Climate During the Last Glacial Maximum in the Southern Sangre de Cristo Mountains, Colorado, U.S.A.

Reconstruction of seven paleoglaciers in the southern Sangre de Cristo Mountains of Colorado formed the basis of temperature-index modeling to estimate the magnitude of temperature change during the Last Glacial Maximum (LGM). The model is used to determine temperatures and precipitation that would maintain steady-state mass balance of the glaciers at their maximum LGM extents. If precipitation was similar to that today, modeling suggests that LGM mean annual temperatures were between ~8.9 and 10 °C cooler, with associated uncertainties of ±1 °C. Modest increases in precipitation (i.e., 100 mm yr−1) that are indicated by some climate modeling do not appreciably lower the magnitudes of temperature depression required for steady-state mass balances. While these new estimates of temperature depression in the Colorado Rocky Mountains align with some that were similarly derived, they are significantly greater (cooler) than others. However, they are consistent with regional-scale climate models as well as high-resolution downscaling of global LGM climate for the Sangre de Cristo.