scholarly journals Modelling the mass budget and future evolution of Tunabreen, central Spitsbergen

2021 ◽  
Author(s):  
Johannes Oerlemans ◽  
Jack Kohler ◽  
Adrian Luckman
Keyword(s):  
Response Times ◽  
Equilibrium Line Altitude ◽  
Future Evolution ◽  
State Response ◽  
The Past ◽  
Glacier Length ◽  
Model Geometry ◽  
Calving Rate ◽  
Meteorological Observations

Abstract. Tunabreen is a 26-km long tidewater glacier. It is the most frequently surging glacier in Svalbard, with four documented surges in the past hundred years. We have modelled the evolution of this glacier with a Minimal Glacier Model (MGM), in which ice mechanics, calving and surging are parameterized. The model geometry consists of a flow band to which three tributaries supply mass. The calving rate is set to the mean observed value for the period 2012–2019, and kept constant. For the past 120 years, a smooth Equilibrium Line Altitude (ELA) history is reconstructed by finding the best possible match between observed and simulated glacier length. There is a modest correlation between this ELA history and meteorological observations from Longyearbyen. The simulated glacier retreat is in good agreement with observations. Runs with and without surging show that the effect of surging on the long term glacier evolution is limited. Due to the low surface slope and associated strong height -mass balance feedback, Tunabreen is very sensitive to changes in ELA. For a constant future ELA equal to the reconstructed value for 2020, the glacier front will retreat by 8 km during the coming hundred years. For an increase of the ELA of 2 m per year, the retreat is projected to be 13 km and Tunabreen becomes a land-based glacier around 2100. The calving rate is an important parameter: increasing its value by 50 % has about the same effect as a 50 m increase in the ELA, the corresponding equilibrium glacier length being 18 km (as compared to 25.8 km in the reference state). Response times vary from 150 to 400 years, depending on the forcing and on the state of the glacier (tidewater or land-based).

scholarly journals Evolution of Rhonegletscher, Switzerland, over the past 125 years and in the future: application of an improved flowline model

2007 ◽  
Vol 46 ◽  
pp. 268-274 ◽  
Author(s):  
Shin Sugiyama ◽  
Andreas Bauder ◽  
Conradin Zahno ◽  
Martin Funk
Keyword(s):  
Mass Balance ◽  
Aerial Photographs ◽  
Future Application ◽  
Equilibrium Line Altitude ◽  
Future Evolution ◽  
The Past ◽  
Temperature And Precipitation ◽  
The Future ◽  
Shape Effects ◽  
Precipitation Records

AbstractTo study the past and future evolution of Rhonegletscher, Switzerland, a flowline model was developed to include valley shape effects more accurately than conventional flowband models. In the model, the ice flux at a gridpoint was computed by a two-dimensional ice-flow model applied to the valley cross-section. The results suggested the underestimation of the accumulation area, which seems to be a general problem of flowline modelling arising from the model’s one-dimensional nature. The corrected mass balance was coupled with the equilibrium-line altitude (ELA) change, which was reconstructed for the period 1878–2003 from temperature and precipitation records, to run the model for the past 125 years. The model satisfactorily reproduced both changes in the terminus position and the total ice volume derived from digital elevation models of the surface obtained by analyses of old maps and aerial photographs. This showed the model’s potential to simulate glacier evolution when an accurate mass balance could be determined. The future evolution of Rhonegletscher was evaluated with three mass-balance conditions: the mean for the period 1994–2003, and the most negative (2003) and positive (1978) mass-balance values for the past 50 years. The model predicted volume changes of –18%, –58% and +38% after 50 years for the three conditions, respectively.

scholarly journals A minimal model of a tidewater glacier

2005 ◽  
Vol 42 ◽  
pp. 1-6 ◽  
Author(s):  
J. Oerlemans ◽  
F.M. Nick
Keyword(s):  
Velocity Field ◽  
Water Depth ◽  
Ice Thickness ◽  
Global Dynamics ◽  
Equilibrium Line Altitude ◽  
Glacier Terminus ◽  
Tidewater Glacier ◽  
Glacier Length ◽  
Parameterized Model ◽  
Calving Rate

AbstractWe propose a simple, highly parameterized model of a tidewater glacier. The mean ice thickness and the ice thickness at the glacier front are parameterized in terms of glacier length and, when the glacier is calving, water depth. We use a linear relation between calving rate and water depth. The change in glacier length is determined by the total change in the mass budget (surface balance and calving flux), but not by the details of the glacier profile and the related velocity field. We show that this may still yield relatively rapid rates of retreat for an idealized bed geometry with a smooth overdeepening. The model is able to simulate the full cycle of ice-free conditions, glacier terminus on land, tidewater glaciers terminus, and backwards. We study two cases: (i) a glacier with a specific balance (accumulation) that is spatially uniform, and (ii) a glacier in a warmer climate with the specific balance being a linear function of altitude. Equilibrium states exhibit a double branching with respect to the climatic forcing (equilibrium-line altitude). One bifurcation is related to the dependence of the calving process on the bed profile; the other bifurcation is due to the height–mass-balance feedback. We discuss the structure of the solution diagram for different values of the calving-rate parameter. The model results are similar to those of Vieli and others (2001), who combined a fairly sophisticated two-dimensional (vertical plane) numerical ice-flow model with the modified flotation criterion suggested by Van der Veen (1996). With regard to the global dynamics of a tidewater glacier, we conclude that the details of the glacier profile or velocity field are less significant than the bed profile and the relation between the water depth and the calving rate.

scholarly journals Numerical modelling of past retreat and future evolution of Chhota Shigri glacier in Western Indian Himalaya

2017 ◽  
Vol 58 (75pt2) ◽  
pp. 136-144 ◽  
Author(s):  
Prateek Gantayat ◽  
Anil V. Kulkarni ◽  
J. Srinivasan ◽  
Maurice J Schmeits
Keyword(s):  
Indian Himalaya ◽  
Local Climate ◽  
Future Evolution ◽  
The Past ◽  
Chhota Shigri Glacier ◽  
Climatic Scenarios ◽  
History Of ◽  
Glacier Length ◽  
Almost All ◽  
The Relationship

ABSTRACT The history of glacier length fluctuations serves as a reliable indicator of the past climate. In this paper, a numerical flowline model has been used to study the relationship between length variations of Chhota Shigri glacier and local climate since 1876. The simulated front positions of Chhota Shigri glacier are in agreement with those observed. After a successful simulation of the past retreat, the model was also used to predict future evolution of the glacier for the next 100 years under different climatic scenarios. These simulations indicate that the Chhota Shigri glacier may lose ~90% of its present volume by 2100 if the local temperature increases by 2.4 K, and for a temperature rise of 5.5 K, the glacier loses almost all its volume.

scholarly journals Modelling the late Holocene and future evolution of Monacobreen, northern Spitsbergen

2018 ◽  
Vol 12 (9) ◽  
pp. 3001-3015 ◽  
Author(s):  
Johannes Oerlemans
Keyword(s):  
Late Holocene ◽  
Meteorological Data ◽  
Ice Age ◽  
Future Climate Change ◽  
Equilibrium Line Altitude ◽  
Climatic Forcing ◽  
Future Evolution ◽  
Front Position ◽  
Tidewater Glacier ◽  
Glacier Length

Abstract. Monacobreen is a 40 km long surge-type tidewater glacier in northern Spitsbergen. During 1991–1997 Monacobreen surged and advanced by about 2 km, but the front did not reach the maximum Little Ice Age (LIA) stand. Since 1997 the glacier front is retreating at a fast rate (∼125 m a−1). The questions addressed in this study are as follows: (1) Can the late Holocene behaviour of Monacobreen be understood in terms of climatic forcing?, and (2) What will be the likely evolution of this glacier for different scenarios of future climate change? Monacobreen is modelled with a minimal glacier model, including a parameterization of the calving process as well as the effect of surges. The model is driven by an equilibrium-line altitude (ELA) history derived from lake sediments of a nearby glacier catchment in combination with meteorological data from 1899 onwards. The simulated glacier length is in good agreement with the observations: the maximum LIA stand, the front position at the end of the surge, and the 2.5 km retreat after the surge (1997–2016) are well reproduced (the mean difference between observed and simulated glacier length being 6 % when scaled with the total retreat during 1900–2016). The effect of surging is limited. Directly after a surge the initiated mass balance perturbation due to a lower mean surface elevation is about -0.13mw.e.a-1, which only has a small effect on the long-term evolution of the glacier. The simulation suggests that the major growth of Monacobreen after the Holocene climatic optimum started around 1500 BCE. Monacobreen became a tidewater glacier around 500 BCE and reached a size comparable to the present state around 500 CE. For the mid-B2 scenario (IPCC, 2013), which corresponds to a ∼2ma-1 rise of the ELA, the model predicts a volume loss of 20 % to 30 % by the year 2100 (relative to the 2017 volume). For a ∼4ma-1 rise in the ELA this is 30 % to 40 %. However, much of the response to 21st century warming will still come after 2100.

scholarly journals Modelling the late-Holocene and future evolution of Monacobreen, northern Spitsbergen

2018 ◽  
Author(s):  
Johannes Oerlemans
Keyword(s):  
Meteorological Data ◽  
Surface Profile ◽  
Reference Value ◽  
Future Evolution ◽  
Front Position ◽  
Tidewater Glacier ◽  
Glacier Length ◽  
Modest Effect ◽  
Good Agreement

Abstract. Monacobreen is a 40 km long surge-type tidewater glacier in northen Spitsbergen. The glacier flows down from Isachsenfonna (~1000 m a.s.l.), and drains an area of about 400 km2. The longitudinal surface profile is smooth and the mean slope is small (0.027). During 1991–1997 Monacobreen surged and advanced by about 2 km, but the front did not reach the maximum LIA stand. Since 1997 the glacier front has receded over a distance of 2.5 km. In this study Monacobreen is modelled with a Minimal Glacier Model, including a parameterization of the calving process as well as the effect of surges. The glacier is modelled as a 5 km wide flowband, to which 10 tributary glaciers and basins supply mass when they have a positive budget. The bed profile is not known, but supposed to be similar to that of Kronebreen, which flows from the same plateau into the opposite direction. The model is driven by a well-constrained ELA history derived from lake sediments of a nearby glacier catchment (Røthe et al., 2015), in combination with meteorological data from 1899 onwards. The model is calibrated by optimising a surge parameter and the reference value of the ELA. The simulated glacier length is in good agreement with the observations: the maximum LIA stand, the front position at the end of the surge, and the 2.5 km retreat after the surge (1997–2016) are accurately reproduced. The effect of surging, with a surge cycle of 100 years, appears to be limited. Directly after a surge the initiated mass-balance pertubation due to a lower mean surface elevation is about −0.16 m w.e./yr. This only has a modest effect on the long-term evolution of the glacier. The simulation suggests that the major growth of Monacobreen after the Holocene Climatic Optimum started around 1500 BC. Monacobreen became a tidewater glacier around 500 BC, and reached a size comparable to the present state around 500 AD. After that the length of the glacier has fluctuated within a range of about 5 km. The e-folding time scale appears to be of the order of 350 years. For the mid-B2 scenario (IPCC, 2013), which corresponds to a ~2 m/yr rise of the ELA, the model predicts a volume loss of 20 to 30 % by the year 2100 (relative to the 2017 volume). For a 4 m/yr rise in the ELA this is 30 to 40 %. However, much of the response to 21st century warming will come after 2100.

scholarly journals Modelling the Vadret da Tschierva, Switzerland: calibration with the historical length record and future response to climate change

2021 ◽  
pp. 1-10
Author(s):  
Johannes Oerlemans ◽  
Felix Keller
Keyword(s):  
Climate Model ◽  
Control Method ◽  
Coupled Model ◽  
Swiss Alps ◽  
Main Stream ◽  
Future Evolution ◽  
Intercomparison Project ◽  
Glacier Length ◽  
Climate Model Output ◽  
Meteorological Observations

Abstract The Vadret da Tschierva (Vd Tschierva) is a 4 km long glacier in the Swiss Alps spanning an altitude range of 2400–4049 m a.s.l. Length observations since 1855 show steady retreat interrupted by a period of advance from 1965 until 1985. The total retreat is ~2200 m (period 1855–2018). We have studied the Vd Tschierva with a flowline model, combined with ‘buckets’ that represent steep hanging glaciers and ice-free rock faces delivering mass to the main stream. The model is calibrated by a control method, in which an ELA history is objectively determined by finding the best match between observed and simulated glacier length. There is a modest correlation between the reconstructed ELA and an ELA record based on meteorological observations at Segl-Maria (only 8 km away from the glacier). It is difficult to reproduce the observed length record when the glacier model is driven by climate model output (Coupled Model Intercomparison Project 5). We have calculated the future evolution of the Vd Tschierva for different rates of ELA rise. For a constant rise of 4 ${\rm m\;}{\rm a}^{ \hbox{-} 1}$ , we predict that the glacier length will change from the current 3.2 km to ~1.7 km in the year 2100.

Enabling Community Well-being Self-Monitoring in the Context of Mining: The Naskapi Nation of Kawawachikamach

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Robert Klinck ◽  
Ben Bradshaw ◽  
Ruby Sandy ◽  
Silas Nabinacaboo ◽  
Mannie Mameanskum ◽  
...  
Keyword(s):  
Indigenous Peoples ◽  
Well Being ◽  
Aboriginal Community ◽  
Self Monitoring ◽  
Community Engaged Research ◽  
The Past ◽  
Mineral Development ◽  
Iron Deposits ◽  
Term Monitoring

The Naskapi Nation of Kawawachikamach is an Aboriginal community located in northern Quebec near the Labrador Border. Given the region’s rich iron deposits, the Naskapi Nation has considerable experience with major mineral development, first in the 1950s to the 1980s, and again in the past decade as companies implement plans for further extraction. This has raised concerns regarding a range of environmental and socio-economic impacts that may be caused by renewed development. These concerns have led to an interest among the Naskapi to develop a means to track community well-being over time using indicators of their own design. Exemplifying community-engaged research, this paper describes the beginning development of such a tool in fall 2012—the creation of a baseline of community well-being against which mining-induced change can be identified. Its development owes much to the remarkable and sustained contribution of many key members of the Naskapi Nation. If on-going surveying is completed based on the chosen indicators, the Nation will be better positioned to recognize shifts in its well-being and to communicate these shifts to its partners. In addition, long-term monitoring will allow the Naskapi Nation to contribute to more universal understanding of the impacts of mining for Indigenous peoples.

Courting the Youth Vote in 2008: The Obama Effect

2009 ◽  
Vol 5 ◽  
Author(s):  
Lindsey C Bohl
Keyword(s):  
Presidential Elections ◽  
Voter Registration ◽  
The Internet ◽  
The Past ◽  
Several Variables ◽  
High Turnout ◽  
Short And Long Term ◽  
Use Of The Internet ◽  
Youth Vote

This paper examines a few of the numerous factors that may have led to increased youth turnout in 2008 Election. First, theories of voter behavior and turnout are related to courting the youth vote. Several variables that are perceived to affect youth turnout such as party polarization, perceived candidate difference, voter registration, effective campaigning and mobilization, and use of the Internet, are examined. Over the past 40 years, presidential elections have failed to engage the majority of young citizens (ages 18-29) to the point that they became inclined to participate. This trend began to reverse starting in 2000 Election and the youth turnout reached its peak in 2008. While both short and long-term factors played a significant role in recent elections, high turnout among youth voters in 2008 can be largely attributed to the Obama candidacy and campaign, which mobilized young citizens in unprecedented ways.

Impact of FII’s and FDI’s on Indian Stock Market

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Dr. Kamlesh Kumar Shukla
Keyword(s):  
Stock Market ◽  
Financial Markets ◽  
Global Economy ◽  
Short Term ◽  
Earnings Growth ◽  
The Past ◽  
Bull Market ◽  
Indian Stock Market

FIIs are companies registered outside India. In the past four years there has been more than $41 trillion worth of FII funds invested in India. This has been one of the major reasons on the bull market witnessing unprecedented growth with the BSE Sensex rising 221% in absolute terms in this span. The present downfall of the market too is influenced as these FIIs are taking out some of their invested money. Though there is a lot of value in this market and fundamentally there is a lot of upside in it. For long-term value investors, there’s little because for worry but short term traders are adversely getting affected by the role of FIIs are playing at the present. Investors should not panic and should remain invested in sectors where underlying earnings growth has little to do with financial markets or global economy.

Chinese Medicine Protein and Peptide in Gene and Cell Therapy

2019 ◽  
Vol 20 (3) ◽  
pp. 251-264 ◽  
Author(s):  
Yinlu Feng ◽  
Zifei Yin ◽  
Daniel Zhang ◽  
Arun Srivastava ◽  
Chen Ling
Keyword(s):  
Chinese Medicine ◽  
Cell Therapy ◽  
Future Research ◽  
The Past ◽  
Promising Strategy ◽  
Wide Range ◽  
New Directions ◽  
Gene And Cell Therapy ◽  
Proteins And Peptides

The success of gene and cell therapy in clinic during the past two decades as well as our expanding ability to manipulate these biomaterials are leading to new therapeutic options for a wide range of inherited and acquired diseases. Combining conventional therapies with this emerging field is a promising strategy to treat those previously-thought untreatable diseases. Traditional Chinese medicine (TCM) has evolved for thousands of years in China and still plays an important role in human health. As part of the active ingredients of TCM, proteins and peptides have attracted long-term enthusiasm of researchers. More recently, they have been utilized in gene and cell therapy, resulting in promising novel strategies to treat both cancer and non-cancer diseases. This manuscript presents a critical review on this field, accompanied with perspectives on the challenges and new directions for future research in this emerging frontier.

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