Holocene temperature and environmental reconstruction from Llanos de Moxos in western Amazon based on GDGTs

The Holocene temperature history of the lowland Amazon Basin remains poorly constrained, even though the region plays a key role in global climate, carbon cycling, and biodiversity. We present a Holocene record of glycerol dialkyl glycerol tetraethers (GDGTs) from a lake sediment core in the westernmost Amazon Basin, Bolivia, providing new constraints on regional temperature evolution and lake environmental conditions. The brGDGT based temperature reconstruction reveal a low amplitude, gradual warming trend throughout the Holocene. This pattern is consistent with other terrestrial records from tropical South America but contrasts with compiled tropical and global temperature reconstructions that suggest more pronounced early to mid-Holocene warmth followed by cooling. Our results therefore support the hypothesis that Holocene temperature evolution in tropical South America was distinct from that of other low latitude regions and from the global mean, highlighting the importance of regional climate dynamics and land surface feedbacks in shaping tropical climate trajectories.

In addition to temperature, GDGT distributions indicate four distinct phases of changing lake conditions over the Holocene, characterized by shifts in productivity and bottom water redox conditions. These variations likely reflect changes in local landscape development and catchment processes, as well as alterations in wind driven lake mixing. The most recent interval shows signatures consistent with enhanced productivity which may be linked to human activity in the catchment.

Together, these results provide new insights into the long-term temperature history of the western Amazon Basin and demonstrate the value of GDGTs for simultaneously reconstructing regional climate trends and lake environmental change in tropical lowland settings.