Glacial isostatic adjustment observations and modeling: A closer look at Greenland

nov 26
Wanneer 26 november 2020, aanvang 16:00
Waar Webex

Speaker: Ir. Maaike F. M. Weerdesteijn, Doctoral Research Fellow, Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway

As the climate warms in the past decade, the melting of the Greenland and Antarctic Ice Sheets have been accelerating. As the ice melts, the rocks beneath the ice become unloaded and rebound elastically, causing surface uplift. In addition, the ground surface of Greenland and Antarctica is also deforming slowly in response to melting that occurred during the last deglaciation. This process is called postglacial rebound, and it is one of the components in glacial isostatic adjustment (GIA). The modern field of GIA concerns the geodynamical problem of determining the solid Earth response to surface load changes by ice and ocean water, whilst at the same time solving for the gravitationally consistent redistribution of seawater across the global ocean.

The two causes of solid Earth deformation and seawater distribution, due to past and present ice melt, are mingled in geodetic observations. Therefore, one needs to model the GIA component in order to find accurate estimates of present-day ice melt and sea level change. The GIA component is difficult to predict because it is sensitive to mantle viscosity, which is largely unconstrained beneath the current ice sheets, and it is sensitive to the ice history. Here, we will take a closer look at Greenland. GIA patterns may be especially complex because Greenland mantle viscosity is likely to vary laterally. Much of the Greenland mantle is old and cold and therefore likely to be stiff, while the portion beneath central Greenland may have been impacted by the Iceland plume which may make it hotter and weaker.

This talk will take you through the principles behind GIA, observations and modeling, and its impact on climate change estimates.

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