In January 2010 I’m starting a PhD with the Bristol Glaciology Centre at the University of Bristol.

The title is: Constraining the mass balance of the Greenland Ice Sheet

Sea level rise is considered to be one of the most significant and dangerous consequence of global warming. Clearly, a major potential contribution to sea level rise are the ice sheets of Antarctica and Greenland, with the latter predicted to be particularly vulnerable to climate change over the next century [Gregory et al., 2004; Gregory and Huybrechts, 2006]. Complete removal of the ice sheet would result in a mean global sea level rise of around 6 m [Bamber et al., 2007]. Recent observations suggest that the mass loss from Greenland has increased dramatically over the last ~decade, possibly as a consequence of regional increases in ocean and atmospheric temperature [Rignot and Kanagaratnam, 2006].

Satellite remote sensing data offer our best chance of quantifying and monitoring the mass trends of the Greenland Ice Sheet (GrIS) but, unfortunately, the various approaches available suffer from errors and issues that render no one approach adequate [Cazenave, 2006; Thomas et al., 2006] (see Fig 1). The three main satellite methods comprise measuring elevation changes through time (dh/dt) [Zwally et al., 2005], changes in the gravity field from the GRACE satellites [Luthcke et al., 2006], and mass budget calculations using satellite observations of velocity with estimates of the surface mass balance [Rignot and Kanagaratnam, 2006].

Figure 1. Various satellite estimates of the mass balance of the Greenland ice sheet (Cazenave, 2006). The thickness of the boxes indicates the error for the estimate. Note that, in some cases, the boxes do not overlap, which means that they do not agree within their combined errors, even though several of the estimates use a similar approach.

The aim of my project is to combine all three approaches to allow us to solve for the different errors that afflict each method and, as a consequence, solve for the mass balance and post glacial rebound signals. Measuring the latter can provide valuable information about ice volume changes on longer timescales [Tamisiea et al., 2007].

References:

Bamber, J. L., et al. (2007), Rapid response of modern day ice sheets to external forcing, Earth Plan. Sci. Lett., 257, 1-13.
Cazenave, A. (2006), How fast are the ice sheets melting?, Science, 314(5803), 1250-1252.
Gregory, J. M., et al. (2004), Threatened loss of the Greenland ice-sheet, Nature, 428(6983), 616-616.
Gregory, J. M., and P. Huybrechts (2006), Ice-sheet contributions to future sea-level change, Phil Trans Roy Soc, A, 364(1844), 1709-1731.
Luthcke, S. B., et al. (2006), Recent Greenland ice mass loss by drainage system from satellite gravity observations, Science, 314(5803), 1286-1289.
Rignot, E., and P. Kanagaratnam (2006), Changes in the Velocity Structure of the Greenland Ice Sheet, Science, 311(5763), 986-990.
Tamisiea, M. E., et al. (2007), GRACE gravity data constrain ancient ice geometries and continental dynamics over Laurentia, Science, 316(5826), 881-883.
Thomas, R., et al. (2006), Progressive increase in ice loss from Greenland, Geophysical Research Letters, 33(10), L10503.
Zwally, H. J., et al. (2005), Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992–2002, J. Glaciol., 51(175), 509-527.