Essential gaps and uncertainties in the understanding of the roles and functions of Arctic sea ice

Abstract

While Arctic sea ice is changing, new observationmethods are developed and process understanding improves, whereas gaps in observations and understanding evolve. Some previous gaps arefilled, while others remain, or comeup new. Knowing about the status of observation and knowledge gaps is important for interpreting observation and research results, interpretation and use of key climate indicators, and for research and observation planning. This paper deals with identifying some of the important current gaps connected toArctic sea ice and related climate indicators, including their role and functions in the sea ice and climate systems. Subtopics that are discussed here include Arctic seaice extent, concentration, and thickness, sea-ice thermodynamics, age and dynamic processes, and biological implications of changing sea ice. Among crucial gaps are few in situ observations during the winter season, limited observational data on snow and ice thickness from theArctic Basin, andwide gaps in biological ratemeasurements in or under sea ice. There is a need to develop or improve analyzes and products of remote sensing, especially for new sensors and technology such as remotely operated vehicles. Potential gaps in observations are inevitably associatedwith interruptions in longtermobservational time series due to sensor failure or cuts in observation programmes.