Global glaciological models: a new stage in the development of methods for predicting glacier evolution. Part 1. General approach and model architecture

Abstract

For several decades, mathematical models of mountain glaciers and ice sheets have been used to study the dynamics of the cryosphere. In recent years, a new step in glaciological modeling has made possible to recon- struct processes in mountain-glacial systems both regionally and globally. The proposed review analyses rea- sons to use this possibility for global glaciological models, key assumptions and methods, general approaches and differences between individual models. Global glacier modeling is a rapidly developing field. This became possible only after the data on all glaciers of the world appeared in the Randolph Glacier Inventory in 2012. The ice thickness inversion procedures discussed in this review made it possible to calculate the initial volume and geometry of glaciers. Methods of varying complexity were used to regionalize global climate data and cal- culate glacier mass balance. Modeling the dynamics of glaciers required the adaptation of simplified schemes to represent the fluidity of ice (or the flow of ice). To date, only two global glacier models contain ice dynamics calculations based on Glenn's law and the diffusion equation: OGGM and GloGEMflow. Simulation results are subject to uncertainties due to input errors, climate predictions, model approximations, and calibration proce- dures. A new stage in the development of methods opens up opportunities to use a number of new directions in the study of the mechanisms that control the evolution of glaciation, depending on the implementation of a particular climatic scenario. Global glacier models make possible to build glaciological projections, calculate potential changes in the regime of glacial runoff, as well as assess risks and predict the occurrence of dangerous processes caused by changes in glaciation parameters, such as mudflows, landslides, and glacial lake outbursts.