–GlacierMIP is a CliC Activity and part of the WCRP Grand Challenge on Melting Ice and Global Consequence

GlacierMIPFigure2020(a) Number of Randolph Glacier Inventory (RGI) regions modeled by each glacier model. (b–d) Number of ensemble members for each (b) glacier model, (c) general circulation models (GCM), and (d) Representative Concentration Pathways (RCP) scenario. Colors to identify models or scenarios are used consistently throughout the paper.

Citation: Marzeion, B., Hock, R., Anderson, B., Bliss, A., Champollion, N., Fujita, K., et al. (2020). Partitioning the uncertainty of ensemble projections of global glacier mass change  Earth’s Future. 8, e2019EF001470. https://doi.org/10.1029/2019EF001470

Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. This paper presents an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation models and four Representative Concentration Pathways (RCPs) as boundary conditions. The authors partition the total uncertainty into the individual contributions caused by glacier models, general circulation models, RCPs, and natural variability. They find that emission scenario uncertainty is growing throughout the 21st century and is the largest source of uncertainty by 2100. The relative importance of glacier model uncertainty decreases over time, but it is the greatest source of uncertainty until the middle of this century. The projection uncertainty associated with natural variability is small on the global scale but can be large on regional scales. The projected global mass loss by 2100 relative to 2015 (79 ± 56 mm sea level equivalent for RCP2.6, 159 ± 86 mm sea level equivalent for RCP8.5) is lower than, but well within, the uncertainty range of previous projections.