CLIMATE CHANGE DURING THE LAST GLACIATION IN THE NORTHERN GREAT BASIN INFERRED FROM NUMERICAL MODELING OF GLACIERS IN THE RUBY MOUNTAINS, NORTHERN NEVADA

Lamoille Canyon is the largest glacial valley in the Ruby Mountains and features terminal moraines deposited during the last Pleistocene glaciation. The changes in climate that accompanied glaciation and deglaciation – here and elsewhere in the Great Basin – have been inferred from a variety of proxies and span a broad range of possible temperature and precipitation combinations. Here, climate changes during this period are inferred from ice extents simulated by 2-D numerical modeling of glaciers at mass balance equilibrium. The goal of these model experiments is to limit the range of temperature and precipitation combinations during glaciation. The model results indicate that if precipitation was near modern to 40% greater than modern, then the temperature depression was ~9-10^°C. Modeling of glaciers in other valleys in the Ruby Mountains yields similar temperature and precipitation combinations for the last glaciation. When compared with previous glacier modeling experiments and other climate records of the last glaciation, these results indicate that the Ruby and Wasatch Mountains experienced a greater change in temperature or precipitation during the last glaciation compared to mountains elsewhere in Utah, Colorado and Wyoming. Furthermore, these results suggest that the magnitude of climate change during the last glaciation was greater in the Great Basin than in other surrounding regions.