Simulations of changes to Glaciar Zongo, Bolivia (16° S), over the 21st century using a 3-D full-Stokes model and CMIP5 climate projections

Abstract

ABSTRACT. Bolivian glaciers are an essential source of fresh water for the Altiplano, and any changes they may undergo in the near future due to ongoing climate change are of particular concern. Glaciar Zongo, Bolivia, located near the administrative capital La Paz, has been extensively monitored by the GLACIOCLIM observatory in the last two decades. Here we model the glacier dynamics using the 3-D full-Stokes model Elmer/Ice. The model was calibrated and validated over a recent period (1997-2010) using four independent datasets: available observations of surface velocities and surface mass balance were used for calibration, and changes in surface elevation and retreat of the glacier front were used for validation. Over the validation period, model outputs are in good agreement with observations (differences less than a small percentage). The future surface mass balance is assumed to depend on the equilibrium-line altitude (ELA) and temperature changes through the sensitivity of ELA to temperature.

Rapid decline of snow and ice in the tropical Andes – Impacts, uncertainties and challenges ahead

“…Their results indicate a decrease in annual and dry season discharge of 25 and 57% respectively by the end of the 21st century, resulting from a loss of 81% of the glacier volume (in scenario RCP4.5, when compared to reference year 1987), which would render future glacier melt contribution negligible. This reduction is significantly more than the volume loss of only 69% in the higher emission scenario RCP6.0 found by Réveillet et al (2015), highlighting the uncertainty in future projections of glacier loss associated with different methodologies, input parameters and assumptions concerning the different climate scenarios.…”

“…However, this approach neglects any potential future changes in snowfall, which could also affect glacier mass balance. Given the general consensus of a future decrease in precipitation, as portrayed in Urrutia and Vuille (2009), Minvielle and Garreaud (2011) and more recently confirmed by Neukom et al (2015), these projections by Réveillet et al (2015) also have to be considered conservative estimates.…”

“…As discussed in Sections 3.2 and 3.3, the only future glacier change projections including ice dynamics performed in the tropical Andes were done on the highly monitored Zongo glacier, Bolivia (Réveillet et al, 2015;Frans et al, 2015) where ice thickness was measured in-situ. However, even though more in-situ measurements on individual glaciers are needed, it is impossible to directly measure ice thickness on all the individual glaciers, given the cost, logistics, accessibility, etc.…”

“…Réveillet et al (2015) for example used a 3-dimensional full-Stokes model called Elmer-Ice to simulate the evolution of Zongo glacier in the Cordillera Real, Bolivia, for both presentday and future conditions. Implicit in this modeling approach is the assumption that future temperature changes will directly affect the ELA, which is reasonable, given the close relationship between freezing level height and ELA shown above (Fig.…”

Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

“…A variety of recent studies exist for individual glaciers (e.g. Le Meur and Vincent, 2003;Jouvet et al, 2009Jouvet et al, , 2011Aðalgeirsdóttir et al, 2011;Duan et al, 2012;Zekollari et al, 2013Zekollari et al, , 2014Hannesdóttir et al, 2015;Réveillet et al, 2015), but for ice caps such detailed studies are limited (Aðalgeirsdóttir et al, 2005(Aðalgeirsdóttir et al, , 2006Flowers et al, 2005Flowers et al, , 2007Flowers et al, , 2008 Published by Copernicus Publications on behalf of the European Geosciences Union.…”