From Greenland to the Graveyard
Each spring, an armada of ancient icebergs arrives off the coast of Newfoundland and Labrador. About 90% of these originate from the fast-moving glaciers of western Greenland. Formed by thousands of years of accumulating snow, the immense pressure eventually creates dense glacial ice. When these glaciers meet the sea, a process called calving releases massive pieces of ice, some weighing 100,000 to 200,000 tonnes—the size of a 15-story building.
These newly-born icebergs drift north and west around Baffin Bay before being caught in the southbound Labrador Current. This cold, fast-flowing current carries them down a path known as "Iceberg Alley," which stretches from the coast of Labrador to the southeast coast of Newfoundland. The entire trip from Greenland can take one to three years. Of the roughly 40,000 icebergs that calve from Greenland annually, only 400 to 800 typically survive the trip far enough south to reach the waters off St. John's. Their fate is sealed when the cold Labrador Current meets the warm, northward-moving Gulf Stream, which rapidly melts the ice. This confluence of currents also creates the dense fog that made these waters so hazardous for the RMS Titanic in 1912.
Ancient Atmospheres and Modern Monitors
The icebergs that reach Newfoundland are often over 10,000 years old, composed of freshwater snow that fell during the last ice age. Trapped within this dense ice are small air bubbles, which are pristine samples of Earth's ancient atmosphere. Scientists can analyze these bubbles to measure past concentrations of gases like carbon dioxide and methane, giving direct data on prehistoric climates. The ice itself is not salty and is so pure that local companies harvest it to make bottled water, vodka, and beer.
The sinking of the Titanic prompted the establishment of the International Ice Patrol (IIP) in 1914. Operated by the U.S. Coast Guard, its mission is to monitor the iceberg danger in the North Atlantic and warn ships. Early patrols involved cutters simply locating the southernmost iceberg and drifting alongside it until it melted. Today, the IIP uses a combination of aerial reconnaissance from HC-130J aircraft and satellite imagery to track the ice giants. Data from RADARSAT and other satellites helps differentiate icebergs from ships, though fog and sea conditions can still present challenges. This constant surveillance provides mariners with charts of the known iceberg limit, ensuring safe passage through these historic and icy waters.