This blog is written by Rob Storrar, a glaciologist working at Sheffield Hallam University. He uses drones to make 3D models of glaciers to understand how they behave in a changing climate. Follow Rob on Twitter @rob_storrar.
The polar regions have always been mysterious, and their secrets have been hard to unlock. In the early days of polar exploration this involved gruelling and perilous journeys. Advances in technology, especially satellites, means that our understanding of the polar regions has exploded in the last few decades. However, mysteries still persist; especially when it comes to understanding what is underneath the ice. This remains a very difficult environment to study, but is becoming more and more important, as climate change drives rapid ice melt.
The fate of Greenland’s melting ice and hidden lakes
The Greenland Ice Sheet is a single mass of ice that is up to 3 kilometres thick, ~700 kilometres wide, and ~2,300 km long. It contains enough ice that, were it to melt entirely (which is not likely to happen any time soon), it would raise global sea levels by about 7 metres. We do not expect all of Greenland’s ice to disappear completely, but melting of Greenland ice is currently the single largest contributor to sea level rise and this is set to increase.
Greenland loses ice directly into the sea, where icebergs break off from what are known as ‘tidewater’ glaciers. It also loses ice by melting on the surface. This surface melting produces large volumes of liquid water, which can then affect how quickly the remaining ice flows as it makes its way to the sea. Water can enter the ice through cracks and make its way right to the bottom of the ice sheet, where it can either drain away in large channels, or can pool and act to speed up the flow of ice.
It has only recently been discovered that underneath Greenland’s huge ice sheet are hidden lakes. Some of these are connected to the channels that water from the surface travels through, whilst others sit alone. Sometimes these lakes suddenly empty, releasing vast amounts of water into channels and cracks underneath the ice sheet.
The amount of melting that Greenland experiences is increasing rapidly, so understanding the fate of meltwater and the ways it affects the ice is extremely important. Understanding how and why these hidden lakes drain, and what this might mean for the future, is the aim of the SLIDE project, which I am very fortunate to be a part of.
The SLIDE project field camp in south west Greenland (photo: R. Storrar).
The SLIDE project – exploring under the ice
The SLIDE project is a large 3 year project led by Prof Stephen Livingstone at the University of Sheffield, funded by the UK’s Natural Environment Research Council, that brings together over 20 researchers to investigate why lakes exist underneath the ice in Greenland, what happens when they drain, and how they may change in the future. The work involves monitoring and studying these lakes using a range of scientific tools that allow us to explore the world underneath the ice.
The SLIDE project team has installed 14 GPS (Global Positioning System) units onto a glacier named Isunguata Sermia. These sit on 6 metre long poles drilled into the ice (so they don’t fall over when it melts). The GPS monitor how fast the ice moves, and whether it goes up or down. We also use remote-controlled drones to make 3D models of the glacier, and can use these to measure locations which are moving faster or slower, and to see where the ice goes up or down. When a lake drains, we expect to see the ice go down where the lake was, and up where the water drains (the water pressure can actually lift the ice!)
We use radar to ‘look’ underneath the ice, and we can use this to see the surface of the lakes, measure how thick the ice is, and study the shape of the land underneath the ice. This helps us understand why there are lakes. We use seismic equipment to ‘listen’ to the glacier as it creaks and groans, which can tell us how much water is passing through, and how this is affecting the glacier movement. We also use special probes called ‘Cryoeggs’ which we can put into holes in the ice; they send readings of temperature, pressure, and other things back to the surface, so we can explore the conditions beneath hundreds of metres of ice.
Drilling a hole in the ice to install a seismic probe (photo: R. Storrar).
These different tools, and more, will help us understand why there are lakes, and how the plumbing system of the glacier works. We will use this knowledge to help predict the effect the lakes have on the glacier, both now and, importantly, into the future as more melting happens, and more water is added. Our hope is that we can better understand and predict how the Greenland Ice Sheet will respond to climate change, and especially to future sea level rise.
The study of ice sheets and glaciers through time is a vital part of geoscience, both in helping us understand and prepare for the impacts climate change is having upon our world, and in contributing scientific evidence to the case for governments to take positive action on climate change.