Accelerating uplift in the North Atlantic region as an indicator of ice loss

Vertical motions of the rocky margins of Greenland and Antarctica respond to mass changes of their respective ice sheets(1,2). However, these motions can be obscured by episodes of glacial advance or retreat that occurred hundreds to thousands of years ago(3-6), which trigger a delayed response because of viscous flow in the underlying mantle. Here we present high-precision global positioning system (GPS) data that describe the vertical motion of the rocky margins of Greenland, Iceland and Svalbard. We focus on vertical accelerations rather than velocities to avoid the confounding effects of past events. Our data show an acceleration of uplift over the past decade that represents an essentially instantaneous, elastic response to the recent accelerated melting of ice throughout the North Atlantic region. Our comparison of the GPS data to models for glacial isostatic adjustment suggests that some parts of western coastal Greenland were experiencing accelerated melting of coastal ice by the late 1990s. Using a simple elastic model, we estimate that western Greenland's ice loss is accelerating at an average rate of 8.7 +/- 3.5 Gt yr(-2), whereas the rate for southeastern Greenland-based on limited data-falls at 12.5 +/- 5.5 Gt yr(-2).