LAST GLACIAL MAXIMUM EQUILIBRIUM-LINE ALTITUDE AND PALEO-TEMPERATURE RECONSTRUCTIONS FOR THE CORDILLERA DE MÉRIDA, VENEZUELAN ANDES

The pattern and magnitude of glacier equilibrium-line altitude (ELA) lowering in the tropics during the Last Glacial Maximum is currently a topic of debate. Nine paleo-glaciers in the Venezuelan Andes were reconstructed using field observations, aerial photographs, satellite imagery and high-resolution digital topographic data to better understand tropical climate change and its forcing mechanisms. Many published reports rely on techniques that underestimate the amount of tropical ELA lowering during the LGM. Here, paleo-glacier equilibrium-line altitudes (ELAs) were estimated using the accumulation-area ratio (AAR) and the area-altitude balance ratio (AABR) methods that take into account the total glacier surface area. During the local LGM in Venezuela (~22,750 to 19,960 cal yr BP), ELAs were ~870 to 1420 m lower than present. Temperature estimates are at least 8.8 ± 2°C cooler than today based on a combined energy and mass-balance equation to account for an ELA lowering. This is greater than estimates using an atmospheric lapse rate calculation, which yields a value of 6.4 ± 1°C cooler.