MID LATITUDE GLACIAL RESPONSES TO ENSO IN THE EASTERN PACIFIC: A TALE OF TWO HEMISPHERES

Changes in average temperatures and precipitation associated with ENSO conditions can have significant impacts on glacial ablation and accumulation patterns. Despite the large role ENSO plays in Pacific weather variations, a comparison of its effects on coastal glaciers in both the Northern and Southern Hemispheres has not been quantified in previous research. We present here evidence of variable ENSO effects across mid-latitude glaciers along the Pacific Coast of Canada and Chile. Our findings indicate significant changes in glacial area and rates of accumulation during times of strong ENSO variations, with significant differences observed in the Northern and Southern hemispheres. Two comparable glaciers were chosen to study-- Homathko Icefield in British Columbia, Canada and the Northern Patagonian Icefield in Chile. Both glaciers are located at similar latitudes (Homathko Icefield at 51°05′N and Northern Patagonian Icefield at 47°00′S) and elevations (ranging from approximately 5000-8000ft). GIS analysis of Landsat satellite images was conducted to measure glacial areas through annual and seasonal (Dec-Feb and Jun-Aug) intervals. We saw a stronger correlation between ENSO conditions and glacial area in the Southern Hemisphere than in the Northern Hemisphere, particularly during heightened El Niño conditions as measured by the Multivariate ENSO Index (MEI). During El Niño conditions in the Southern Hemisphere, we observed greater than average glacial areas and rates of winter accumulation. Climate anomaly data for these times show cooler to moderately warmer temperatures and significantly increased levels of precipitation. Understanding how glaciers respond regionally to large-scale circulation patterns such as ENSO gives context to seasonal changes we see currently. As more information is gathered on how ENSO patterns will be impacted by climate change, our findings have the potential to gain greater significance in predicting glacial responses to a changing climate.