There may be a new cause for Greenland ice sheet melt. After studying two exceptional melt episodes in 2012, scientists have found a bit more about this ice sheet.
In this latest study, the researchers looked at the causes of ice sheet melt during the two melt episodes in 2012. These occurred from July 8 to 11 and from July 27 to 28. At that time, unusually warm and moist air impacted the ice sheet.
So how did they figure out what caused the melting other than the warm air? The researchers used PROMICE automatic weather station data and ranked the energy sources that contributed to surface melt during these time periods. More specifically, they looked at 12 sites around the ice sheet periphery.
So what did they find? Usually, ice melt is dominated by the radiant energy associated with sunlight. In this case, though, the researchers found that the energy associated with air temperature and moisture was the major driver of the exceptional melt episodes.
"Glaciological instrumentation capable of automatically recording the daily rate of melting in exceptional melt circumstances, where the ice surface lowers by close to 10 m in a few months, has only emerged in the last decade or so, thanks to PROMICE," said William Colgan of the Lassonde School of Engineering at York University. "The detail of PROMICE observations is permitting new insights on brief, but consequential, exceptional melt events."
The new findings have implications for how scientists project future ice sheet melt with the help of climate models. While the models used today can accurately simulate ice sheet melt due to radiant energy, they're ill-equipped to estimate the melt due to non-radiant energy processes. More specifically, the models underestimate these particular factors.
"Exceptional melt episodes dominated by non-radiant energy are expected to occur more frequently in the future due to climate change," said Robert Fausto of the Geological Survey of Denmark. "This makes it critical to better understand the influence of these episodes on ice sheet health."
The new findings help researchers take a step toward that goal. With that said, scientists still need to factor this into current models.
The findings are published in the March 2016 journal Geophysical Research Letters.
