2009 accumulation area ratios and little ice age equilibrium line altitude depression of Mount Baker glaciers, Washington state, USA

Measurements made from a 2009 NAIP (National Agriculture Imagery Program) orthoimage covering the Mount Baker area indicate that 2009 was a negative mass balance year: On average, the accumulation areas of the glaciers occupied only 37 percent of total glacier area at the end of August. An accumulation area of at least 62 percent is required for Mount Baker glaciers to be in equilibrium. Through the use of spreadsheet models, the modern and Little Ice Age thicknesses of these glaciers are compared. During the Little Ice Age, glaciers on Mount Baker were, on average, 1.6 times larger and approximately 20 m thicker than present. The equilibrium line altitudes of these glaciers were, on average, 300 m lower at the maximum of the Little Ice Age than today. The average ablation season temperature was about 2.0°C lower at the peak of the Little Ice Age than today, assuming that precipitation was 7% greater at that time.