Next generation projections of sea level contribution and freshwater export from the Greenland Ice Sheet

Loss of ice from glaciers and ice sheets is one of the most obvious consequences of global warming. As the planet warms we can expect increased rates of ice loss, and this ice ultimately ends up in the ocean causing sea level rise. Accurate projections of sea level rise are hugely valuable for societies around the world to make the best decisions on how to adapt to the increased risk of flooding in coastal areas. Ice loss also releases vast quantities of freshwater into the ocean, which has the potential to affect ocean currents, particularly in the North Atlantic where these currents are critical in regulating our climate. Accurate projections of freshwater flux into the North Atlantic from ice loss are therefore hugely important to assess whether the loss of ice will be sufficient to affect large-scale ocean currents, with implications for global climate.

The Greenland Ice Sheet is a vast mass of ice located in the North Atlantic, and is a key current and future source of global sea level rise and freshwater flux into the North Atlantic. Ice in Greenland is lost in two ways: (i) through melting of the ice sheet surface, forming liquid freshwater which flows into the ocean, and (ii) due to the flow of ice into the ocean through vast rivers of ice called tidewater glaciers; these glaciers produce huge icebergs which melt in the ocean. While reasonable confidence exists in our projections of ice sheet surface melting, projections of the flow of ice into the ocean are significantly less advanced.

Projections of the flow of ice into the ocean in Greenland have to date been held back by (i) a lack of understanding of how the flow responds to climate change (though it is thought that recent increases in ice flow are related to warmer ocean temperatures), and (ii) the high computational costs of running models of future ice flow into the ocean. The research proposed in this fellowship will offer novel solutions to these problems, increasing confidence in projections of sea level rise and freshwater flux from the Greenland Ice Sheet.

Specifically, I will develop a simple model for the transport of warm water from the ocean to the edge of the ice sheet, allowing us to quickly quantify the temperature of the ocean water which affects the ice sheet. I will also use datasets of ocean and air temperature and glacier behaviour from the past 100 years to develop simple relationships between glacier retreat and regional climate change. These two key developments will allow me to run computer simulations of the Greenland Ice Sheet which capture the flow of ice into the ocean, and its future evolution in a warming climate. With these computer simulations I will produce projections, with associated uncertainties, of future sea level rise and freshwater export into the North Atlantic from the Greenland Ice Sheet over the coming two centuries.

Who will benefit?

The academic beneficiaries have been detailed above. Beyond academia, this project will benefit (i) those undertaking international sea level assessments and setting international climate policy, (ii) more local policymakers, (iii) the general public, both adults and younger audiences and (iv) secondary school students and teachers.

How will they benefit?

International sea level assessments and policy
This project will have a direct impact on future IPCC sea level estimates by producing projections of sea level contribution from the Greenland Ice Sheet over the coming centuries. Through quantifying one of the major sources of sea level rise, this project will benefit policy makers around the world who are seeking to make the best decisions to adapt to changing sea level. In particular the focus in this fellowship on producing probability distributions for sea level contribution from Greenland will allow policy makers to quantitatively plan for both medium and worst-case scenarios. I have the research network and involvement in current relevant efforts to ensure my results are communicated to the relevant communities (LoS Straneo, Nowicki).

Similarly, the most recent IPCC assessment report states "There is low confidence in assessing the evolution of the Atlantic Meridional Overturning Circulation (AMOC) beyond the 21st century because of the limited number of analyses and equivocal results." This fellowship will deliver projections of future freshwater flux from Greenland - a key input to studies of the future of the AMOC - thus contributing to improved understanding and greater confidence in the conclusions of future IPCC assessment reports on which international policy is based.

Local policymakers
Constraining major sources of global mean sea level is a vital input to more focused assessments of sea level impacts, for example studies projecting local sea level rise (which can differ substantially from the global mean) and those assessing coastal flooding risk in specific communities.

The general public: adults and younger audiences
Climate change is a problem which needs to be tackled by everyone. As a community, therefore, we need to ensure that we raise awareness of both our own research and wider climate issues. Indeed, recent protests calling for action on climate change have shown that there is real public interest in up to date information about how our planet is changing. Through a program of outreach activities tailored to both adults and younger audiences, this fellowship will help to educate the general public on ice sheet instability under climate change.

Secondary school students and teachers
I will work with the Royal Scottish Geographical Society to develop a case study that relates my research to the Curriculum for Excellence and to develop continuing professional development training for secondary school teachers in Scotland. This will help facilitate coverage of ice sheets and climate change in schools, and contribute to ensuring teachers are up to date on the science.

The activities that will help to realise these impacts are detailed in the Pathways to Impact document.