Climate-driven methane outgassing at terrestrial and marine-terminating glacier margins

Methane emissions from retreating Arctic glaciers have the potential to increase significantly over the rest of the 21st Century. These emissions will make management of greenhouse gas levels difficult during a critical period for climate change mitigation. Our project will provide important information about how much more methane will escape as glaciers on land retreat further and as glaciers in the sea retreat onto land. We will therefore measure gas release from the new land surface exposed by recent glacier retreat, as well as from the sea surface, right in front of marine-terminating glaciers. On land, we will investigate how meltwater pressurises groundwater beneath the glacier, which then forces the gas towards the glacier margin. We will then apply this knowledge to the marine glaciers, where observations of groundwater that carry the gas towards the fjord are more difficult to collect. To make this easier, we will also use boats and sea ice as platforms to locate gas bubbles leaking from the seabed. Monitoring both types of glacier margin will allow us to develop an understanding of the relationship between climate change and the rate of gas release. Numerical models can then be used to predict whether the rate will increase as the glaciers rapidly shrink, or even decrease, as the effects of the glaciers upon their surrounding environment begins to diminish. Knowledge derived from Svalbard will then be applied to other parts of the Arctic where similar geology, permafrost and glacier conditions also exist. Since most of the methane we are studying is ancient and derived from sedimentary rocks, our work will be particularly relevant to the Russian Arctic islands, the Baffin Bay area, East and West Greenland, and other parts of the Canadian Arctic.

Managing emissions of methane is a major societal challenge for the rest of the 21st Century because it is such a potent greenhouse gas. This requires accurate estimates of natural methane emissions, especially from the Arctic. Here it is known that one of the greatest sources of uncertainty is the release of gas trapped beneath frozen ground (permafrost) and glacier ice. We have found that a significant amount of this gas is already escaping to the atmosphere in Svalbard (> 2000 tons a year, perhaps equivalent to as much as 10% of emissions associated with Norway's energy sector). However, we also know that the rate of gas escape will increase markedly as climate change continues. This is because there is a vast gas resource sitting in the rocks beneath Svalbard, and the glaciers are melting so rapidly that it able to escape as soon as the glaciers retreat. Our project therefore proposes to use novel observation platforms and numerical models to understand and quantify how increasing glacier melt results in greater gas emission to the atmosphere at glacier margins. We will be the first to examine glaciers that terminate in the sea, including those glaciers also about to retreat onto land. Lastly, we will use our expertise from Svalbard to locate similar emission hotspots in Canada, Greenland and Russia. The project must address technical challenges associated with getting close to marine glaciers and with monitoring all year in the harsh Arctic climate. We will make full use of the experience gained by the lead institution's all-year presence in Svalbard. We have already used this to develop appropriate observation tools that can operate under such conditions. Since the fjords can be particularly hazardous, we will also use the stable winter sea ice as a platform for observations before the dynamic summer period starts. Then remotely operated vehicles and small boat operations will allow us to work opportunistically, when the conditions are safe and suitable.