperature gradients associated with the recent global warming might push northward the western Pacific Subtropical High (WPSH), the westerlies, and the monsoon front. Meanwhile, the multi-decadal warming in the North Atlantic may also strengthen the westerlies and the EASM. These multiple factors could have collectively led to higher precipitation in the converging zone of the westerlies and the WPSH since ~ AD 1850. [ABSTRACT FROM AUTHOR]

Rain‐belt migration, and in particular monsoon migration, are a cardinal, yet under‐constrained aspect of climate change. Here, we present a new lake‐level record from a closed‐basin lake in northern China and a compilation of available lake level records from closed‐basin lakes located at the northern margins of East Asian and Indian monsoon regions. These data show that ca. 6 ka ago, changes in water availability, as recorded by the surface areas of the closed‐basin lakes, shrunk dramatically, within a few decades, and have not been restored to their pre‐6 ka sizes since. These data imply that the Indo‐East Asian monsoon systems underwent a large coeval southward contraction, which preceded the gradual decline in insolation forcing, and abruptly ended the Holocene Humid Period (HHP). This new compilation enables to constrain potential feedback mechanisms involved in the early termination of the HHP at the monsoon fringes. Plain Language Summary: A cardinal question in climate research is how and why rain‐belts shift under different climatic conditions. Here we show, that ∼6,000 years ago the surface areas of nine closed‐basin lakes located at the northern margins of the East Asian and Indian monsoon regions shrunk dramatically, within a few decades, and have not been restored to their pre‐6 ka sizes since. These data suggest that an abrupt, large scale, southward contraction of the Asian monsoons ended the Holocene Humid Period, and caused large scale desertification at the monsoonal fringes. Key Points: Lake‐levels of closed‐basin lakes at Asian monsoon margins were high during the early‐middle Holocene and dried out abruptly ∼6 ka agoA lake‐level record from north China provides unprecedented age and rate resolution of monsoon decline at Holocene Humid Period terminationAsian monsoon margin lakes dried out earlier then vegetation change thus, "vegetation feedback" was not a leading factor of monsoon decline [ABSTRACT FROM AUTHOR]

The history and mechanisms of dust storms in northern China remain unclear owing to the paucity of reliable long-term, high-resolution geological records. In this study, we reconstructed the dust storm history of the last ~500 years in northern China, based on sedimentary coarse fraction (>63 µm) of a well-dated core from Lake Daihai, Inner Mongolia. The high-resolution data reveal three intervals of frequent dust storms: AD 1520–1580, AD 1610–1720, and AD 1870–2000. The dust storm events in the Lake Daihai area were broadly synchronous with those inferred from other historical or geological records and generally occurred during cold intervals. Changes in the intensity of Siberian High and the westerlies modulated by temperature variations are the likely major factors controlling dust storm dynamics. An interesting feature is that although the intensities of dust storms have been systematically increased during the recent warming period, a clear decreasing trend within this period is evident. The recent increase in average dust storm intensity may be ascribed to an increase in particle supply resulting from a rapid increase in human activity, whereas the weakening trend was likely caused by decreases in average wind speed resulting from the recent global warming. [ABSTRACT FROM AUTHOR]