Climatic Impact of the Little Ice Age on Sumatra, Indonesia

The Little Ice Age was a period of colder climate and extended glaciation mainly observed in Europe and North America between the middle of the 14^th and the end of the 19^th century. However, the climatic impact of the Little Ice Age on tropical regions is still unclear. In this study, we sampled two short (1m), dated sediment cores (MJ17-01A-G and MJ17-01B-G) that were taken in 2017 within Lake Maninjau for leaf wax compound-specific analysis. Lake Maninjau is a 99.5 km² caldera lake located at the equator in the Padang Highlands on the Island of Sumatra, Indonesia. Here, we extracted leaf-wax compounds of 34 samples – so called n-alkanes – measured their concentration and calculated the average chain length (ACL) and carbon preference index (CPI) of the individual samples. The ACL is a first-order proxy for overall humidity/precipitation and ranges between carbon numbers of C₂₆ and C₃₁ with a trend to lower values towards the top of the section. We interpret this shift from higher to lower ACL-values to represent a shift from dryer to more humid conditions between 1550 and 1850 AD in the period of the Little Ice Age and into the modern. We interpret that the Little Ice Age in Europe and North America indeed also affected tropical regions like Southeast Asia.