LAUSR

The Jakobshavn Glacier (JG) in Greenland is one of the most active glaciers in the world. It was close to balance before 1997 but this was followed by a sudden transition to rapid thinning. The reason for the change remains unclear. In this study, The NASA Pre-IceBridge ice thickness data are collected to monitor the melting of JG front. The surface elevation decreased by around 90 m from 1995 to 2002 on the floating front. A distributed energy balance model is developed to estimate the energy balance of JG front in the past 30 years (1986–2016). The results indicate that multi-year average energy fluxes absorbed by the floating front of JG from the ocean were about 500 W m −2 from 1986 to 2016. This is approximately two times of the energy fluxes from atmosphere during the same period. The energy fluxes from the ocean increased from 200 to 600 W m −2 during the period from 1990 to 1998 while energy fluxes from the atmosphere remained stable at about 250 W m −2 . These results demonstrate that ocean contributes more to the melting of the JG front, and suggest that bottom surface melting must have a profound influence on marine terminating glacier dynamics.