Document Type

Article

Publication Date

2010

Abstract

Equilibrium-line altitudes (ELAs) were determined from reconstructions of 22 paleoglaciers at their extent during the local last glacial maximum (LGM) using the accumulation-area method. LGM ELAs thus derived ranged from 2980 to 3560 m and follow a statistically significant regional trend of rising ~4.5 m km-1 to the east. Two approaches using a degree-day model were used to infer LGM climate by finding plausible combinations of temperature and precipitation change that (1) would be required to lower ELAs to their mean LGM values in both the Taylor Park/eastern Elk Mountains region and western Elk Mountains, and (2) provide steady-state mass balances to maintain individual glaciers. The results of these two approaches are convergent and suggest that in the absence of significant changes in precipitation, mean summer (or mean annual) temperatures within the study area during the LGM were on the order of about 7 degree C cooler than at present. The model also suggests that even allowing for modest changes in LGM precipitation (+/-25%), the required mean summer temperature depressions are within ~0.5 degree C of these values. Furthermore, there appears to be no significant dependence on small potential changes in temperature seasonality (i.e., winter temperatures). The inferred magnitude of LGM temperature change in the study area is consistent with other estimates from the broader Southern and Central Rocky Mountain region.

Comments

Definitive version available from Arctic, Antarctic, and Alpine Research, Vol. 42, No. 2, 2010 (https://instaar.colorado.edu/AAAR/journal_issues/abstract.php?id=2703).

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