High-Resolution Tropical Temperature Records Inferred from Tree-Ring Isotopes

DESCRIPTION: In the last decades, the Central Andes experienced a persistent warming and drying trend, together with an increasing growing demand for water resources. The scarcity of reliable and long instrumental climate data have prevented to place the current warming in a long-term context that would contribute to a better management of water resources. Tree rings provide information about past climate variability and a better understanding of the full range of climate variability (annual, decadal and centennial). While most of the high-resolution temperature reconstructions in temperate regions are based on year-to-year variability in the width of the rings, very little success have occurred in tropical areas.

Here, we will leverage unique wood material from 700-year old trees of Polylepis tarapacana, the highest elevation tree specie worldwide, to measure carbon and oxygen stable isotopes. Samples were collected about 4000 m asl in Bolivia and Chile along a latitudinal gradient over the high altitude plateau, the so-called ‘Altiplano’. The samples are currently available at the Tree-Ring Laboratory due to the ongoing THEMES project. While annual reconstructions of ENSO and precipitation variability in tropical and subtropical montane dry areas have been generated using this tree species, from our knowledge, land surface temperature was never attempted. We expect that this isotopic data will allow us to generate the first high-resolution land surface temperature network in the tropics in South America.