Rapid warming of the planet has become a certainty and the sensitivity of the cryosphere plays a critical role in the earth’s future. Greenland’s outlet glaciers are particularly important because they deliver fresh water from the sensitive cryosphere to the world’s oceans, influencing sea level rise. Jakobshavn Isbrae is Greenland’s fastest outlet glacier draining approximately 7% of the entire Greenland Ice Sheet (Rignot and Kanagaratnam, 2006), and flowing up to 14km yr-1 (Bamber et al., 2007). However, the relationship that this calving margin has to climate remains unclear. For example, Howat et al. (2007) suggests that rapid changes in velocity and ice flux at the calving front are due to a change in geometry during short time intervals, but long-term discharge anomalies are due to climate change. To test this hypothesis, a better understanding of the calving front’s dynamical changes in response to these forcings needs to be assessed.

The position of Jakobshavn Isbrae’s calving front has retreated approximately 35 km in the last 150 years, 10 km within the last decade (Joughin et al, 2004). Greenland’s outlet glaciers, and especially Jakobshavn Isbrae, have abundant recorded observational knowledge on the monitoring of its extent. However, this knowledge is limited to velocity monitoring since the 1960s, and the terminus position since the late 1800s. With this information, total ice mass loss has not been assessed because detailed data on bed elevation and ice thickness were not available for most outlet glaciers. However, this study examines short-term variability in Jakobshavn Isbrae’s dynamics to test calving front responses to geometry and local temperature. This is done by evaluating ice flux changes of Jakobshavn Isbrae calculated between 1985 and 1986 using a Geographic Information System approach of surface velocity interpolation and ice thickness based on elevation.

Preliminary results show that Jakobshavn was discharging about 23 km3 yr-1 with maximum velocities reaching up to 20 m day-1 between 1985 and 1986. This has been a significant increase in Jakobshavn’s ice flux since Weidick et al. (1968) reported 16 km3 yr-1 in 1964. However, the calculated 1985 ice flux values are only half of that recorded in 2005 by Rignot and Kanagaratnam (2006). Other studies that have reported Jakobshavn’s ice flux are limited. They include ice fluxes at 24 km3 yr-1 in 1958 (Bauer, 1968), 37 km3 yr-1 in 1964 (Carbonnell and Bauer, 1968), 24 km3 yr-1 in 1996, and 46 km3 yr-1 in 2005 (Rignot and Kanagaratnam, 2006). These fluctuations in ice flux illustrate the complexity of Jakobshavn’s dynamical responses to climate and geometric changes. However, these findings will provide a better understanding of the total mass loss of a dynamic calving front and allow for better predictions of sea level rise with significant contributions of Greenland’s outlet glaciers.