Christian-Albrechts-University, Kiel, Germany.
Brown University, Providence, RI, USA.
Nat Commun. 2021 Apr 23;12(1):2406. doi: 10.1038/s41467-021-22739-3.
Understanding Earth's response to climate forcing in the geological past is essential to reliably predict future climate change. The reconstruction of continental climates, however, is hampered by the scarcity of universally applicable temperature proxies. Here, we show that heterocyte glycolipids (HGs) of diazotrophic heterocytous cyanobacteria occur ubiquitously in equatorial East African lakes as well as polar to tropical freshwater environments. The relative abundance of HG diols and keto-ols, quantified by the heterocyte diol index (HDI), is significantly correlated with surface water temperature (SWT). The first application of the HDI to a ~37,000 year-long sediment record from Lake Tanganyika provides evidence for a ~4.1 °C warming in tropical East Africa from the last glacial to the beginning of the industrial period. Given the worldwide distribution of HGs in lake sediments, the HDI may allow reconstructing SWT variations in polar to tropical freshwater environments and thereby quantifying past continental climate change.
了解地球在地质过去对气候强迫的响应对于可靠地预测未来气候变化至关重要。然而，大陆气候的重建受到普遍适用的温度代用指标稀缺的阻碍。在这里，我们表明固氮异形胞蓝藻的异形胞糖脂（HGs）普遍存在于东非赤道湖泊以及极地到热带淡水环境中。通过异形胞二醇指数（HDI）定量的 HG 二醇和酮醇的相对丰度与地表水温度（SWT）显著相关。HDI 首次应用于来自坦噶尼喀湖的长达约 37000 年的沉积物记录，为从末次冰期到工业时代初期东非热带地区变暖约 4.1°C 提供了证据。鉴于 HGs 在湖泊沉积物中的全球分布，HDI 可能允许重建极地到热带淡水环境中的 SWT 变化，从而量化过去的大陆气候变化。
