The team of researchers, led by CPOM PhD Researcher Jade Bowling and CPOM Co-Director for Science Professor Malcolm McMillan (Lancaster Environment Centre), studied the sudden draining of a recently detected lake under the Greenland ice sheet (subglacial lake), using European Space Agency (ESA) and NASA satellite data and 3D simulations from the ArcticDEM project.
Their studies revealed that 90 million cubic meters of water burst through the ice leaving a huge crater (85m deep) across a 2 km2 area of the ice sheet. Further downstream they found hundreds of thousands of square metres of fractured ice and 25m high ice blocks where the flood had drained.
This evidence of meltwater flowing upwards from base to surface has overturned previous assumptions that meltwater only flows in the opposite direction. This, combined with previous ice sheet model predictions that the ice bed in this region was frozen has led the team to propose that fracturing of the ice created the pressure to forge a path for the water to flow through.
These new mechanisms have not been incorporated into the models that we use to project future behaviour of ice sheets in a warming climate, further emphasising that better understanding of the complex hydrological processes beneath the ice surface is vital if we are to prepare for continued, increased melting of the ice sheets in the coming decades.
Information we derive from satellite missions, and the computer simulations of what is and might happen within and below the ice sheets, are hugely important in planning for sea level rise and other environmental and weather changes associated with an evolving climate, to protect people, infrastructure and habitats.
Lead author Dr Jade Bowling, who led this work as part of her PhD at Lancaster University, said:
“When we first saw this, because it was so unexpected, we thought there was an issue with our data. However, as we went deeper into our analysis, it became clear that what we were observing was the aftermath of a huge flood of water escaping from underneath the ice.
“The existence of subglacial lakes beneath the Greenland Ice Sheet is still a relatively recent discovery, and – as our study shows – there is still much we don’t know about how they evolve and how they can impact on the ice sheet system.
“Importantly, our work demonstrates the need to better understand how often they drain, and, critically, what the consequences are for the surrounding ice sheet.”
Professor Mal McMillan, Co-Director of the Centre of Excellence in Environmental Data Science at Lancaster University, and Co-Director of Science at the UK Centre for Polar Observation and Modelling, said:
“This research demonstrates the unique value of long-term satellite measurements of Earth’s polar ice sheets, which – due to their vast size – would otherwise be impossible to monitor.
“Satellites represent an essential tool for monitoring the impacts of climate change, and provide critical information to build realistic models of how our planet may change in the future. “This is something that all of us depend upon for building societal resilience and mitigating the impacts of climate change.”
Dr Amber Leeson, Reader in Glaciology at Lancaster University and an expert in ice sheet hydrology said:
“What we have found in this study surprised us in many ways. It has taught us new and unexpected things about the way that ice sheets can respond to extreme inputs of surface meltwater, and emphasised the need to better understand the ice sheet’s complex hydrological system, both now and in the future.
This research, led by Jade Bowling and Malcolm McMillan (Lancaster University) is a collaboration between:
