Chironomid-based Holocene summer temperature dynamics from southern Spain

This study presents a reconstruction of Holocene mean July air temperatures based on chironomid assemblages preserved in the sedimentary record of Laguna de la Mosca (LdlMo), an alpine lake in the Sierra Nevada of southern Spain. The LdlMo record reveals that the highest temperatures occurred during the Early and early-Middle Holocene, between 8500 and 7000 cal yr BP, followed by a significant cooling event. During the Middle Holocene, temperatures stabilized, but a second major cooling event occurred at approximately 4200 cal yr BP, possibly associated with the 4.2 kyr event. Throughout the Late Holocene, temperatures generally remained low, punctuated by warming episodes between 2300–1600 cal yr BP during the Iberian Roman Humid Period (IRHP) and around 1000 cal yr BP during the Medieval Climate Anomaly (MCA). The lowest temperatures were recorded at the end of the Little Ice Age (LIA), circa 1800 CE. Since ~1955 CE, a rapid and pronounced warming trend of 2.5°C has been observed, driven by anthropogenic climate change. This study shows the amplification of recent warming at high elevations, highlighting the vulnerability of these fragile and unique alpine environments to the impact of climate change.

This work was funded by grants BIOD22_001 and BIOD22_002, funded by Consejería de Universidad, Investigación e Innovación and Gobierno de España and Unión Europea – NextGenerationEU and PID2021-125619OB-C21 funded by the Ministerio de Ciencia e Innovacion of Spain, the Agencia Estatal de Investigacion and the Fondo Europeo de Desarrollo Regional FEDER MCIN/AEI/10.13039/501100011033/FEDER, UE