Extreme cold–dry events in East Asia during glacials reflect insolation thresholds

Abstract Whether extreme climate events reflect intrinsic threshold behaviour of the climate system remains uncertain, in part because most terrestrial archives integrate multiple climatic signals and lack simultaneous constraints on temperature and hydroclimate. Here we present high-resolution ( ~ 900 years) quantitative reconstructions of land temperature and monsoon precipitation from the Chinese Loess Plateau spanning the past ~250,000 years, based on molecular fossil proxies. Using branched glycerol dialkyl glycerol tetraether (brGDGT) proxies for temperature and precipitation, together with complementary GDGT-based aridity indicators, our records reveal repeated extreme cold–dry events during glacial inceptions, in addition to pronounced droughts during glacial terminations. Although previous studies have provided key insights into past monsoon variability, these cold–dry extremes are not clearly expressed in widely used terrestrial proxies such as speleothem δ¹⁸O records, indicating that key aspects of continental climate variability have remained under-recognized. Transient climate simulations reproduce the timing of the extreme cooling events, providing model-based support for threshold-like climate responses to declining boreal summer insolation. Our findings suggest that such threshold-like behaviour may represent an important mode of continental climate responses to orbital forcing, providing a long-term perspective for assessing how regional climate extremes may emerge when background conditions approach critical thresholds.