Northern Iberian abrupt climate change dynamics during the last glacial cycle: A view from lacustrine sediments

Abstract

We present a palaeoclimatic reconstruction of the last glacial cycle in Iberia (ca. 120,000–11,600 cal yrs BP) based on multi-proxy reconstructions from lake sediments with robust chronologies, and with a particular focus on abrupt climate changes. The selected lake sequences provide an integrated approach from northern Iberia exploring temperature conditions, humidity variations and land-sea comparisons during the most relevant climate transitions of the last glacial period. Thus, we present evidence that demonstrates: (i) cold but relatively humid conditions during the transition from MIS 5 to MIS 4, which prevailed until ca. 60,000 cal yrs BP in northern Iberia; (ii) a general tendency towards greater aridity during MIS 4 and MIS 3 (ca 60,000 to 23,500 cal yrs BP) punctuated by abrupt climate changes related to Heinrich Events (HE), (iii) a complex, highly variable climate during MIS 2 (23,500 to 14,600 cal yrs BP) with the “Mystery Interval” (MI: 18,500 to 14,600 cal yrs BP) and not the global Last Glacial Maximum (LGM: 23,000 to 19,000 cal yrs BP) as the coldest and most arid period. The last glacial transition starts in synchrony with Greenland ice records at 14,600 cal yrs BP but the temperature increase was not so abrupt in the Iberian records and the highest humidity was attained during the Allerød (GI-1a to GI-1c) and not during the Bølling (GI-1e) period. The Younger Dryas event (GS-1) is discernible in northern Iberian lake records as a cold and dry interval, although Iberian vegetation records present a geographically variable signal for this interval, perhaps related to vegetation resilience.