Drastic change in Andean peatland carbon accumulation in the 1980s

Peatlands are globally significant carbon sinks; however, their response to recent climate warming remains poorly understood in tropical high-elevation regions. In the tropical Andes, rising temperatures, altered precipitation seasonality, and widespread glacier retreat over the past 65 years may have influenced peatland hydrology and carbon storage. Here, we reconstructed carbon accumulation rates (CARs) using four radiocarbon-dated peat cores from two Distichia muscoides –dominated high-Andean peatlands in the Central Peruvian Andes (APA1 and APA2). Basal ages ranged from 1957 to 1972 CE. CARs were exceptionally high, averaging 250 g C m -2 yr -1 at APA2 and 440 g C m -2 yr -1 at APA1, with peaks of up to 960 g C m -2 yr -1 , reflecting rapid peat accumulation and the high organic carbon content characteristic of D. muscoides . Both sites exhibited a pronounced decline in peat accumulation rates and CARs from the early 1980s. This decline coincided with a regional increase in air temperature as indicated by NCEP/NCAR Reanalysis data and was corroborated by a temperature-sensitive proxy based on the stable carbon isotope composition (δ 13 C) of Distichia , the trends of which exceeded those expected from changes in atmospheric δ¹³C–CO₂ alone. These findings indicate that warming-driven enhancement of organic matter decomposition has reduced net carbon sequestration. Our results demonstrate that high-Andean peatlands are highly sensitive to recent climate warming and hydrological stress, and future temperature increases are likely to further weaken their function as long-term carbon sinks.