Projections of Peak Water Timing From the East Rongbuk Glacier, Mt. Everest, Using a Higher-Order Ice Flow Model

In this study, we apply a three-dimensional (3D) thermomechanically coupled higher-order ice flow model to simulate the East Rongbuk Glacier (ERG), Mt. Everest. We first diagnostically investigate its present-day ice dynamic features in 2009 and then prognostically simulate the glacier during the time period 2010-2100. The ice flow model is initialized based on a Robin-type inversion method by conducting six sensitivity experiments relating to glacier thermal boundary conditions. We apply two different surface mass balance parameterizations in the model, and both of them can reproduce the observed ice volume loss (around 0.1 km3) during 2010-2020. We find that ERG is likely to experience maximum meltwater runoff at the year 2030 under the SSP-126 scenario, while under SSP-370 and -585 scenarios, the peak water will both likely occur at around 2060. The ice dynamics may contribute more to ice loss as climate warms in time. The melt of glaciers in High Mountain Asia (HMA) has great impacts on regional water resources and socioeconomy. But it is not an easy task to accurately predict their future changes. The East Rongbuk Glacier (ERG), Mt. Everest, is one of few glaciers in HMA that has relatively rich in situ data for conducting three-dimensional numerical projections. In this study, we first carefully invert basal frictions at the ice-bed interface according to observed ice surface velocities as a model initialization. Then, we drive the model and simulate the changes of ERG from 2010 to 2100. We validate our model by comparing our simulation results to observed ice volume loss during 2010-2020. We find that ERG will reach its maximum meltwater runoff at around 2030 and 2060 for the lower (SSP-126) and higher (SSP-585) emission scenarios, respectively. We conduct diagnostic and prognostic simulations of East Rongbuk Glacier, Mt. Everest The use of Robin inversion method during initialization suggests the presence of temperate basal ice We find East Rongbuk Glacier will likely reach maximum meltwater runoff around the middle of this century