So much about the planet’s future will depend on processes that humans today cannot directly observe — because they are occurring hundreds of meters below the sea surface where enormous marine glaciers, in Greenland and Antarctica, simultaneously touch the ocean and the seafloor.
The more we learn about this crucial yet inscrutable place, the more worrying it seems.
The latest exhibit: New research out of Greenland conducted by Dartmouth earth sciences Ph.D. student Kristin Schild and two university colleagues — work that has just been published in the Annals of Glaciology. The study examined the 5.5-kilometer-wide Rink Glacier of West Greenland, with particular focus on how meltwater on the ice sheet’s surface actually finds its way underneath Rink, pours out in the key undersea area described above and speeds up the glacier’s melt.
It’s a feedback process that, if it plays out across many other similarly situated glaciers, could greatly worsen Greenland’s overall ice loss. “These big tidewater outlet glaciers are the ones that are contributing these huge icebergs, they’re the ones that have rapidly, rapidly sped up in the last decade,” Schild said. This makes it critically important to learn “what are the main factors…that are leading to all these fast changes,” she added.
Greenland is an enormous sheet of ice, capable of raising sea levels by some 20 feet if it were somehow to melt entirely and its waters were to pour into the ocean. Fortunately, it can’t just do that all of a sudden — the vast ice sheet only reaches the ocean at relatively narrow, finger-like glaciers that stretch out into fjords, or underwater canyons that lead out to the sea.