What is really happening to Greenland icecap?

While recent observations indicate that the Greenland ice cap is melting fast, it is uncertain how much this is contributing to sea levels, as co-convenor Carl Bøggild, from UNIS in Svalbard explained. "A major challenge is to determine what fraction of melt water really runs off, because in many places the melt water will just drain into the cold snow and refreeze," said Bøggild.

One way to determine how much water is running off is to measure not just the area of the Greenland ice cap but also its thickness, but this is much more difficult. Alternatively, the run off process can be tracked both on the ground and by satellite, preferably integrating the two, as was discussed at the workshop. The need to establish a database of ground based observations, including run off, as well as the ongoing calving of ice bergs from the ice cap and occasional events such as earthquakes beneath the ice was discussed.

Perhaps the greatest immediate challenge identified at the workshop though lies in reducing the high levels of uncertainty over the current and future behaviour of the Greenland ice cap, and reconciling the many conflicting observations and predictions. In the case of the meltwater, estimates of the annual total vary by a factor of five from 50 gigatons (GT) to around 250 GT, and this level of uncertainty makes future predictions almost meaningless...