Challenges in simulating sea ice in Earth System Models

Sea ice is a key element of the Earth's climate system, and also of significant ecological, geo‐political, and economic importance. Understanding the ongoing changes of the Earth's sea‐ice cover is therefore not only scientifically interesting in itself, but also crucial for a large number of different stakeholders. Without such understanding, a reliable projection of possible future changes will be impossible. A main focus of ongoing sea‐ice research is therefore aimed at identifying the factors that modulate the ice's variability on seasonal and longer time scales. For such efforts, coupled Climate Models or Earth System Models are used. To give trustworthy results, these models must be able to realistically simulate the mechanical and thermodynamic interaction of sea ice with the atmosphere and the ocean, which determine the resulting sea‐ice thickness distribution. While the representation of such air–ice–sea interaction has seen some major advances in the most complex sea‐ice models during the past decade, a number of fundamental processes of air–ice–sea interaction are still only crudely understood and currently not realistically represented in models. This article provides a succinct description of these processes and discusses necessary research directions for their improved representation in models. WIREs Clim Change 2012, 3:509–526. doi: 10.1002/wcc.189 This article is categorized under: Climate Models and Modeling > Model Components