Climate simulations and ice core data highlight the Holocene conundrum over tropical mountains

Abstract

Abstract Resolving discrepancies in long-term Holocene temperature trends between climate models and proxy records is essential to improve future climate projections. However, uncertainties in paleoclimate reconstructions limit their ability to constrain models. This study compares ice core-derived oxygen isotope records with isotope-enabled climate simulations to evaluate model performance and investigate Holocene temperature variability. Our results show that simulated and observed oxygen isotope trends in Greenland and West Antarctica are generally consistent, driven by orbital forcing. However, the model underestimates the early Holocene peak and subsequent decline observed in Greenland records. The most striking mismatch appears in tropical mountains, where the model shows a slight increase in isotopic trends, while proxy records indicate a clear decline. The mechanisms controlling this decreasing isotopic trend remain unclear and cannot be fully explained by temperature or hydroclimate changes alone. Addressing this tropical mountain oxygen isotope conundrum requires efforts to improve the model and paleoclimate interpretations.