The Sensitivity of Sea-Level Fingerprints to the Geometry of Ice Sheet Mass Balance

Sea-level changes in response to the rapid melting of individual ice sheets or mountain glaciers are characterized by distinct geometries that have come to be known as fingerprints. We examine the sensitivity of these fingerprints to a variety of model inputs, including the detailed geometry of the ice sheet mass balance. For example, we compare fingerprints associated with early tabulations of mountain glacier flux to more recent estimates of the mass balance within these ice reservoirs. This comparison highlights the potential for a strong time dependence in the fingerprints. Moreover, we compare fingerprints computed under the common assumption of uniform melt geometries in Greenland and Antarctica to those predicted using more realistic geometries inferred from in situ and geodetic measurements, including data collected from the GRACE satellite gravity mission. Finally, we describe projections spanning the next several centuries, when warming is expected to lead to substantial changes in the extent of the polar ice sheets; including, for example, the potential collapse of marine-based sectors of the Antarctic ice sheet. These projections highlight the full suite of physical effects that contribute to the fingerprints and the computational care that must be taken to obtain accurate results.