Upside-down rivers of warming ocean water are a threat to the stability of floating ice shelves in Antarctica, according to a new report from the University of Colorado’s National Snow and Ice Data Center.
Ice shelves are thick, floating plates of ice that have drifted away from the continent and spread out onto the ocean.
Karen Alley, a doctoral student who led the study, says knowing how shelves work will become more important as the planet gets warmer.
“They run into islands and peninsulas and pieces of the bedrock that help hold back the ice on the continent,” she explains. “And so if you lose an ice shelf, suddenly the ice behind it can flow much more quickly into the ocean. So they’re really important for regulating sea-level rise.”
The University of Colorado research found upside-down rivers, or basal channels, all around the Antarctic continent.
Alley says in many cases, the channels were making the ice shelves more vulnerable to collapse. She notes that while shelves take thousands of years to grow, they can disintegrate in a matter of weeks.
Both NASA and the National Oceanic and Atmospheric Administration have confirmed that February 2016 was the planet’s warmest February since record keeping began in 1880.
Alley notes that ice shelves are especially vulnerable because climate change hits them from the air above and water below. She says although more research is needed to find all factors that can destabilize shelves, the basal channels are a key discovery.
“This is one potential factor,” she states. “If we’re going to predict how sea level rise will work in the future, how fast things will change, we have to understand ice shelves.”
When a channel is carved into the underside of an ice shelf, the top sags, leaving a visible wrinkle on the smooth surface. Alley’s team used satellite photos to map wrinkles across the continent, and radar imaging to locate the rivers flowing beneath the ice.