An upper limit of 21st century sea-level rise

Despite recent progress in many areas, uncertainty in future sea-level rise remains high. While thermal expansion of the ocean is projected with strong differences between models, the resulting sea-level rise is considered to be gradual and unlikely to contain major surprises. Mountain glaciers store a significant but limited amount of additional water and statistical compensation reduces uncertainty in the overall projection of this century. Thus the largest unknowns are the great ice sheets of Greenland and Antarctica. The dynamics of each of these ice sheets allows for a self-amplifying feedback that might, once triggered, contribute continuously even in the absence of enhanced anthropogenic forcing. Here we estimate an upper limit of sea-level rise for this century based on physical models and plausibility considerations.