Joughin, I. and Bamber, J.L. 2005. Thickening of the ice stream catchments feeding the Filchner-Ronne Ice Shelf, Antarctica. Geophysical Research Letters 32: L17503, doi:10.1029/2005FL023844.
What was done
Among the many model-based predictions of the deleterious consequences of CO2-induced global warming is the melting of significant portions of earth's polar ice caps, which could raise the level of the world's oceans and inundate low-lying coastal locations with seawater. As a result of this concern, many researchers have attempted to evaluate trends in the mass balances of the polar ice sheets, with some of them producing results that are at odds with each other. Rignot and Thomas (2002), for example, utilized a "flux gate" method that yielded a recent thinning of the catchments feeding several ice streams in East Antarctia. Davis et al. (2005), on the other hand, employed satellite altimetry data and reported a significant thickening of the same region. Consequently, Joughin and Bamber set out to resolve the discrepancy by re-evaluating the mass balances of the ice stream catchments feeding the Filchner-Ronne Ice Shelf. They too used the flux-gate method, but with improved data and area of coverage.
What was learned
The new and improved data made all the difference in the world to the mass balance calculations of the Filchner-Ronne Ice Shelf and closed the gap between the previous estimates of Rignot and Thomas (2002) and Davis et al. (2005). Instead of the 3.6 ± 9.1 Gton/yr net thinning estimate of Rignot and Thomas, Joughin and Bamber found a net thickening of 39 ± 26 Gton/yr (= 1.6 ± 1 cm/yr), which is nearly identical to the 1992-2003 estimate of Davis et al. and is equivalent to a sea-level reduction of 0.11 ± 0.07 mm/yr. Furthermore, Joughin and Bamber state that their mass balance estimates are likely representative of trends that have been occurring over "at least" the last several decades, and that they may yet be significantly influenced by a continuing response to the approximately 50% accumulation increase that began in the early Holocene.
What it means
It is clear from the results of this study that the Filchner-Ronne Ice Shelf is not rapidly, or even slowly, wasting away. Quite to the contrary, it is growing.
Davis, C.H., Li, Y., McConnell, J.R., Frey, M.M. and Hanna, E. 2005. Snowfall-driven growth in East Antarctic Ice Sheet mitigates recent sea-level rise. Sciencexpress/www.sciencexpress.org/science.1110662.
Rignot, E. and Thomas, R.H. 2002. Mass balance of polar ice sheets. Science 297: 1502-1506.Reviewed 7 December 2005