The Greenland ice sheet (GrIS) is shrinking as Earth’s climate warms. In fact, meltwater which runs off the ice sheet is expected to contribute ~10 cm to global sea level by 2100 (Fettweis et al., 2013). This would double the number of people currently experiencing flooding (Nicholls, 2006) potentially cuasing the loss of lives and livelihoods worldwide.
Additionally, because meltwater is fresh as opposed to salty, and can contain dissolved nutrients, high meltwater fluxes to the ocean can potentially have an impact on ocean circulation (Luo et al., 2016) and coastal/fjord ecosystems (e.g. Hawkings et al., 2015). In addition to these direct impacts, on its journey out to sea, the meltwater runoff is implicated in a range of processes which also contribute to ice loss (known as feedbacks). Importantly, this includes surface meltwater which is routed underneath the ice sheet, where it can lubricate ice flow (Schoof 2010). This suggests that increases in melt due to a warming climate could lead to a sustained speed-up of the ice sheet; leading to a thinning and flattening. This would exacerbate melting by bringing more ice to elevations with warmer air temperatures, potentially resulting in more mass loss. It is not yet clear whether this will occur because of the complicated processes involved (e.g. Tedstone et al., 2015), however our research has that shown more of the sub-ice sheet environment is likely to be exposed to these processes in the future (Leeson et al., 2015). As such, improving our understanding of the system and how it functions is of great importance. At present, future GrIS change (e.g. estimates of sea level contribution which feature in the Intergovernmental Panel on Climate Change – IPCC – assessment reports) is predicted using ice sheet models which do not fully account for the feedback processes outlined above. The impact of surface melting on ice flow is controlled by surface and basal hydrological features, for example lakes and streams. These features are too small, and evolve too quickly, for the ice sheet models to simulate, which is why they have not been included in these models until now. Recent technological advances pioneered by our project team (e.g. Goldberg et al., 2009 and Gourmelen et al., 2017) however, now allow for ice sheet models to simulate both small and large scale processes and state-of-the art satellites now capture enough information for us to fully evaluate such a model. In this project we will exploit these advances and develop a new, robust, coupled hydrology/ice-sheet model which is thoroughly constrained and tested against new, and dedicated, observations. We will then use the model to 1) improve our understanding of the role of surface meltwater in ice dynamics and 2) simulate the GrIS response to changes in surface melting expected under IPCC climate warming scenarios.