In all other places, the formation of stagnant ice relies on low-gradient slopes and is confined to the terminus region of debris-covered glaciers<!–[if supportFields]> XE “glaciers” <![endif]–><!–[if supportFields]><![endif]–><!–[if supportFields]> XE “glacier” <![endif]–><!–[if supportFields]><![endif]–> with shallow gradients. The authors claim that debris-cover—which is almost always a few centimeters thick—leads to a reduction in melt rates and slows down the glacier’s response to climate change. Debris-cover also influences anthropogenic and natural radiative heat transfer. Thus, the authors conclude that topographic factors, which usually vary with terrain, have significant effects on the glacier’s response to climate change and should be accounted for in future mas-balance calculations.
In large areas of the ablation zone in the south of the GrIS, the melting season had started 50 days earlier than the average melting season (measured from 1979 to 2009) and had ended exceptionally late in 2010. While the increase in surface melting can be positively correlated with the increase in near-surface temperatures, recent studies have shown that the melting of the GrIS also depends on the accumulation, radiation, and refreezing and sublimation conditions. The surface mass balance is also strongly correlated with albedo because when melting increases, the grain size of the snow increases and which consequently, decreases the albedo. In this study, the authors used moderate-resolution imaging spectroradiometer (MODIS) albedo product to study anomalies in albedo; they also used data from automatic weather stations and regional surface and energy models to study the surface mass balance anomalies in 2010. They found the largest negative albedo anomalies occurred in August along the south west coast of the ice sheet; they hypothesized that the reduced amount of snowfall, enhanced melting and increased number of bare ice exposure days could have led to the 2010 albedo anomalies. While the early melt season was triggered by the large increase in near-surface temperatures, the reduced accumulation and albedo were more likely to be responsible for the premature bare ice exposure. Thus, the authors inferred that the anomalously warm conditions reduced the accumulation and albedo, which led to the strongly negative surface mass balance of the GrIS in 2010.
The Fourth Assessment Report of the IPCC predicts that the wastage of glaciers and ice caps will lead to a 0.07 to 0.17 m rise in global sea-levels in the twenty first century. Another study found the accelerating rates of mass loss from the glacier mass balance data between 1995 and 2005; the authors of this study used this model to predict a 0.240±0.128 m rise in sea levels, assuming this rate of acceleration is constant. In order to resolve these discrepancies, Radić & Hock studied the volume changes of mountain glaciers and ice caps in 19 spatially resolved glacierized regions. To quantify future volume changes, the authors developed a calibrated mass balance model to applied it to all the glaciers available in the World Glacier Inventory (WGI-XF). According to their multi-model means, glaciers around the world will cause a 0.124±0.037 m rise in sea-level by 2100. Assuming the GCMs are accurate, the authors predict that there will be a global ice volume loss of 0.124±0.037 m SLE (sea level equivalents) by 2100. The volume loss varies considerably from region to region; the smallest loss was predicted to be in Greenland and High Mountain Asia, and the largest in the European Alps and New Zealand. However, these places are not significant contributors to the future rise in sea-level. The glaciers in Arctic Canada, Alaska and Antarctica are estimated to be the largest contributers to the rise in sea-levels. While there are some uncertainties associated with the rise initial setup of the model, this study reveals the main regional contributers to sea-level rise and pinpoint the areas that are most vulnerable to glacier waste. Thus, if warming continues as expected, glaciers will be a large contributer to sea-level rise around the world.