Surface mass balance modelling of the Juneau Icefield highlights the potential for rapid ice loss by the mid-21st century
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Abstract. Plateau icefields are large stores of freshwater, preconditioned to enhanced mass loss due to their gently sloping accumulation areas. Accurately modelling the mass-balance of these icefields is therefore vital for obtaining projections of their future contribution to sea-level rise. Here, we use the COupled Snowpack and Ice surface energy and mass-balance model in PYthon (COSIPY) to simulate the historical and potential future mass balance of the Juneau Icefield, Alaska – a high elevation (>1200 m) plateau icefield. We force the model with dynamically downscaled climate simulations, pertaining to both the past and potential future (RCP 8.5) conditions. The rich dataset of surface mass balance observations of the Juneau Icefield allows us to tune COSIPY, providing confidence in our future predictions and highlighting changes to the icefield between the years 1980 and 2019. Icefield-wide negative mass balances were simulated from the start of the 21st century, as many glaciers transitioned from positive to negative mass-balances. Under RCP8.5, the model simulates increasing negative mass balance across Juneau Icefield, with the entire icefield potentially displaying a negative mass balance by the mid-21st century. This simulated loss of accumulation is driven by increased temperatures and reduced amounts of snowfall, exposing more of the icefield to thinning. Ice thinning is likely to be exacerbated by the exposure of ice to melting across the plateau surface, and prolonged melt may lead to an increase in disconnections, splitting glaciers between their accumulation and ablation areas at icefalls. The similar hypsometry of other high latitude plateau icefields and ice caps may mean that similar processes will act to determine their potential fate in our changing climate.Keywords:
Ice field
Glacier mass balance
Thinning
Abstract On the basis of data from seven years of observations from White Glacier, Axel Heiberg Island and the surrounding tundra, the authors have derived an empirical formula for calculating snow depth on the glacier at various elevations from that on the tundra. This formula allows one to acquire mass balance data without the costly and time‐consuming procedures of glacier traverses.
Glacier mass balance
White (mutation)
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Thinning
Glacier terminus
Glacier mass balance
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The study of glaciers in remote regions improves our understanding of global glacier change. With an area of 149.31 ± 1.84 km2, the Santa Inés Icefield constitutes one of the largest and least studied and explored glaciated areas of Southern Patagonia. We study the extent and glacier variations of the Santa Inés Icefield over the last 75 years, and we generate the most detailed glacier inventory to date of its 24 constituting glaciers. We estimate surface elevation changes between 2000 and 2014 using Shuttle Radar Topography Mission (SRTM) and TanDEM-X digital elevation models. Our results show a generalized trend of retreat, with a glacier area loss of −9.78 ± 1.52 km2 between 1998 and 2020, with annual rate increase from −0.15 ± 0.01 km2 a−1 (1998–2005) to −0.58 ± 0.10 km2 a−1 (2005–2020), and an average thinning of 0.60 ± 0.26 m a−1 (2σ) between 2000 and 2014. No clear correlation was found between retreat or thinning rates and Accumulation Area Ratio (AAR), terminus slope, aspect, or glacier type. While ERA5 reanalysis data shows no significant climatic trends in temperature or precipitation, a small warming trend below our detection record is the most likely cause of the observed retreat and thinning of the Santa Inés Icefield.
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Thinning
Glacier mass balance
Elevation (ballistics)
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The 28 outlet glaciers of the Northern Patagonia Icefield, Chile, with a total contiguous surface area of about 4200 km2, were inventoried in a detailed statistical manner. The San Quintin and San Rafael glaciers, each with an area of about 760 km2, are the two largest. Equilibrium lines are estimated at elevations of 900 to 1350 m, separating the total area into an accumulation area of 2578 km2 and an ablation area of 1550 km2. The variation of 22 major glaciers between 1944/45 and 1985/86 was elucidated and an annual average rate of recession of up to 68 m yr~' was determined. One glacier showed almost no change at all, while the southwestern snout of the Reicher Glacier showed a net advance, although small. A decrease in accumulation in the icefield has caused this general recession. However, the individual variation was probably governed by one of or a combination of the following four factors: (1) orographic situation of the accumulation area, i.e., whether it is located on the leeward (eastern) or windward (western) side; (2) the relative height of the topographic threshold to the icefield surface elevation; (3) the perimeter length, although in a relative sense, of the wasting front of the glacier; and (4) the ratio of the glaction area to the accumulation area of the glacier.
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Glacier mass balance
Accumulation zone
Glacier morphology
Elevation (ballistics)
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Glacier mass balance
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Recent evidence shows that most of Patagonian glaciers are receding rapidly. Due to the lack of in-situ long-term meteorological observations, the understanding of how glaciers are responding to changes in climate over this region is extremely limited and high uncertainties exist in the glacier surface mass balance model parameterizations. This precludes a robust assessment of glacier response to current and projected climate change. An issue of central concern is the accurate estimation of precipitation phase. In this work, we have assessed spatial and temporal patterns in snow accumulation in both the North Patagonia Icefield (NPI) and South Patagonia Icefield (SPI). We used a regional climate model, RegCM4.6 and four Phase Partitioning Methods (PPM) and short-term snow accumulation observations using ultrasonic depth gauges (UDG). Snow accumulation shows that rates are higher on the west side relative to the east side for both Icefields. The values depend on the PPM used and reach a mean difference of 1,500 mm w.e. with some areas reaching differences higher than 3,500 mm w.e. These differences could lead to divergent mass balance estimations, depending on the scheme used to define the snow accumulation. Good agreement is found in comparing UDG observations with modeled data on the plateau area of the SPI during a short time period, however, there are important differences between rates of snow accumulation determined in this work and previous estimations using ice core data at annual scale. Significant positive trends are mainly present in the autumn season on the west side of the SPI, while on the east side, significant negative trends in autumn were observed. Overall, for the rest of the area and during other seasons, no significant changes can be determined. In addition, glaciers with positive and stable elevation and frontal changes determined by previous works, are related to areas where snow accumulation has increased during the period 2000-2015. This suggests that increases in snow accumulation are attenuating the response of some Patagonian glaciers to warming in a regional context of overall glacier retreat.
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Ice core
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The Glacier Research Project in Patagonia with a theme of Characteristics of Recent Glacier Variations in Patagonia, Southern Andes was carried out in the field during the austral summer of 1993/94 : from 9 November to 28 December 1993 at and around Upsala, Ameghino, Moreno and Tyndall glaciers, outlet glaciers from the Southern Patagonia Icefield, and around the Northern Patagonia Icefield. The research topics accomplished include : 1) ice-thickness changes between 1990 and 1993, 2) flow of glaciers, 3) meteorological conditions and heat balance, 4) morphology and thickness of glaciers, 5) landforms around glaciers and Holocene glacier variations, and 6) aerial photographic survey (Northern Patagonia Icefield). As ancillary projects, the following topics were also studied : 7) lake- and glacier-sediments, dendrochronology and glacier fluctuations, 8) recent climatic changes in the Patagonia region. Outline of the project and summaries of the results are presented.
Ice field
Landform
Glacier mass balance
Glacier morphology
Rock glacier
Tidewater glacier cycle
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Global warming has a great impact on the glacier variations and becomes the focus of many scientific researches.The glaciers are more sensitive in the Qinghai Plateau than those at the poles,so it is of significance to research glaciers in the Qangtang Plateau,hinterland of the Tibetan Plateau.Under the influence of the special climate,topography and terrain in the Qangtang Plateau,glaciers center on the mountainous regions,and the main types of glaciers are star and maculosus ice caps or flat-topped.The snowline altitude in the Qangtang Plateau is the highest in China.In this paper,Tupu analysis is performed for glacierized area variation using air photos,relevant photogrammetric maps and the satellite image based on the theories and methods of Geo-Information Tupu since the Little Ice Age(LIA) in the Central and Western Qangtang Plateau.The result clearly reveals that a few glaciers in the plateau are in advance state.However,the glaciers tend to decrease as a whole,glacierized area had decreased from 573.67 km2 to 556.40 km2 by about 3.01% from the LIA to the 2000s.The ablation of glaciers is accelerated over the last decades.However,the glaciers in the plateau are relatively stable as compared with the Puruogangri Ice Field in the same region.Compared with other regions in West China,the glaciers in the study region belong to the extremely-continental type,whose response to climate change is very slow,so the glaciers seem almost more stable in the plateau than in other regions of West China.It is also found that the rapid increasing temperature and decreasing precipitation are mainly responsible for the glacier retreating during the study period.
Glacier morphology
Ice field
Glacier mass balance
Rock glacier
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Ice field
Glacier mass balance
Glacier morphology
Tidewater glacier cycle
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European alpine glaciers lost about 35% of their total area from 1850 until the 1970s, and almost 50% by 2000 (Zemp et al., 2006). With respect to the 1970s area, there was little change until 1985 (-1%) and a strong decrease (-20%) until the year 2000 (Paul et al., 2004). This rapid decline in glacier area has been confirmed by analysis of more recent satellite data (Paul et al., 2007a). This study compared Landsat TM and ASTER imagery from 2003/04 with the earlier data sets and found similar patterns of massive glacier retreat and thinning throughout the entire Alps. Thereby, the thinning was only derived indirectly by recognizing increasing areas with rock outcrops, separation of glacier tongues and disintegrating/collapsing glacier bodies, but is confirmed by direct mass balance measurements as well (Zemp et al., 2005). At several locations pro-glacial lakes have been formed which are partly still growing.
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Thinning
Tidewater glacier cycle
Cirque glacier
Glacier terminus
Glacier morphology
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