Annual-resolution evidence for aridity spikes at the onset of the Last Glacial Inception in an Eifel maar lake sediment.

This study presents an annually laminated sediment record from the infilled maar lake at Hoher List in the Eifel volcanic field (Germany), documenting the "Last Glacial Inception" (LGI) at the end of the Eemian interglacial. The landscape of the late Eemian was dominated by a mixed forest containing Abies alba (silver fir). The collapse of this forest occurred within only a few years and was accompanied by frequent wildfires, aeolian dust deposition, a decline of all thermophilous tree species, and the disappearance of Abies, all indicating increasing aridity. The transition unfolded in three distinct phases. LEAP-I (Late Eemian Aridity Pulse I) lasted approximately 250 years and was followed by a 750-year recovery phase during which the interglacial forest returned. LEAP-II was characterized by comparable arid conditions but persisted for at least 750 years, followed by a 350-year phase of boreal forest development. The final transition to stadial conditions occurred during LEAP-III, marked by a pronounced lake-level decline, expansion of grassland, scattered birch and pine, and reduced summer temperatures, likely corresponding to North Atlantic cold event C25. The LGI lasted at least 2700 years, whereas individual aridification pulses developed within decades, indicating rapid aridification events superimposed on a long-term cooling trend.