High elevation ice patch documents Holocene climate variability in the northern Rocky Mountains

Paleoclimate records from ice cores generally are considered to be the most direct indicators of environmental change, but are rare from mid-latitude, continental regions such as the western United States. High-elevation ice patches are known to be important archaeological archives in alpine regions and potentially could provide records important for Earth System Model evaluation and to understand linkages between climate and early human activities, but this potential largely is unexplored. Here we use a well-dated ice-core record from a shallow ice patch to investigate Rocky Mountain winter-season climate during the Holocene. Our records indicate that this ice patch consistently accumulated ice over the past 10 kyr, preserving a regionally representative climate record of stable water isotopes and ice accretion rates that documented generally cooler and wetter conditions during the early Holocene and 500 years of anomalous winter season warmth centered at 4100 cal yr BP followed by a rapid cooling and 1500 years of cooler and wetter winters.