Glacial induced variations in the uplift – a challenge for the reference frame

Arctic areas are heavily affected by climate change. The temperature is increasing, the permafrost is melting, the sea ice is disappearing, and the glaciers are retreating. The elastic response of the changes in the glacier affects the earth crust. Locally on Greenland or Svalbard the uplift can reach several centimetres per year. The ice melting in Greenland is so large that it affects the land uplift in large parts of the Northern hemisphere.

The geodetic observatory in Ny-Ålesund is a key station in the global geodetic network. It is the northern most fundamental station, containing all the main geodetic techniques and important for the realisation of the ITRF. However, its stability has been questioned. The observatory experience variations in the uplift on seasonal, inter-annual, decadal and longer timescales. The uplift for a moving window of 5-years periods has increased from below 6 mm/yr in the 1990 to more than 12 mm/yr today. This has challenged the realisation and stability of global and regional reference frames. 

We have modelled the elastic response of glacier changes based on various glaciological sources. These results will be presented. We will in particular compare the elastic uplift with geodetic time-series from Ny-Ålesund and other GNSS in Svalbard and discuss how this could affect reference frames. Could for instance the VLBI scale issue in ITRF2020 be related to glacial changes? 

We found that the variations in the uplift can be explained by the glacier changes and close to 50% of the VLBI scale drift can be explained by glacier related accelerating uplift.