Chironomid-inferred July-air temperature of Lago Piccolo di Avigliana

Chironomid headcapsules were used to reconstruct late glacial and early-Holocene summer temperatures at Lago Piccolo di Avigliana (LPA). Two training sets (northern Sweden, North America) were used to infer temperatures. The reconstructed patterns of temperature change agreed well with the GRIP and NGRIP d18O records. Inferred temperatures were high during the Bølling (ca 19 °C), slowly decreased to ca 17.5 °C during the Allerød, reached lowest temperatures (ca 16 °C) during the Younger Dryas, and increased to ca. 18.5 °C during the Preboreal. The amplitudes of change at climate transitions (i.e. Oldest Dryas/Bølling: 3 °C, Allerød/Younger Dryas: 1.5 °C, and Younger Dryas/Preboreal: 2.5 °C) were smaller than in the northern Alps but similar to those recorded at another site in northeastern Italy. Our results suggest that (1) Allerød temperatures were higher in the southern Alps and (2) higher during the Preboreal (1 °C) than during the Allerød. These differences might provide an explanation for the different responses of terrestrial-vegetation to late glacial and early-Holocene climatic changes in the two regions. Other sites on both sides of the Alps should be studied to confirm these two hypotheses.本研究以摇蚊头壳（Chironomid headcapsules）重建了阿维亚纳小湖（Lago Piccolo di Avigliana, LPA）的晚冰期及早全新世夏季气温。研究采用瑞典北部、北美两个训练集开展气温反演。重建得到的气温变化格局与格陵兰冰芯项目（GRIP）及北格陵兰冰芯项目（NGRIP）的δ¹⁸O记录契合度极佳。反演结果显示，气温在博林暖期（Bølling）约为19℃，处于高位；阿勒罗德暖期（Allerød）缓慢降至约17.5℃；新仙女木期（Younger Dryas）达到最低值（约16℃）；前北方期（Preboreal）回升至约18.5℃。各气候转型期的气温变幅（即最老仙女木期（Oldest Dryas）/博林暖期：3℃、阿勒罗德暖期/新仙女木期：1.5℃、新仙女木期/前北方期：2.5℃）小于北阿尔卑斯地区，但与意大利东北部另一遗址的记录相近。本研究结果表明：（1）南阿尔卑斯地区的阿勒罗德暖期气温更高；（2）前北方期气温较阿勒罗德暖期高出约1℃。上述差异或可解释两地陆地植被对晚冰期及早全新世气候变化的不同响应。后续需对阿尔卑斯山脉两侧的其他遗址开展研究，以验证这两项假说。