In 2011, scientists explained that the Greenland Ice Sheet “could undergo a self-amplifying cycle of melting and warming” that is “difficult to halt.”
Last November, a major international study in the journal Science found that the Greenland ice sheet’s melt rate was up nearly 5-fold since the mid-1990s.
This acceleration has put ice sheet loss far ahead of what most climate models had predicted several years ago. Now a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) in the Journal of Geophysical Research: Earth Surface explains at least one key factor the models have missed:
Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster.
The study notes that not only has the Greenland ice sheet accelerated at the edges where they flow into the ocean, but the “interior regions are also flowing much faster than they were in the winter of 2000-2001.”
To shed light on the observed acceleration, [Lead author Thomas] Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that meltwater warms the ice sheet, which then—like a warm stick of butter—softens, deforms, and flows faster.
Previous studies estimated that it would take centuries to millennia for new climates to increase the temperature deep within ice sheets. But when the influence of meltwater is considered, warming can occur within decades and, thus, produce rapid accelerations.
Coauthor William Colgan explained, “The model shows that a slight warming of the ice near the ice sheet bed—only a couple of degrees Celsius—is sufficient to explain the widespread acceleration.”
The findings have important ramifications for ice sheets and glaciers everywhere. “It could imply that ice sheets can discharge ice into the ocean far more rapidly than currently estimated,” Phillips said. “It also means that the glaciers are not finished accelerating and may continue to accelerate for a while. As the area experiencing melt expands inland, the acceleration may be observed farther inland.”
This new study only serves to underscore a 2012 study that found we may be close to the Greenland Ice Sheet’s “tipping point.” The time to act is now!