The surface of the Earth is not completely rigid; in fact, it is more like a waterbed, with a semi-rigid crust floating on a viscous liquid known as the mantle. And like a waterbed, if the surface of the Earth is pushed down in one place, it will rise up in another. Ice-sheets and glaciers melting and the resulting flow of water into the oceans, has just this effect, meaning that future sea levels will not rise an equal amount around the world. This effect is known as Glacial Isostatic Adjustment (GIA).

Ice2sea’s efforts in trying to understand how European coastlines experience global sea-level rise require us to understand this “waterbed effect”. There are currently several complex models being developed to predict the effects on local sea-level of moving mass around the planet, but these use different mathematics and various assumptions, and they urgently need cross-validation. Ice2sea researchers are leading an effort in comparing these models by essentially setting tests to the various models and comparing the answers they produced. Their efforts have highlighted some notable disagreements, but the reasons for most of these have now been traced and corrected to produce a much more self-consistent set of models. The few remaining issues are the subject on ongoing work. This type of effort is a major step in moving away from prototype models, towards ones that can relied upon to produce accurate predictions of GIA on which important policy decisions can be based.

Ice2sea Work Package: WP6.2

Publication: Spada, G., V. R. Barletta, V. Klemann, R. E. M. Riva, Z. Martinec, P. Gasperini, B. Lund, D. Wolf, L. L. A. Vermeersen, and M. King (2010), A benchmark study for glacial-isostatic adjustment codes, Geophysical Journal International, 185(1), 106-132.