Meltwater Ice-sheet Interactions and the changing climate of Greenland (MII-Greenland)

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.

This project will provide a new state-of-the-art estimate of the future contribution of the Greenland ice sheet to global sea level, and the first estimate of future proglacial water flux to the ocean. Since the former is an important climate impact and the latter may contribute to a potential climate feedback our estimates will have major implications for lives and livelihoods worldwide. We have identified four main stakeholders with an interest in this particular work: 1) policy makers, who require accurate information in order to make informed policy decisions, 2) the science leaders of the future (young people) 3) the general public who can use this information to make informed lifestyle choices and 4) the transport and infrastructure industry who use future climate projections to guide building and maintenance plansSpecific examples of how the MII-Greenland project will be useful to these stakeholders are:

1) Policy makers: Policy makers worldwide are interested in accurate assessments of climate and sea-level change in order to make informed decisions which allow populations to reduce, adapt to and mitigate any adverse effects. Policy makers typically rely on documents such as the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports for their information and so in order to ensure that our work features in these documents, we will exploit our existing relationships with leading IPCC authors including Prof Piers Forster (U Leeds) and Prof Anthony Payne (U Bristol). We will keep Profs Forster and Payne informed as to the progress of the project and take advantage of any opportunities that arise to contribute directly to future IPCC reports during the project.

2) Science leaders of the future: understanding the science behind ice sheet change, and it's global impact, is challenging. In order to facilitate wider understanding in this area, we will deliver a public engagement campaign around the 'Ice Flows' educational computer game (www.iceflowsgame.com). Central to the value of Ice Flows in delivering impact is promotion and dissemination. We will develop teaching resources in partnership with The Geographical Association and deliver engagement campaign to bring the game and resources into schools with the support of the UK Polar Network (see letter of support).

3) General Public: The fate of the ice sheets is an issue that the general public can identify with, and indeed this information is important to enable them to make informed lifestyle choices (e.g. buying a house close to the coast or on a floodplain). We will we will maintain a public facing webpage hosted on the Lancaster University site which will be linked into social media (e.g. Lancaster Environment Centre has ~2000 twitter followers). With support from the Press Offices of partner Universities, press releases detailing significant findings and activities will be developed and articles relating to the project will be published across local and national media spanning websites and print.

4) Transport and Infrastructure sector: In order to develop adequate - but cost effective - strategies for the adaptation and mitigation of coastal roads and railways to rising sea levels, infrastructure and transport providers require the best possible predictions of future sea level change. In that respect, we have engaged with Kaine Lynch in the Roads division at Transport Northern Ireland who is interested in potential increases in landslide events associated with sea level rise. We will keep Mr Lynch informed as to the progress of the project and explore opportunities for joint projects around sea level rise and roads as they arise during the work.