Pan-Arctic Sea-Ice Mass-Balance Observations: Status and Challenges

Sea ice is an important element of the arctic system, and its areal extent shows arguably the most dramatic change among all other elements, with fundamental consequences for the physical, biogeochemical, ecological and human domains. The observed reductions of summer ice extent are much more rapid than predicted by most climate models, pointing to a lack of understanding of the underlying processes governing the sea ice mass balance. In addition, there are only few systematic ice thickness measurements which could provide detailed information about mass balance changes due to ice redistribution and deformation, or due to variations in ocean and atmospheric heat fluxes. The presentation will review the current status of pan-arctic ice mass balance observations, including activities using ice profiling sonars, airborne laser and electromagnetic profiling, ice-mass-balance buoys, and satellite altimetry. Most recent results obtained by a consortium of researchers from Canada, Germany, Norway, the USA, and Russia will be presented, particularly from airborne electromagnetic sounding, which was performed in various regions of the Arctic and shows variable magnitudes of ice thickness change. The presentation will also discuss future activities and opportunities to enhance the observational data base, including efforts to establish a collaborative Canadian Arctic Sea Ice Mass Balance Observatory (CASIMBO) as part of a pan-arctic atmosphere-ice-ocean observing system. As long as satellite methods are not sufficiently validated, ice mass balance observations will depend on airborne, marine, or submarine logistics and surveys which gradually become more challenging particularly due to the increasing cost of fuel. Access to the Arctic Sea ice cover is a key challenge for the gathering of systematic pan-arctic ice mass balance data.