By now, many of us are aware of the 5th Intergovernmental Panel on Climate Change (IPCC) report, which has attracted a storm of media attention since its publication last month. The report considers the environmental consequences of many possible climatic scenarios. These consequences include global warming-induced sea level rises, a product of the thermal expansion of sea water and melting land-ice running into the seas. However, there is much discourse over the extent and rate of future rises, partly due to insufficient knowledge of the mechanisms underlying melting land-ice. Recent research from Stanford University provides insight into a possible complexity with land-ice melting: the phenomenon of liquid water trapped within glaciers. This mechanism has not been previously studied, and should be considered in future models to help us more accurately predict how melting land-ice will impact our planet.
The researchers from Stanford used ice-penetrating radar to identify density variations within the Store Glacier in West Greenland. Regions of higher density indicated trapped water, and higher density regions correlated with glacial areas that had recently been melting. From this correlation, the researchers inferred that meltwater had trickled into, and become trapped within fractures in the ice. Meltwater is known to impact glacial movement by flowing to the base where it contributes to basal lubrication and a subsequent increase in glacial sliding. The siphoning-off of meltwater into pockets within the ice may modify this process, by either delaying or entirely preventing the meltwater from reaching the base. How the ice melts and where the meltwater flows will contribute to how a glacier responds to future climatic conditions, which will impact the predicted timeline for future sea level rises.
Previous research has focused on surface changes to glacial landscapes, whilst the Stanford study offers insight into more diverse glacial melt mechanisms. With around 40% of the global human population living within 100km of coasts, the need for accurate sea level predictions has never been greater. The Stanford study demonstrates that a more in-depth approach to studying and modelling land-ice melting will be required for climate scientists to make better predictions of future sea level rises, and help us prepare for what the future brings.