Light-absorbing impurities accelerating glacial melting in southeastern Tibetan Plateau
Hewen NiuShichang KangHailong WangJiankuo DuTao PuGuotao ZhangXixi LuXingguo YanShijin WangXiaofei Shi
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Snowpack
Albedo (alchemy)
Glacier mass balance
Abstract To develop new strategies for global mass-balance monitoring, data for the period 1961–90 have been compiled for 80 glaciers with a variety of mass-balance and morphological parameters. This dataset is significantly larger than that used in previous studies. This allows us to check the mass-balance data for both strong and weak correlations with different glacier parameters. In many cases, the strong correlations suggest new approaches to monitoring glaciers on a global scale. For example, the mass balance at the terminus is strongly correlated with the difference in elevation between the terminus and the glacier’s mean elevation. These easily measured parameters could be particularly useful in assessing maximum ablation and meltwater potential based on altitudes derived from maps and photographs. Good correlations also exist between differences in mass-balance parameters (e.g. net balance minus terminus balance) and several other morphological properties (e.g. elevation range and length). Equally important, the weak correlations demonstrate that some relationships commonly used on individual glaciers are not appropriate when considering global monitoring strategies. For example, the correlation between net mass balance and terminus balance is very poor. Likewise, the correlation between the net mass balance and equilibrium-line altitude is weak, and the correlation between the net mass balance and activity index is almost non-existent. This suggests that although these climatically sensitive parameters may be closely related on individual glaciers, these same relationships are not reliable as tools for monitoring glaciers on a global scale.
Glacier mass balance
Elevation (ballistics)
Meltwater
Glacier terminus
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Abstract Mountain glaciers comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large glacier populations due to remote and rugged geography, variable response of individual glaciers to climate change, and episodic calving losses from tidewater glaciers. In Alaska, we use airborne altimetry from 116 glaciers to estimate a regional mass balance of −75 ± 11 Gt yr −1 (1994–2013). Our glacier sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by glacier type. We find that tidewater glaciers are losing mass at substantially slower rates than other glaciers in Alaska and collectively contribute to only 6% of the regional mass loss.
Glacier mass balance
Tidewater
Tidewater glacier cycle
Rock glacier
Glacier morphology
Glacier ice accumulation
Future sea level
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Snowpack
Albedo (alchemy)
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Abstract. We present a minimal model of the glacier surface mass balance. The model relies solely on monthly precipitation and air temperatures as forcing. We first train the model individually for 15 glaciers with existing mass balance measurements. Based on a cross validation, we present a thorough assessment of the model's performance outside of the training period. The cross validation indicates that our model is robust, and our model's performance compares favorably to that from a less parsimonious model based on seasonal sensitivity characteristics. Then, the model is extended for application on glaciers without existing mass balance measurements, and cross validated using the 15 glaciers above, in order to measure its performance on glaciers not included in the model training. This cross validation indicates that the model retains considerable skill even when applied on glaciers without mass balance measurements. As an exemplary application, the model is then used to reconstruct time series of interannual mass balance variability, covering the past two hundred years, for all glaciers in the European Alps contained in extended format of the world glacier inventory. Based on this reconstruction, we present a spatially detailed attribution of the glaciers' mass balance variability to temperature and precipitation variability.
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Forcing (mathematics)
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Land use changes affect the surface radiative budget and energy balance by changing the surface albedo, which generates radiative forcing, impacting the regional and global climate. To estimate the effect of land use changes on the surface albedo and climate change in a mountainous area with complex terrain, we obtained MODIS data, identified the spatial–temporal characteristics of the surface albedo caused by land use changes, and then calculated the radiative forcing based on solar radiative data and the surface albedo in the Qinling-Daba mountains from 2000 to 2015. The correlation between the land use changes and the radiative forcing was analyzed to explore the climate effects caused by land use changes on a kilometer-grid scale in the Qinling-Daba mountains. Our results show that the primarily land use changes were a decrease in the cultivated land area and an increase in the construction land area, as well as other conversions between six land use types from 2000 to 2015. The land use changes led to significant changes in the surface albedo. Meanwhile, the radiative forcing caused by the land use had different magnitudes, strengths, and occurrence ranges, resulting in both warming and cooling climate change effects.
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Abstract. Despite the great number and variety of glaciers in southern South America, in situ glacier mass-balance records are extremely scarce and glacier–climate relationships are still poorly understood in this region. Here we use the longest (> 35 years) and most complete in situ mass-balance record, available for the Echaurren Norte glacier (ECH) in the Andes at ∼ 33.5° S, to develop a minimal glacier surface mass-balance model that relies on nearby monthly precipitation and air temperature data as forcing. This basic model is able to explain 78 % of the variance in the annual glacier mass-balance record over the 1978–2013 calibration period. An attribution assessment identified precipitation variability as the dominant forcing modulating annual mass balances at ECH, with temperature variations likely playing a secondary role. A regionally averaged series of mean annual streamflow records from both sides of the Andes between ∼ 30 and 37° S is then used to estimate, through simple linear regression, this glacier's annual mass-balance variations since 1909. The reconstruction model captures 68 % of the observed glacier mass-balance variability and shows three periods of sustained positive mass balances embedded in an overall negative trend over the past 105 years. The three periods of sustained positive mass balances (centered in the 1920s–1930s, in the 1980s and in the first decade of the 21st century) coincide with several documented glacier advances in this region. Similar trends observed in other shorter glacier mass-balance series suggest that the Echaurren Norte glacier reconstruction is representative of larger-scale conditions and could be useful for more detailed glaciological, hydrological and climatological assessments in this portion of the Andes.
Glacier mass balance
Forcing (mathematics)
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Abstract To develop new strategies for global mass-balance monitoring, data for the period 1961–90 have been compiled for 80 glaciers with a variety of mass-balance and morphological parameters. This dataset is significantly larger than that used in previous studies. This allows us to check the mass-balance data for both strong and weak correlations with different glacier parameters. In many cases, the strong correlations suggest new approaches to monitoring glaciers on a global scale. For example, the mass balance at the terminus is strongly correlated with the difference in elevation between the terminus and the glacier’s mean elevation. These easily measured parameters could be particularly useful in assessing maximum ablation and meltwater potential based on altitudes derived from maps and photographs. Good correlations also exist between differences in mass-balance parameters (e.g. net balance minus terminus balance) and several other morphological properties (e.g. elevation range and length). Equally important, the weak correlations demonstrate that some relationships commonly used on individual glaciers are not appropriate when considering global monitoring strategies. For example, the correlation between net mass balance and terminus balance is very poor. Likewise, the correlation between the net mass balance and equilibrium-line altitude is weak, and the correlation between the net mass balance and activity index is almost non-existent. This suggests that although these climatically sensitive parameters may be closely related on individual glaciers, these same relationships are not reliable as tools for monitoring glaciers on a global scale.
Glacier mass balance
Elevation (ballistics)
Meltwater
Glacier terminus
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Arctic glaciers comprise a small fraction of the world’s land ice area, but their ongoing mass loss currently represents a large cryospheric contribution to the sea level rise. In the Suntar-Khayata Mountains (SKMs) of northeastern Siberia, in situ measurements of glacier surface mass balance (SMB) are relatively sparse, limiting our understanding of the spatiotemporal patterns of regional mass loss. Here, we present SMB time series for all glaciers in the SKMs, estimated through a glacier SMB model. Our results yielded an average SMB of −0.22 m water equivalents (w.e.) year−1 for the whole region during 1951–2011. We found that 77.4% of these glaciers had a negative mass balance and detected slightly negative mass balance prior to 1991 and significantly rapid mass loss since 1991. The analysis suggests that the rapidly accelerating mass loss was dominated by increased surface melting, while the importance of refreezing in the SMB progressively decreased over time. Projections under two future climate scenarios confirmed the sustained rapid shrinkage of these glaciers. In response to temperature rise, the total present glacier area is likely to decrease by around 50% during the period 2071–2100 under representative concentration pathway 8.5 (RCP8.5).
Glacier mass balance
Glacier ice accumulation
Tidewater glacier cycle
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Glacier mass balance
Accumulation zone
Glacier ice accumulation
Cirque glacier
Ablation zone
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During the expeditions to Mt.Nyainqentanglha in the summer of 1999 and 2007,glacier termini had been surveyed using GPS technology for five glaciers around the mount.Comparing the terminus positions surveyed by the two GPS with those surveyed in 1970 reveal that five glaciers have retreated since 1970.The retreat rate of glacier termini is around 10.0 m·a-1 for the Lanong and Zhadang Glaciers in the northern slopes of the mount and the Panu Glacier in the southern slope during 1970-2007.However,retreat of the Xibu Glacier is dramatic with a rate of 38.9 m·a-1,while a small high-elevation glacier(5O270C0049) in the Panu basin has a low retreat rate of 4.8 m·a-1.A stream was observed in the 1970′s firn basin of the Panu Glacier,indicating that not only the glacier termini are retreating dramatically but also the ablation areas are expanding around the mount.
Glacier mass balance
Tidewater glacier cycle
Glacier terminus
Accumulation zone
Cirque glacier
Glacier morphology
Firn
Glacier ice accumulation
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