Investigating the climate feedbacks that will determine the fate of the Greenland ice sheet

Sea level change is one of the most widely recognised and zoompotentially serious consequences of climate change due to emissions of greenhouse gases. The contribution to sea level change from melting the polar ice sheets on Greenland and Antarctica has already raised global sea levels by around 20mm since 1993, and this rate is expected to grow over the 21st century. Ice mass loss is the most uncertain part of the sea level change budget, largely because the science of modelling how large ice sheets interact with a changing climate has been severely limited by the fact that climate and ice sheet models do not work well together.

This project proposes to use our new and unique modelling capabilities to gain new understanding of the ways in which the atmosphere and ice sheets interact. Focusing on the Greenland ice sheet, this project will investigate the atmospheric, ocean and land surface physics that determine the sensitivity of changing large-scale surface conditions on the ice, and how changes in ice extent and height feedback on both local and regional climate and atmospheric circulation.

Studies with regional and global climate models for the coming century have shown that predictions of how much of the surface of the ice will melt ice for a given level of climate change can vary by factor of two or more. And whilst it has been appreciated for some time that warming of the surface due to its reduction in altitude as it melts is a crucial part of predicting the centennial rate of mass loss from Greenland, it now seems likely that changes in snowfall due to the changing shape of the ice sheet may be just as important. There are several interacting atmospheric, snow surface and ice flow processes involved in these large-scale feedbacks, and yet little research into the phenomena. How much, and in what way, ocean temperatures govern the calving rates of outflow glacier is also an important unknown.

This project will use a state-of-the-art model, used to make the UK's global climate projections, interactively coupled to a dynamical model of the Greenland ice sheet. A series of experiments will investigate the mechanisms of climate-ice interactions, their links to the regional climate system and what they imply for the long-term future of the Greenland ice sheet. In parallel, observational data (obtained via remote sensing and in situ) will be used to both verify the model's capabilities and improve its physical parameterisations.