Greenland ice-sheet contribution to sea-level rise buffered by meltwater storage in firn

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Abstract

Surface melt on the Greenland ice sheet has shown increasing trends in areal extent and duration since the beginning of the satellite era1,2,3. Records for melt were broken in 20054, 20075, 20106 and 20127. Much of the increased surface melt is occurring in the percolation zone, a region of the accumulation area that is perennially covered by snow and firn (partly compacted snow). The fate of melt water in the percolation zone is poorly constrained: some may travel away from its point of origin and eventually influence the ice sheet’s flow dynamics and mass balance and the global sea level, whereas some may simply infiltrate into cold snow or firn and refreeze with none of these effects. Here we quantify the existing water storage capacity of the percolation zone of the Greenland ice sheet and show the potential for hundreds of gigatonnes of meltwater storage. We collected in situ observations of firn structure and meltwater retention along a roughly 85-kilometre-long transect of the melting accumulation area. Our data show that repeated infiltration events in which melt water penetrates deeply (more than 10 metres) eventually fill all pore space with water. As future surface melt intensifies under Arctic warming, a fraction of melt water that would otherwise contribute to sea-level rise will fill existing pore space of the percolation zone. We estimate the lower and upper bounds of this storage sink to be 322 ± 44 gigatonnes and  gigatonnes, respectively. Furthermore, we find that decades are required to fill this pore space under a range of plausible future climate conditions. Hence, routing of surface melt water into filling the pore space of the firn column will delay expansion of the area contributing to sea-level rise, although once the pore space is filled it cannot quickly be regenerated.

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Figure 1: Greenland melt and study location.
Figure 2: Firn–ice content.
Figure 3: Capacity and fill depth at sites along study transect.
Figure 4: Pore space fill time under various future climate scenarios.

References

  1. 1

    Mote, T. L. Greenland surface melt trends 1973–2007: evidence of a large increase in 2007. Geophys. Res. Lett. 34, L22507 (2007)

  2. 2

    Tedesco, M. Snowmelt detection over the Greenland ice sheet from SSM/I brightness temperature daily variations. Geophys. Res. Lett. 34, L02504 (2007)

  3. 3

    Fettweis, X., Tedesco, M., van den Broeke, M. & Ettema, J. Melting trends over the Greenland ice sheet (1958–2009) from spaceborne microwave data and regional climate models. Cryosphere 5, 359–375 (2011)

  4. 4

    Hanna, E. et al. Increased runoff from melt from the Greenland Ice Sheet: a response to global warming. J. Clim. 21, 331–341 (2008)

  5. 5

    Tedesco, M. A new record in 2007 for melting in Greenland. Eos Trans. AGU 88, 383 (2007)

  6. 6

    Box, J. E. et al. in State of the Climate in 2010 (eds Blunden, J., Arndt, D. S. & Baringer, M. O. ) 156–160 (AMS, 2011)

  7. 7

    Cole, S. Satellites See Unprecedented Greenland Ice Sheet Surface Melt. NASA News Release 12–249. (2012)

  8. 8

    van Den Broeke, M. et al. Partitioning recent Greenland mass loss. Science 326, 984–986 (2009)

  9. 9

    Huybrechts, P. et al. Response of the Greenland and Antarctic Ice Sheets to multi-millennial greenhouse warming in the earth system model of intermediate complexity LOVECLIM. Surv. Geophys. 32, 397–416 (2011)

  10. 10

    Vizcaíno, M., Mikolajewicz, U., Jungclaus, J. & Schurgers, G. Climate modification by future ice sheet changes and consequences for ice sheet mass balance. Clim. Dyn. 34, 301–324 (2010)

  11. 11

    Pfeffer, W. T., Meier, M. F. & Illangasekare, T. H. Retention of Greenland runoff by refreezing: implications for projected future sea level change. J. Geophys. Res. 96, 22117–22124 (1991)

  12. 12

    Janssens, I. & Huybrechts, P. The treatment of meltwater retention in mass-balance parameterizations of the Greenland ice sheet. Ann. Glaciol. 31, 133–140 (2000)

  13. 13

    Braithwaite, R. J., Laternser, M. & Pfeffer, W. T. Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland. J. Glaciol. 40, 477–485 (1994)

  14. 14

    Müller, F. Zonation in the accumulation area of the glaciers of Axel Heiberg Island, NWT, Canada. J. Glaciol. 4, 302–313 (1962)

  15. 15

    Marsh, P. & Woo, M. K. Wetting front advance and freezing of meltwater within a snow cover: 1. Observations in the Canadian Arctic. Wat. Resour. Res. 20, 1853–1864 (1984)

  16. 16

    Reijmer, C., van den Broeke, M., Fettweis, X., Ettema, J. & Stap, L. Refreezing on the Greenland ice sheet: a comparison of parameterizations. Cryosphere 6, 743–762 (2012)

  17. 17

    Fischer, H., Wagenbach, D., Laternser, M. & Haeberli, W. Glacio-meteorological and isotopic studies along the EGIG line, central Greenland. J. Glaciol. 41, 515–527 (1995)

  18. 18

    Abdalati, W. & Steffen, K. Greenland ice sheet melt extent: 1979–1999. J. Geophys. Res. 106, 33983–33988 (2001)

  19. 19

    Bales, R. C., McConnell, J. R., Mosley-Thompson, E. & Csatho, B. Accumulation over the Greenland ice sheet from historical and recent records. J. Geophys. Res. 106, 33813–33825 (2001)

  20. 20

    Burgess, E. W. et al. A spatially calibrated model of annual accumulation rate on the Greenland Ice Sheet (1958–2007). J. Geophys. Res. 115, F02004 (2010)

  21. 21

    McConnell, J. R., Mosley-Thompson, E., Bromwich, D. H., Bales, R. C. & Kyne, J. D. Interannual variations of snow accumulation on the Greenland Ice Sheet (1985–1996): new observations versus model predictions. J. Geophys. Res. 105, 4039–4046 (2000)

  22. 22

    Humphrey, N. F., Harper, J. T. & Pfeffer, W. T. Thermal tracking of meltwater retention in Greenland’s accumulation area. J. Geophys. Res. 117, F01010 (2012)

  23. 23

    Brown, J., Harper, J., Pfeffer, W. T., Humphrey, N. & Bradford, J. High-resolution study of layering within the percolation and soaked facies of the Greenland ice sheet. Ann. Glaciol. 52, 35–42 (2011)

  24. 24

    Harper, J. T., Humphrey, N. F., Pfeffer, W. T. & Brown, J. Firn stratigraphy and temperature to 10 m depth in the percolation zone of Western Greenland, 2007–2009. INSTAAR Occas. Pap. 60. (2011)

  25. 25

    Brown, J. et al. Georadar-derived estimates of firn density in the percolation zone, western Greenland ice sheet. J. Geophys. Res. 117, F01011 (2012)

  26. 26

    Herron, M. M. & Langway, C. C., Jr Firn densification: an empirical model. J. Glaciol. 25, 373–385 (1980)

  27. 27

    Alley, R. B., Clark, P. U., Huybrechts, P. & Joughin, I. Ice-sheet and sea-level changes. Science 310, 456–460 (2005)

  28. 28

    Fettweis, X., Belleflamme, A., Erpicum, M., Franco, B. & Nicolay, S. in Climate Change – Geophysical Foundations and Ecological Effects (eds Blanco, J. & Kheradmand, H. ) 503–520 (Intech, 2011)

  29. 29

    Box, J. E., Bromwich, D. H. & Bai, L. S. Greenland ice sheet surface mass balance 1991–2000: application of Polar MM5 mesoscale model and in situ data. J. Geophys. Res. 109, D16105 (2004)

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Acknowledgements

This work was funded by the US National Science Foundation Office of Polar Programs, Arctic Natural Sciences with grants to J.H. (0612506), N.H. (0612374) and W.T.P. (0612351).

Author information

J.H. led the analysis, N.H. led the thermal measurements, W.T.P. led the ice-core measurements, J.B. led the radar measurements and X.F. downscaled MAR model output to the study transect. J.H., W.T.P., N.H. and J.B. contributed to the preparation of the manuscript.

Correspondence to J. Harper.

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The authors declare no competing financial interests.

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Harper, J., Humphrey, N., Pfeffer, W. et al. Greenland ice-sheet contribution to sea-level rise buffered by meltwater storage in firn. Nature 491, 240–243 (2012) doi:10.1038/nature11566

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