Limits...
Temporal constraints on future accumulation-area loss of a major Arctic ice cap due to climate change (Vestfonna, Svalbard).

Möller M, Schneider C - Sci Rep (2015)

Bottom Line: Results indicate strongly decreasing climatic mass balances over the 21(st) century for all RCPs considered.Glacier-wide mass-balance rates will drop down to -4 m a(-1) w.e. (water equivalent) at a maximum.The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Geography, RWTH Aachen University, Wüllnerstraβe 5b, 52056 Aachen, Germany [2] Departamento Matemática Aplicada, E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid, Avenida Complutense 30, 28040 Madrid, Spain.

ABSTRACT
Arctic glaciers and ice caps are major contributors to past, present and future sea-level fluctuations. Continued global warming may eventually lead to the equilibrium line altitudes of these ice masses rising above their highest points, triggering unstoppable downwasting. This may feed future sea-level rise considerably. We here present projections for the timing of equilibrium-line loss at the major Arctic ice cap Vestfonna, Svalbard. The projections are based on spatially distributed climatic mass balance modelling driven by the outputs of multiple climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) forced by the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5. Results indicate strongly decreasing climatic mass balances over the 21(st) century for all RCPs considered. Glacier-wide mass-balance rates will drop down to -4 m a(-1) w.e. (water equivalent) at a maximum. The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario.

No MeSH data available.


Related in: MedlinePlus

Variability of the relevance of refreezing processes for the climatic mass balance of Vestfonna over the 21st century.The line graphs show annual values of the fraction of refreezing sums in the overall mass gain of Vestfonna (a) and of the fraction of meltwater that refreezes (b). Data represent the ensemble means of the RCPs.
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f4: Variability of the relevance of refreezing processes for the climatic mass balance of Vestfonna over the 21st century.The line graphs show annual values of the fraction of refreezing sums in the overall mass gain of Vestfonna (a) and of the fraction of meltwater that refreezes (b). Data represent the ensemble means of the RCPs.

Mentions: The evolution of the CMB of Vestfonna is largely controlled by the annual ablation rates, which increase continuously and substantially over the 21st century (Fig. 3). Annual accumulation, in contrast, only increases over the first decades of the modelling period. All ensemble means start continuous decreases by no later than 2031 that persist over the entire century. When following the RCP 8.5 annual accumulation is even ~19% lower at the end of the century than at the beginning. Correspondingly, liquid precipitation (rainfall) increases strongly and continuously over the entire modelling period (Fig. 3). As a deduced value that is dependent on the three mass balance-relevant quantities ablation, accumulation and rainfall, refreezing shows the most complex evolution over the 21st century (Fig. 3). Within all scenarios strongly increasing annual refreezing sums are predicted for the first two decades. In the RCP 8.5 projections the refreezing sums even increase by almost 20% within the first decade and the increase continues at reduced rates until the early 2040s. For the other three scenarios the increase of refreezing continues until the early 2090s. After reaching a maximum the annual refreezing decreases in all scenarios until the end of the century. The annual refreezing in RCP 8.5 even drops back to values similar to those at the beginning of the modelling period. However, even if the absolute amounts of refreezing tend to decrease over the 21st century, the relative importance of refreezing for CMB does not (Fig. 4). Whereas refreezing contributes around 40% to the absolute annual mass gain of Vestfonna at the beginning of the modelling period, the projections indicate that this share increases slightly and continuously to between 43 and 47% at the end of the century.


Temporal constraints on future accumulation-area loss of a major Arctic ice cap due to climate change (Vestfonna, Svalbard).

Möller M, Schneider C - Sci Rep (2015)

Variability of the relevance of refreezing processes for the climatic mass balance of Vestfonna over the 21st century.The line graphs show annual values of the fraction of refreezing sums in the overall mass gain of Vestfonna (a) and of the fraction of meltwater that refreezes (b). Data represent the ensemble means of the RCPs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308701&req=5

f4: Variability of the relevance of refreezing processes for the climatic mass balance of Vestfonna over the 21st century.The line graphs show annual values of the fraction of refreezing sums in the overall mass gain of Vestfonna (a) and of the fraction of meltwater that refreezes (b). Data represent the ensemble means of the RCPs.
Mentions: The evolution of the CMB of Vestfonna is largely controlled by the annual ablation rates, which increase continuously and substantially over the 21st century (Fig. 3). Annual accumulation, in contrast, only increases over the first decades of the modelling period. All ensemble means start continuous decreases by no later than 2031 that persist over the entire century. When following the RCP 8.5 annual accumulation is even ~19% lower at the end of the century than at the beginning. Correspondingly, liquid precipitation (rainfall) increases strongly and continuously over the entire modelling period (Fig. 3). As a deduced value that is dependent on the three mass balance-relevant quantities ablation, accumulation and rainfall, refreezing shows the most complex evolution over the 21st century (Fig. 3). Within all scenarios strongly increasing annual refreezing sums are predicted for the first two decades. In the RCP 8.5 projections the refreezing sums even increase by almost 20% within the first decade and the increase continues at reduced rates until the early 2040s. For the other three scenarios the increase of refreezing continues until the early 2090s. After reaching a maximum the annual refreezing decreases in all scenarios until the end of the century. The annual refreezing in RCP 8.5 even drops back to values similar to those at the beginning of the modelling period. However, even if the absolute amounts of refreezing tend to decrease over the 21st century, the relative importance of refreezing for CMB does not (Fig. 4). Whereas refreezing contributes around 40% to the absolute annual mass gain of Vestfonna at the beginning of the modelling period, the projections indicate that this share increases slightly and continuously to between 43 and 47% at the end of the century.

Bottom Line: Results indicate strongly decreasing climatic mass balances over the 21(st) century for all RCPs considered.Glacier-wide mass-balance rates will drop down to -4 m a(-1) w.e. (water equivalent) at a maximum.The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Geography, RWTH Aachen University, Wüllnerstraβe 5b, 52056 Aachen, Germany [2] Departamento Matemática Aplicada, E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid, Avenida Complutense 30, 28040 Madrid, Spain.

ABSTRACT
Arctic glaciers and ice caps are major contributors to past, present and future sea-level fluctuations. Continued global warming may eventually lead to the equilibrium line altitudes of these ice masses rising above their highest points, triggering unstoppable downwasting. This may feed future sea-level rise considerably. We here present projections for the timing of equilibrium-line loss at the major Arctic ice cap Vestfonna, Svalbard. The projections are based on spatially distributed climatic mass balance modelling driven by the outputs of multiple climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) forced by the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0 and 8.5. Results indicate strongly decreasing climatic mass balances over the 21(st) century for all RCPs considered. Glacier-wide mass-balance rates will drop down to -4 m a(-1) w.e. (water equivalent) at a maximum. The date at which the equilibrium line rises above the summit of Vestfonna (630 m above sea level) is calculated to range between 2040 and 2150, depending on scenario.

No MeSH data available.


Related in: MedlinePlus