Abstract

Abstract. We use a numerical flow line model to simulate the behaviour of the Djankuat Glacier, a World Glacier Monitoring Service reference glacier situated in the North Caucasus (Republic of Kabardino-Balkaria, Russian Federation), in response to past, present and future climate conditions (1752–2100 CE). The model consists of a coupled ice flow–mass balance model that also takes into account the evolution of a supraglacial debris cover. After simulation of the past retreat by applying a dynamic calibration procedure, the model was forced with data for the future period under different scenarios regarding temperature, precipitation and debris input. The main results show that the glacier length and surface area have decreased by ca. 1.4 km (ca. −29.5 %) and ca. 1.6 km2 (−35.2 %) respectively between the initial state in 1752 CE and present-day conditions. Some minor stabilization and/or readvancements of the glacier have occurred, but the general trend shows an almost continuous retreat since the 1850s. Future projections using CMIP5 temperature and precipitation data exhibit a further decline of the glacier. Under constant present-day climate conditions, its length and surface area will further shrink by ca. 30 % by 2100 CE. However, even under the most extreme RCP 8.5 scenario, the glacier will not have disappeared completely by the end of the modelling period. The presence of an increasingly widespread supraglacial debris cover is shown to significantly delay glacier retreat, depending on the interaction between the prevailing climatic conditions, the debris input location, the debris mass flux magnitude and the time of release of debris sources from the surrounding topography.

Highlights

  • A lot of attention has been given to modelling mountain glaciers, in particular due to their worldwide observed shrinkage and important role within the current changing climate (e.g. Shannon et al, 2019; Zekollari et al, 2019; Hock et al, 2019)

  • We use a numerical flow line model to simulate the behaviour of the Djankuat Glacier, a World Glacier Monitoring Service reference glacier situated in the North Caucasus (Republic of Kabardino-Balkaria, Russian Federation), in response to past, present and future climate conditions (1752–2100 CE)

  • We focus on modelling the Djankuat Glacier (North Caucasus, Russian Federation), a WGMS (World Glacier Monitoring Service) reference glacier which has a broad observational network in both space and time

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Summary

Introduction

A lot of attention has been given to modelling mountain glaciers, in particular due to their worldwide observed shrinkage and important role within the current changing climate (e.g. Shannon et al, 2019; Zekollari et al, 2019; Hock et al, 2019). The observed warming trend is a significant matter of concern to scientists and all other people (in)directly involved in the behaviour of these glacial systems, as projected scenarios point towards an even further increase of the global mean temperature in the future, especially if no efficient mitigation strategies are implemented (Stocker et al, 2013; Rasul and Molden, 2019; Hock et al, 2019) Being consistent with this global trend, the accelerated retreat of Caucasian glaciers during the last several decades has been clearly noticed The objectives of this study are to construct and calibrate a coupled ice flow–mass balance–supraglacial debris cover model for the Djankuat Glacier, to reconstruct its front variations and mass balance series since 1752 CE and to simulate the response to future climate change under different scenarios until 2100 CE. The refined debris cover implementation can be used for comparable glacier models in future research

The Djankuat Glacier
Field data
Ice dynamic model
Mass balance model
Debris cover model
Calculation of runoff
Ice dynamics model
Basic sensitivity experiments
Little Ice Age extent of the glacier
Evolution of the glacier from 1752 CE to present
Response to future climate forcing
Impact of supraglacial debris cover on glacier evolution
Findings
Conclusion
Full Text
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